Re: [AFMUG] -48V kicking the dead horse
That is what I've always done and got told I'm wrong LOL On 1/9/24 7:17 AM, Brough Turner - netBlazr wrote: "Ring, Ridge, Red, Right" was the equivalence in the days when Telephone Operator Cord Boards had tip/ring/sleeve connectors on the cords. So Ridge = Red. Thanks Brough *From:* AF on behalf of Robert *Sent:* Monday, January 8, 2024 10:32 PM *To:* af@af.afmug.com *Subject:* Re: [AFMUG] -48V kicking the dead horse But what about Low voltage cable... Is smooth hot or cold or ridged hot or cold? So many choices... LOL.. On 1/8/24 9:39 AM, dmmoff...@gmail.com wrote: > I concur with the wire color problem. > > * My current employer pays big bucks to a low voltage guy who wires up our > sites. His work is absolutely beautiful. It's like friggin artwork. > He uses black for return (+) and green for ground. Then since most of our > equipment has dual power supplies he uses red and blue for the "A" hot and > "B" hot. I assume his employer trained him that way for a reason and that's > probably common. > > * I was taught in childhood that red is positive, so that's what I have > always done. I'm not philosophically opposed to the idea that red is "hot", > but that's just now how I learned it. > > * https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fztlabels.com%2Fblogs%2Fnews%2Fdc-power-circuit-wiring-color-codes&data=05%7C02%7Cbrough%40netblazr.com%7C6c42b49a25dd404e07d908dc1099eb1a%7C06a97f73bf7b45a688f6a3a7bc5f56c7%7C0%7C0%7C638403500474986051%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=NwfihmgJY1P%2FJX8FZ9QQK%2Fbx95TQIV3AqoM5Wowvai0%3D&reserved=0 <https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes> > This site advises that for 2-wire DC with positive ground is white for > positive and black for negative. Someone apparently thinks that's the right > way. The same site points out that the only color called out specifically > in the NEC is green or green/yellow for ground. Everything else is just the > convention people landed on. > > Out in the wild you might see anything so there is and will always be a > multi-meter in my everyday toolkit. > > -Adam > > > > -----Original Message- > From: AF On Behalf Of Ken Hohhof > Sent: Monday, January 08, 2024 12:01 PM > To: 'AnimalFarm Microwave Users Group' > Subject: Re: [AFMUG] -48V kicking the dead horse > > What I can never decide on is wire colors. Especially when using red/black > zipcord or tray cable. People expect red to be +, but they also expect > black to be ground (except electricians who expect black to be hot and white > to be neutral and green or green/yellow to be ground). And how to > differentiate battery wiring from load wiring. I have not found an ideal > solution other than labels. > > -Original Message- > From: AF On Behalf Of Bill Prince > Sent: Monday, January 8, 2024 10:45 AM > To: af@af.afmug.com > Subject: Re: [AFMUG] -48V kicking the dead horse > > Yes. -48VDC means the negative side is hot, and the positive side is ground > (or return). > > You can mix +48VDC and -48VDC if you know what you're doing. It helps a > bunch if the equipment floats logic ground. You need to check to see if your > equipment isolates logic from the supply voltage. > > Yes. Batteries can be grounded either way. They don't care. > > bp > > > On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: >> I know we have been though this many times and I thought I understood it. >> >> -48VDC is the Negative side being HOT, correct? >> >> It is BAD to try to mix -48VDC and 48VDC >> >> There is no such thing as a -48V battery. A battery is a battery, > correct? >> How about the ICT Platinum power supplies. They show as 48VDC, can >> they > be used on -48VDC equipment? >> I remember Check saying something about a way to test to see if a >> piece of > equipment that is Neg 48VDC is truly grounded as Neg 48VDC. >> >> -- >> >> Thanks, >> Mark mailto:m...@mailmt.com <mailto:m...@mailmt.com> >> >> Myakka Communications >> https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.myakka.com%2F&data=05%7C02%7Cbrough%40netblazr.com%7C6c42b49a25dd404e07d908dc1099eb1a%7C06a97f73bf7b45a688f6a3a7bc5f56c7%7C0%7C0%7C638403500474986051%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=FlUnCHHmZ9Qohes%2BwvKB9GMSitPQuiBOFVDDBFJOdNw%3D&reserved=0
Re: [AFMUG] -48V kicking the dead horse
The ridge was on the aerial drop wire. It went to the right hand binding post on the protector. The red wire of the station wire also went on the right and they were the “Ring” side of the line or hot side with –48 volts. You could actually make a call by connecting to the ring and ground but it would be very noisy. From: Brough Turner - netBlazr Sent: Tuesday, January 9, 2024 8:17 AM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse "Ring, Ridge, Red, Right" was the equivalence in the days when Telephone Operator Cord Boards had tip/ring/sleeve connectors on the cords. So Ridge = Red. Thanks Brough From: AF on behalf of Robert Sent: Monday, January 8, 2024 10:32 PM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse But what about Low voltage cable... Is smooth hot or cold or ridged hot or cold? So many choices... LOL.. On 1/8/24 9:39 AM, dmmoff...