Re: nanog [really inspectors & MOV's]
Speaking on Deep Background, the Press Secretary whispered: > > > Virtually all surge protectors have MOV - Metal Oxide Varisters - > > within. These are devices with s sharp knee on their Voltage vs > > Resistance curve. In other words, they do not conduct for a 120V > > level, but do at 200, shunting that overvoltage to ground. > > Careful: that conduction voltage is peak, is it not? Some Marketing Dude must have decided that such was too complex for customers So the traditional MOV part # is a f(RMS working voltage) NOT the peak where it conducts... Grr Gnash Argh!!! Note the "customer" is a design engineer... > Smoke emitting diodes? MOV's are bipolar... > > But note that the OP does not have a MOV issue; he has an inspector > > issue. His best answer there may be buying outlet strips that > > offer no surge protection. He likely will need to first pin > > the inspector down on what rules he's allegely broken, however. > > This is the most cogent point to date, and the one I made off list: ask > him to quote chapter and verse. And be sure it's not an Alexander Hamilton type issue.. -- A host is a host from coast to [EMAIL PROTECTED] & no one will talk to a host that's close[v].(301) 56-LINUX Unless the host (that isn't close).pob 1433 is busy, hung or dead20915-1433
Re: nanog
--On Sunday, March 13, 2005 10:28 PM -0500 "Jay R. Ashworth" <[EMAIL PROTECTED]> wrote: But note that the OP does not have a MOV issue; he has an inspector issue. His best answer there may be buying outlet strips that offer no surge protection. He likely will need to first pin the inspector down on what rules he's allegely broken, however. This is the most cogent point to date, and the one I made off list: ask him to quote chapter and verse. Yeah, I am waiting on the exact code violation to come down. FWIW the overall consent from various fire marshalls is 'yes, it's fine' but some had misgivings about it. understandable, and strictly according to atleast one rule book it isn't allowed.
Re: nanog
On Sun, Mar 13, 2005 at 06:12:46PM -0500, David Lesher wrote: > Speaking on Deep Background, the Press Secretary whispered: > > Perhaps someone who knows EE can enlighten me? > > I'll try. > > The #1) is BS. #2) is true. > > If ANYTHING is, it's square waves. [Huh?] > > Virtually all surge protectors have MOV - Metal Oxide Varisters - > within. These are devices with s sharp knee on their Voltage vs > Resistance curve. In other words, they do not conduct for a 120V > level, but do at 200, shunting that overvoltage to ground. Careful: that conduction voltage is peak, is