@gmail.com wrote: > I concur with the wire color problem. > > * My current employer pays big bucks to a low voltage guy who wires up our > sites. His work is absolutely beautiful. It's like friggin artwork. > He uses black for return (+) and green for ground. Then since most of our > equipment has dual power supplies he uses red and blue for the "A" hot and > "B" hot. I assume his employer trained him that way for a reason and that's > probably common. > > * I was taught in childhood that red is positive, so that's what I have > always done. I'm not philosophically opposed to the idea that red is "hot", > but that's just now how I learned it. > > * > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fztlabels.com%2Fblogs%2Fnews%2Fdc-power-circuit-wiring-color-codes&data=05%7C02%7Cbrough%40netblazr.com%7C6c42b49a25dd404e07d908dc1099eb1a%7C06a97f73bf7b45a688f6a3a7bc5f56c7%7C0%7C0%7C638403500474986051%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=NwfihmgJY1P%2FJX8FZ9QQK%2Fbx95TQIV3AqoM5Wowvai0%3D&reserved=0 > This site advises that for 2-wire DC with positive ground is white for > positive and black for negative. Someone apparently thinks that's the right > way. The same site points out that the only color called out specifically > in the NEC is green or green/yellow for ground. Everything else is just the > convention people landed on. > > Out in the wild you might see anything so there is and will always be a > multi-meter in my everyday toolkit. > > -Adam > > > > -----Original Message----- > From: AF On Behalf Of Ken Hohhof > Sent: Monday, January 08, 2024 12:01 PM > To: 'AnimalFarm Microwave Users Group' > Subject: Re: [AFMUG] -48V kicking the dead horse > > What I can never decide on is wire colors. Especially when using red/black > zipcord or tray cable. People expect red to be +, but they also expect > black to be ground (except electricians who expect black to be hot and white > to be neutral and green or green/yellow to be ground). And how to > differentiate battery wiring from load wiring. I have not found an ideal > solution other than labels. > > -Original Message- > From: AF On Behalf Of Bill Prince > Sent: Monday, January 8, 2024 10:45 AM > To: af@af.afmug.com > Subject: Re: [AFMUG] -48V kicking the dead horse > > Yes. -48VDC means the negative side is hot, and the positive side is ground > (or return). > > You can mix +48VDC and -48VDC if you know what you're doing. It helps a > bunch if the equipment floats logic ground. You need to check to see if your > equipment isolates logic from the supply voltage. > > Yes. Batteries can be grounded either way. They don't care. > > bp > > > On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: >> I know we have been though this many times and I thought I understood it. >> >> -48VDC is the Negative side being HOT, correct? >> >> It is BAD to try to mix -48VDC and 48VDC >> >> There is no such thing as a -48V battery. A battery is a battery, > correct? >> How about the ICT Platinum power supplies. They show as 48VDC, can >> they > be used on -48VDC equipment? >> I remember Check saying something about a way to test to see if a >> piece of > equipment that is Neg 48VDC is truly grounded as Neg 48VDC. >> >> -- >> >> Thanks, >>Mark mailto:m...@mailmt.com >> >> Myakka Communications >> https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.myakka.com%2F&data=05%7C02%7Cbrough%40netblazr.com%7C6c42b49a
Re: [AFMUG] -48V kicking the dead horse
"Ring, Ridge, Red, Right" was the equivalence in the days when Telephone Operator Cord Boards had tip/ring/sleeve connectors on the cords. So Ridge = Red. Thanks Brough From: AF on behalf of Robert Sent: Monday, January 8, 2024 10:32 PM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse But what about Low voltage cable... Is smooth hot or cold or ridged hot or cold? So many choices... LOL.. On 1/8/24 9:39 AM, dmmoff...@gmail.com wrote: > I concur with the wire color problem. > > * My current employer pays big bucks to a low voltage guy who wires up our > sites. His work is absolutely beautiful. It's like friggin artwork. > He uses black for return (+) and green for ground. Then since most of our > equipment has dual power supplies he uses red and blue for the "A" hot and > "B" hot. I assume his employer trained him that way for a reason and that's > probably common. > > * I was taught in childhood that red is positive, so that's what I have > always done. I'm not philosophically opposed to the idea that red is "hot", > but that's just now how I learned it. > > * > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fztlabels.com%2Fblogs%2Fnews%2Fdc-power-circuit-wiring-color-codes&data=05%7C02%7Cbrough%40netblazr.com%7C6c42b49a25dd404e07d908dc1099eb1a%7C06a97f73bf7b45a688f6a3a7bc5f56c7%7C0%7C0%7C638403500474986051%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=NwfihmgJY1P%2FJX8FZ9QQK%2Fbx95TQIV3AqoM5Wowvai0%3D&reserved=0<https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes> > This site advises that for 2-wire DC with positive ground is white for > positive and black for negative. Someone apparently thinks that's the right > way. The same site points out that the only color called out specifically > in the NEC is green or green/yellow for ground. Everything else is just the > convention people landed on. > > Out in the wild you might see anything so there is and will always be a > multi-meter in my everyday toolkit. > > -Adam > > > > -Original Message- > From: AF On Behalf Of Ken Hohhof > Sent: Monday, January 08, 2024 12:01 PM > To: 'AnimalFarm Microwave Users Group' > Subject: Re: [AFMUG] -48V kicking the dead horse > > What I can never decide on is wire colors. Especially when using red/black > zipcord or tray cable. People expect red to be +, but they also expect > black to be ground (except electricians who expect black to be hot and white > to be neutral and green or green/yellow to be ground). And how to > differentiate battery wiring from load wiring. I have not found an ideal > solution other than labels. > > -Original Message- > From: AF On Behalf Of Bill Prince > Sent: Monday, January 8, 2024 10:45 AM > To: af@af.afmug.com > Subject: Re: [AFMUG] -48V kicking the dead horse > > Yes. -48VDC means the negative side is hot, and the positive side is ground > (or return). > > You can mix +48VDC and -48VDC if you know what you're doing. It helps a > bunch if the equipment floats logic ground. You need to check to see if your > equipment isolates logic from the supply voltage. > > Yes. Batteries can be grounded either way. They don't care. > > bp > > > On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: >> I know we have been though this many times and I thought I understood it. >> >> -48VDC is the Negative side being HOT, correct? >> >> It is BAD to try to mix -48VDC and 48VDC >> >> There is no such thing as a -48V battery. A battery is a battery, > correct? >> How about the ICT Platinum power supplies. They show as 48VDC, can >> they > be used on -48VDC equipment? >> I remember Check saying something about a way to test to see if a >> piece of > equipment that is Neg 48VDC is truly grounded as Neg 48VDC. >> >> -- >> >> Thanks, >>Mark mailto:m...@mailmt.com >> >> Myakka Communications >> https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.myakka.com%2F&data=05%7C02%7Cbrough%40netblazr.com%7C6c42b49a25dd404e07d908dc1099eb1a%7C06a97f73bf7b45a688f6a3a7bc5f56c7%7C0%7C0%7C638403500474986051%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=FlUnCHHmZ9Qohes%2BwvKB9GMSitPQuiBOFVDDBFJOdNw%3D&reserved=0<http://www.myakka.com/> >> >> > -- > AF mailing list > AF@af.afmug.com > https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Faf.afmug.com%2Fmailman%2Fl
Re: [AFMUG] -48V kicking the dead horse
But what about Low voltage cable... Is smooth hot or cold or ridged hot or cold? So many choices... LOL.. On 1/8/24 9:39 AM, dmmoff...@gmail.com wrote: I concur with the wire color problem. * My current employer pays big bucks to a low voltage guy who wires up our sites. His work is absolutely beautiful. It's like friggin artwork. He uses black for return (+) and green for ground. Then since most of our equipment has dual power supplies he uses red and blue for the "A" hot and "B" hot. I assume his employer trained him that way for a reason and that's probably common. * I was taught in childhood that red is positive, so that's what I have always done. I'm not philosophically opposed to the idea that red is "hot", but that's just now how I learned it. * https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes This site advises that for 2-wire DC with positive ground is white for positive and black for negative. Someone apparently thinks that's the right way. The same site points out that the only color called out specifically in the NEC is green or green/yellow for ground. Everything else is just the convention people landed on. Out in the wild you might see anything so there is and will always be a multi-meter in my everyday toolkit. -Adam -Original Message- From: AF On Behalf Of Ken Hohhof Sent: Monday, January 08, 2024 12:01 PM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse What I can never decide on is wire colors. Especially when using red/black zipcord or tray cable. People expect red to be +, but they also expect black to be ground (except electricians who expect black to be hot and white to be neutral and green or green/yellow to be ground). And how to differentiate battery wiring from load wiring. I have not found an ideal solution other than labels. -Original Message- From: AF On Behalf Of Bill Prince Sent: Monday, January 8, 2024 10:45 AM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse Yes. -48VDC means the negative side is hot, and the positive side is ground (or return). You can mix +48VDC and -48VDC if you know what you're doing. It helps a bunch if the equipment floats logic ground. You need to check to see if your equipment isolates logic from the supply voltage. Yes. Batteries can be grounded either way. They don't care. bp On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
480 is 277 to ground/neutral and you can find lots of 277 stuff. Even 277-120 control transformers are pretty common. I would not be surprised to see Mean Wells and Tracos having models that will take up to 277. Best Regards, Chuck McCown McCown Technology Corporation 8401 N Commerce Dr Lake Point, Utah 84074 801-250-9503 Office 435-830-4306 Cell www.mccowntech.com www.microtrench.pro www.terabitnetworks.com From: Ken Hohhof Sent: Monday, January 8, 2024 3:06 PM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse We run into this at farms and grain elevators that often have 240 or 480 3-phase. We are on the grain leg at one farm where there is only the 3 legs no neutral. We checked with Phoenix Contact and the power supply we used can accept L1 and L2 on the terminals labeled L and N (actually a Trio DC UPS, this is an old old site). Not sure how common this is, or if our Mean Wells and Tracos would get fried if we tried that. I wish they wouldn’t label one side N if it doesn’t actually have to be the neutral. Most of these sites have an indoor transformer for their 120V lighting and convenience outlets. From: AF On Behalf Of Chuck McCown via AF Sent: Monday, January 8, 2024 3:55 PM To: AnimalFarm Microwave Users Group Cc: ch...@go-mtc.com Subject: Re: [AFMUG] -48V kicking the dead horse Another option, 208 Y but 32 volt boost transformers on devices that need 240. Have done that before too. I always consider boost and buck a slick trick. From: Chuck McCown via AF Sent: Monday, January 8, 2024 2:43 PM To: AnimalFarm Microwave Users Group Cc: ch...@go-mtc.com Subject: Re: [AFMUG] -48V kicking the dead horse You a few choices for 3 phase mixed with 120 single phase. Stinger center tapped winding on a Delta lets you have single phase 120/240 between two legs of the delta. But this also means you have 240 three phase all the way around where many 3 phase loads are nominally spec’d at 208. Probably not a problem but could be for some loads. You also have one leg that is 208 to ground that you might accidentally connect to a 120 device. That is the high leg. Another choice is a 208 Y configuration. Each leg is 120 to ground but two of those 120 legs are 208 across them instead of 240. While many 240 loads will be OK with 208 some will not. All your 208 3 phase loads will be happy. The third choice is a 208 to 240 center tapped transformer. Then your 208 can stay 208 and you can still get true 120/240. The only downside other than the extra expense is the imbalance it puts on the 3 phase line. My shop is full of transformers. 480 to 208. 480 to 240 single phase. Etc. Or you could have the power company give you 3 phase and single phase service without all of this other baloney. From: Mark Radabaugh Sent: Monday, January 8, 2024 2:18 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse On Jan 8, 2024, at 1:54 PM, Ken Hohhof wrote: What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. I don’t think that one is hard to understand, other then the ‘why the hell did someone center tap a delta let anyway?Ok, I have designed systems that way but eventually somebody will blow something up with it given enough time. (it’s useful when you need small quantities of single phase power in an otherwise 3 phase system) Mark -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
We run into this at farms and grain elevators that often have 240 or 480 3-phase. We are on the grain leg at one farm where there is only the 3 legs no neutral. We checked with Phoenix Contact and the power supply we used can accept L1 and L2 on the terminals labeled L and N (actually a Trio DC UPS, this is an old old site). Not sure how common this is, or if our Mean Wells and Tracos would get fried if we tried that. I wish they wouldn’t label one side N if it doesn’t actually have to be the neutral. Most of these sites have an indoor transformer for their 120V lighting and convenience outlets. From: AF On Behalf Of Chuck McCown via AF Sent: Monday, January 8, 2024 3:55 PM To: AnimalFarm Microwave Users Group Cc: ch...@go-mtc.com Subject: Re: [AFMUG] -48V kicking the dead horse Another option, 208 Y but 32 volt boost transformers on devices that need 240. Have done that before too. I always consider boost and buck a slick trick. From: Chuck McCown via AF Sent: Monday, January 8, 2024 2:43 PM To: AnimalFarm Microwave Users Group Cc: ch...@go-mtc.com <mailto:ch...@go-mtc.com> Subject: Re: [AFMUG] -48V kicking the dead horse You a few choices for 3 phase mixed with 120 single phase. Stinger center tapped winding on a Delta lets you have single phase 120/240 between two legs of the delta. But this also means you have 240 three phase all the way around where many 3 phase loads are nominally spec’d at 208. Probably not a problem but could be for some loads. You also have one leg that is 208 to ground that you might accidentally connect to a 120 device. That is the high leg. Another choice is a 208 Y configuration. Each leg is 120 to ground but two of those 120 legs are 208 across them instead of 240. While many 240 loads will be OK with 208 some will not. All your 208 3 phase loads will be happy. The third choice is a 208 to 240 center tapped transformer. Then your 208 can stay 208 and you can still get true 120/240. The only downside other than the extra expense is the imbalance it puts on the 3 phase line. My shop is full of transformers. 480 to 208. 480 to 240 single phase. Etc. Or you could have the power company give you 3 phase and single phase service without all of this other baloney. From: Mark Radabaugh Sent: Monday, January 8, 2024 2:18 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse On Jan 8, 2024, at 1:54 PM, Ken Hohhof mailto:khoh...@kwom.com> > wrote: What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. I don’t think that one is hard to understand, other then the ‘why the hell did someone center tap a delta let anyway?Ok, I have designed systems that way but eventually somebody will blow something up with it given enough time. (it’s useful when you need small quantities of single phase power in an otherwise 3 phase system) Mark _ -- AF mailing list AF@af.afmug.com <mailto:AF@af.afmug.com> http://af.afmug.com/mailman/listinfo/af_af.afmug.com _ -- AF mailing list AF@af.afmug.com <mailto:AF@af.afmug.com> http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
Another option, 208 Y but 32 volt boost transformers on devices that need 240. Have done that before too. I always consider boost and buck a slick trick. From: Chuck McCown via AF Sent: Monday, January 8, 2024 2:43 PM To: AnimalFarm Microwave Users Group Cc: ch...@go-mtc.com Subject: Re: [AFMUG] -48V kicking the dead horse You a few choices for 3 phase mixed with 120 single phase. Stinger center tapped winding on a Delta lets you have single phase 120/240 between two legs of the delta. But this also means you have 240 three phase all the way around where many 3 phase loads are nominally spec’d at 208. Probably not a problem but could be for some loads. You also have one leg that is 208 to ground that you might accidentally connect to a 120 device. That is the high leg. Another choice is a 208 Y configuration. Each leg is 120 to ground but two of those 120 legs are 208 across them instead of 240. While many 240 loads will be OK with 208 some will not. All your 208 3 phase loads will be happy. The third choice is a 208 to 240 center tapped transformer. Then your 208 can stay 208 and you can still get true 120/240. The only downside other than the extra expense is the imbalance it puts on the 3 phase line. My shop is full of transformers. 480 to 208. 480 to 240 single phase. Etc. Or you could have the power company give you 3 phase and single phase service without all of this other baloney. From: Mark Radabaugh Sent: Monday, January 8, 2024 2:18 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse On Jan 8, 2024, at 1:54 PM, Ken Hohhof wrote: What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. I don’t think that one is hard to understand, other then the ‘why the hell did someone center tap a delta let anyway?Ok, I have designed systems that way but eventually somebody will blow something up with it given enough time. (it’s useful when you need small quantities of single phase power in an otherwise 3 phase system) Mark -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
You a few choices for 3 phase mixed with 120 single phase. Stinger center tapped winding on a Delta lets you have single phase 120/240 between two legs of the delta. But this also means you have 240 three phase all the way around where many 3 phase loads are nominally spec’d at 208. Probably not a problem but could be for some loads. You also have one leg that is 208 to ground that you might accidentally connect to a 120 device. That is the high leg. Another choice is a 208 Y configuration. Each leg is 120 to ground but two of those 120 legs are 208 across them instead of 240. While many 240 loads will be OK with 208 some will not. All your 208 3 phase loads will be happy. The third choice is a 208 to 240 center tapped transformer. Then your 208 can stay 208 and you can still get true 120/240. The only downside other than the extra expense is the imbalance it puts on the 3 phase line. My shop is full of transformers. 480 to 208. 480 to 240 single phase. Etc. Or you could have the power company give you 3 phase and single phase service without all of this other baloney. From: Mark Radabaugh Sent: Monday, January 8, 2024 2:18 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse On Jan 8, 2024, at 1:54 PM, Ken Hohhof wrote: What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. I don’t think that one is hard to understand, other then the ‘why the hell did someone center tap a delta let anyway?Ok, I have designed systems that way but eventually somebody will blow something up with it given enough time. (it’s useful when you need small quantities of single phase power in an otherwise 3 phase system) Mark -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
> On Jan 8, 2024, at 1:54 PM, Ken Hohhof wrote: > > What I always have a hard time wrapping my head around is 240/120/208 wild > leg delta. > I don’t think that one is hard to understand, other then the ‘why the hell did someone center tap a delta let anyway?Ok, I have designed systems that way but eventually somebody will blow something up with it given enough time. (it’s useful when you need small quantities of single phase power in an otherwise 3 phase system) Mark -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
My rule for DC plants is BLACK == Ground Referenced side. On Mon, Jan 8, 2024 at 11:02 AM Ken Hohhof wrote: > What I can never decide on is wire colors. Especially when using red/black > zipcord or tray cable. People expect red to be +, but they also expect > black to be ground (except electricians who expect black to be hot and > white > to be neutral and green or green/yellow to be ground). And how to > differentiate battery wiring from load wiring. I have not found an ideal > solution other than labels. > > -Original Message- > From: AF On Behalf Of Bill Prince > Sent: Monday, January 8, 2024 10:45 AM > To: af@af.afmug.com > Subject: Re: [AFMUG] -48V kicking the dead horse > > Yes. -48VDC means the negative side is hot, and the positive side is ground > (or return). > > You can mix +48VDC and -48VDC if you know what you're doing. It helps a > bunch if the equipment floats logic ground. You need to check to see if > your > equipment isolates logic from the supply voltage. > > Yes. Batteries can be grounded either way. They don't care. > > bp > > > On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: > > I know we have been though this many times and I thought I understood it. > > > > -48VDC is the Negative side being HOT, correct? > > > > It is BAD to try to mix -48VDC and 48VDC > > > > There is no such thing as a -48V battery. A battery is a battery, > correct? > > > > How about the ICT Platinum power supplies. They show as 48VDC, can they > be used on -48VDC equipment? > > > > I remember Check saying something about a way to test to see if a piece > of > equipment that is Neg 48VDC is truly grounded as Neg 48VDC. > > > > > > -- > > > > Thanks, > > Mark mailto:m...@mailmt.com > > > > Myakka Communications > > www.Myakka.com > > > > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- Carl Peterson *PORT NETWORKS* 401 E Pratt St, Ste 2553 Baltimore, MD 21202 (410) 637-3707 -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
Have to have a chalk board to show the wild leg thing. I got my 3 phase down pretty cold now. Had an electrician wire up a receptacle to the wild leg once. Blew up a transformer. That was my first exposure to a wild leg. From: Ken Hohhof Sent: Monday, January 8, 2024 11:54 AM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse I would think many of us have both 24V and 48V in the same rack or cabinet. We started out 24V, then mixed, now able to do most sites all 48V, but lots of mixed 24 and 48 out there. I think of -48 as just another voltage to keep straight. If I power a radio or router with 48-56 volts that is intended for 24-30V, bad things will happen. Not sure what there is about polarity that drives people crazy. What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. From: AF On Behalf Of castarritt Sent: Monday, January 8, 2024 12:35 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse The ICT shelves come in both +48v and -48v flavors. Usually the positive version has a P on the end of the model. An ICT-2U4 would be negative, and an ICT-2U4P is positive. You can mix both -48 and +48 loads at one site, but you need an isolated DC-DC converter such as a Meanwell RSD-500C-48. On Mon, Jan 8, 2024 at 10:26 AM Mark - Myakka Technologies wrote: I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
I would think many of us have both 24V and 48V in the same rack or cabinet. We started out 24V, then mixed, now able to do most sites all 48V, but lots of mixed 24 and 48 out there. I think of -48 as just another voltage to keep straight. If I power a radio or router with 48-56 volts that is intended for 24-30V, bad things will happen. Not sure what there is about polarity that drives people crazy. What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. From: AF On Behalf Of castarritt Sent: Monday, January 8, 2024 12:35 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse The ICT shelves come in both +48v and -48v flavors. Usually the positive version has a P on the end of the model. An ICT-2U4 would be negative, and an ICT-2U4P is positive. You can mix both -48 and +48 loads at one site, but you need an isolated DC-DC converter such as a Meanwell RSD-500C-48. On Mon, Jan 8, 2024 at 10:26 AM Mark - Myakka Technologies mailto:m...@mailmt.com> > wrote: I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com <mailto:m...@mailmt.com> Myakka Communications www.Myakka.com <http://www.Myakka.com> -- AF mailing list AF@af.afmug.com <mailto:AF@af.afmug.com> http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
The ICT shelves come in both +48v and -48v flavors. Usually the positive version has a P on the end of the model. An ICT-2U4 would be negative, and an ICT-2U4P is positive. You can mix both -48 and +48 loads at one site, but you need an isolated DC-DC converter such as a Meanwell RSD-500C-48. On Mon, Jan 8, 2024 at 10:26 AM Mark - Myakka Technologies wrote: > I know we have been though this many times and I thought I understood it. > > -48VDC is the Negative side being HOT, correct? > > It is BAD to try to mix -48VDC and 48VDC > > There is no such thing as a -48V battery. A battery is a battery, correct? > > How about the ICT Platinum power supplies. They show as 48VDC, can they > be used on -48VDC equipment? > > I remember Check saying something about a way to test to see if a piece of > equipment that is Neg 48VDC is truly grounded as Neg 48VDC. > > > -- > > Thanks, > Mark mailto:m...@mailmt.com > > Myakka Communications > www.Myakka.com > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
The issue is if the power supply or any of the equipment connected to it has positive tied to ground and then you take another device with negative tied to ground and put that on the same power supply. Then you have + and - of the power supply dead shorted through the ground connections and that's when the sparks fly. Some people keep the -48V stuff in a separate rack. That's not necessary, but it's not a bad safety measure if you have happen to have enough space for two racks. It's nice to say If the equipment has - tied to ground or tied to the chassis then it has to be isolated from your -48V power supply. You can still put it in the same rack as everything else, but it needs a separate power supply isolated from your -48V power system. So you get an isolated 48V to 48V power supply (Meanwell RSD-300C-48 is one example), or you plug that one device into an A/C outlet or inverter or what have you. I have test ONT's with -ground sitting in the rack with with a bunch of -48V (+ground) routers and it's all fine because they have their little DC transformers plugged into a wall outlet. Someone said this, but to check if the equipment has a ground reference set your multimeter for ohms and measure from each power input to the ground lug and/or chassis of the device. If you're reading an open circuit then you're fine. You're probably fine if you're reading a very large number of ohms --I'd hate to give a specific number and say that's always safe, but the Meanwell RSD I mentioned above is 100M Ohms from Input to Output per the datasheet and that device has not failed me. If you're seeing 0 or single digits from one of the power leads to ground then you have power bonded to ground on that device. An example fresh in my mind is Mikrotik CRS305 has - tied to ground, so although it will run on 48V I could not put it on our -48V rectifier. Lots of equipment intended for telecom will have + connected to ground. Also lots of equipment will have neither tied to ground and those often work with either +V or -V (but I'd go by what the manufacturer says first, and by the multimeter second). -Adam -Original Message- From: AF On Behalf Of Mark - Myakka Technologies Sent: Monday, January 08, 2024 11:26 AM To: af@af.afmug.com Subject: [AFMUG] -48V kicking the dead horse I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
I would be more than happy with that scheme. Look up at a fuse or CB panel, see red and blue and you immediately know what you are working with. -Original Message- From: dmmoff...@gmail.com Sent: Monday, January 8, 2024 10:39 AM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse I concur with the wire color problem. * My current employer pays big bucks to a low voltage guy who wires up our sites. His work is absolutely beautiful. It's like friggin artwork. He uses black for return (+) and green for ground. Then since most of our equipment has dual power supplies he uses red and blue for the "A" hot and "B" hot. I assume his employer trained him that way for a reason and that's probably common. * I was taught in childhood that red is positive, so that's what I have always done. I'm not philosophically opposed to the idea that red is "hot", but that's just now how I learned it. * https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes This site advises that for 2-wire DC with positive ground is white for positive and black for negative. Someone apparently thinks that's the right way. The same site points out that the only color called out specifically in the NEC is green or green/yellow for ground. Everything else is just the convention people landed on. Out in the wild you might see anything so there is and will always be a multi-meter in my everyday toolkit. -Adam -Original Message- From: AF On Behalf Of Ken Hohhof Sent: Monday, January 08, 2024 12:01 PM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse What I can never decide on is wire colors. Especially when using red/black zipcord or tray cable. People expect red to be +, but they also expect black to be ground (except electricians who expect black to be hot and white to be neutral and green or green/yellow to be ground). And how to differentiate battery wiring from load wiring. I have not found an ideal solution other than labels. -Original Message- From: AF On Behalf Of Bill Prince Sent: Monday, January 8, 2024 10:45 AM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse Yes. -48VDC means the negative side is hot, and the positive side is ground (or return). You can mix +48VDC and -48VDC if you know what you're doing. It helps a bunch if the equipment floats logic ground. You need to check to see if your equipment isolates logic from the supply voltage. Yes. Batteries can be grounded either way. They don't care. bp On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
I concur with the wire color problem. * My current employer pays big bucks to a low voltage guy who wires up our sites. His work is absolutely beautiful. It's like friggin artwork. He uses black for return (+) and green for ground. Then since most of our equipment has dual power supplies he uses red and blue for the "A" hot and "B" hot. I assume his employer trained him that way for a reason and that's probably common. * I was taught in childhood that red is positive, so that's what I have always done. I'm not philosophically opposed to the idea that red is "hot", but that's just now how I learned it. * https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes This site advises that for 2-wire DC with positive ground is white for positive and black for negative. Someone apparently thinks that's the right way. The same site points out that the only color called out specifically in the NEC is green or green/yellow for ground. Everything else is just the convention people landed on. Out in the wild you might see anything so there is and will always be a multi-meter in my everyday toolkit. -Adam -Original Message- From: AF On Behalf Of Ken Hohhof Sent: Monday, January 08, 2024 12:01 PM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse What I can never decide on is wire colors. Especially when using red/black zipcord or tray cable. People expect red to be +, but they also expect black to be ground (except electricians who expect black to be hot and white to be neutral and green or green/yellow to be ground). And how to differentiate battery wiring from load wiring. I have not found an ideal solution other than labels. -Original Message- From: AF On Behalf Of Bill Prince Sent: Monday, January 8, 2024 10:45 AM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse Yes. -48VDC means the negative side is hot, and the positive side is ground (or return). You can mix +48VDC and -48VDC if you know what you're doing. It helps a bunch if the equipment floats logic ground. You need to check to see if your equipment isolates logic from the supply voltage. Yes. Batteries can be grounded either way. They don't care. bp On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: > I know we have been though this many times and I thought I understood it. > > -48VDC is the Negative side being HOT, correct? > > It is BAD to try to mix -48VDC and 48VDC > > There is no such thing as a -48V battery. A battery is a battery, correct? > > How about the ICT Platinum power supplies. They show as 48VDC, can > they be used on -48VDC equipment? > > I remember Check saying something about a way to test to see if a > piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. > > > -- > > Thanks, > Mark mailto:m...@mailmt.com > > Myakka Communications > www.Myakka.com > > -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
I literally smoked a digital COE switch due to this one time. I have seen Blue for hot and Red for return -48 I have seen Blue for hot and Black for return -48 Black for hot and Red for return in a -48 system. Which would make that one Red+ and Black - but positive ground. Red for hot and Black for a return in many + and - systems. So red is + in some systems and - in others. I think I prefer red and black with red being positive and then you have to have enough brains to know that it is also return and usually ground with black being hot. Should not be a stretch due to residential 120 VAC has black being hot. So there, all confusion has now been erased... right... -Original Message- From: Ken Hohhof Sent: Monday, January 8, 2024 10:00 AM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] -48V kicking the dead horse What I can never decide on is wire colors. Especially when using red/black zipcord or tray cable. People expect red to be +, but they also expect black to be ground (except electricians who expect black to be hot and white to be neutral and green or green/yellow to be ground). And how to differentiate battery wiring from load wiring. I have not found an ideal solution other than labels. -Original Message- From: AF On Behalf Of Bill Prince Sent: Monday, January 8, 2024 10:45 AM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse Yes. -48VDC means the negative side is hot, and the positive side is ground (or return). You can mix +48VDC and -48VDC if you know what you're doing. It helps a bunch if the equipment floats logic ground. You need to check to see if your equipment isolates logic from the supply voltage. Yes. Batteries can be grounded either way. They don't care. bp On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
What I can never decide on is wire colors. Especially when using red/black zipcord or tray cable. People expect red to be +, but they also expect black to be ground (except electricians who expect black to be hot and white to be neutral and green or green/yellow to be ground). And how to differentiate battery wiring from load wiring. I have not found an ideal solution other than labels. -Original Message- From: AF On Behalf Of Bill Prince Sent: Monday, January 8, 2024 10:45 AM To: af@af.afmug.com Subject: Re: [AFMUG] -48V kicking the dead horse Yes. -48VDC means the negative side is hot, and the positive side is ground (or return). You can mix +48VDC and -48VDC if you know what you're doing. It helps a bunch if the equipment floats logic ground. You need to check to see if your equipment isolates logic from the supply voltage. Yes. Batteries can be grounded either way. They don't care. bp On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: > I know we have been though this many times and I thought I understood it. > > -48VDC is the Negative side being HOT, correct? > > It is BAD to try to mix -48VDC and 48VDC > > There is no such thing as a -48V battery. A battery is a battery, correct? > > How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? > > I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. > > > -- > > Thanks, > Mark mailto:m...@mailmt.com > > Myakka Communications > www.Myakka.com > > -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
I mixed + and - 48 in a off grid solar system. I had one battery bank with the positive to the common point/ ground. The other battery bank was negative to the common point. From one battery to the other it was 96 volts when went to the load. But I had two 48 volt solar systems and charge controllers and they charged each half of the total battery independently. One of the charge controllers had to be mounted on an insulating board because its chassis was hot. The whole -48, +48 thing is all about what is connected to the ground, common point, return etc. If you ground the negative side of a battery you have a positive voltage hot wire system. If you ground the positive side of a battery you have a negative voltage hot wire. The battery itself does not care. If you load does not have an electrical connection to a grounded chassis, it will not car either. However if you have a device that is designed to be powered from -48 and internally its positive 48 connections are all bonded to its metallic chassis, it really needs to be powered from a floating supply or a -48 supply. There is no good reason to ground either side of a DC supply in a system these days. Originally telcos went with positive grounding so that if you had an insulation fault in an underground cable, the -48 volt ring side (hot side) of the phone line would tend to attract metallic ions from the surrounding soil. If it was reversed the wire would donate copper ions to the soil and quickly plate itself away to nothingness. -Original Message- From: Mark - Myakka Technologies Sent: Monday, January 8, 2024 9:25 AM To: af@af.afmug.com Subject: [AFMUG] -48V kicking the dead horse I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
Yes. -48VDC means the negative side is hot, and the positive side is ground (or return). You can mix +48VDC and -48VDC if you know what you're doing. It helps a bunch if the equipment floats logic ground. You need to check to see if your equipment isolates logic from the supply voltage. Yes. Batteries can be grounded either way. They don't care. bp On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote: I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
Most AC/DC and DC/DC power supplies have input/output isolation and neither side of the output grounded unless/until you ground one side. If you ground the - side, then it's referred to as +48V. If you ground the + side, then it's -48V. Fancier equipment with stuff like management interfaces may be dedicated as +48V or -48V, I have an Eltek Micropack system that can only be used as -48V. Lots of stuff from the telecom world may be that way. Something like a Mean Well power supply will almost certainly be floating until you ground one side of the output. I know a WISP guy who tends to power all his DC+fiber radios with individual AC/DC power supplies and doesn't ground them. I am a traditionalist and want all my power supplies ground referenced, but it seems to work for him. I guess you could argue it prevents ground loops. Where we typically run into problems is with the loads like radios and routers, sometimes they are floating and don't care, some have the + side grounded, some have the - side grounded. Chuck was probably saying to check with an ohmmeter from DC+ and DC- to chassis ground. I have also been lucky that when I got it wrong, it just popped a fuse and no magic smoke escaped. Hopefully you individually fuse all your loads. -Original Message- From: AF On Behalf Of Mark - Myakka Technologies Sent: Monday, January 8, 2024 10:26 AM To: af@af.afmug.com Subject: [AFMUG] -48V kicking the dead horse I know we have been though this many times and I thought I understood it. -48VDC is the Negative side being HOT, correct? It is BAD to try to mix -48VDC and 48VDC There is no such thing as a -48V battery. A battery is a battery, correct? How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? I remember Check saying something about a way to test to see if a piece of equipment that is Neg 48VDC is truly grounded as Neg 48VDC. -- Thanks, Mark mailto:m...@mailmt.com Myakka Communications www.Myakka.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
Re: [AFMUG] -48V kicking the dead horse
>It is BAD to try to mix -48VDC and 48VDC Very >There is no such thing as a -48V battery. A battery is a battery, correct? Correct. You still wire + to + and - to - >How about the ICT Platinum power supplies. They show as 48VDC, can they be used on -48VDC equipment? Pretty confident, this is their industry. Cliff is my contact who can confirm. On Mon, Jan 8, 2024 at 11:27 AM Mark - Myakka Technologies wrote: > I know we have been though this many times and I thought I understood it. > > -48VDC is the Negative side being HOT, correct? > > It is BAD to try to mix -48VDC and 48VDC > > There is no such thing as a -48V battery. A battery is a battery, correct? > > How about the ICT Platinum power supplies. They show as 48VDC, can they > be used on -48VDC equipment? > > I remember Check saying something about a way to test to see if a piece of > equipment that is Neg 48VDC is truly grounded as Neg 48VDC. > > > -- > > Thanks, > Mark mailto:m...@mailmt.com > > Myakka Communications > www.Myakka.com > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
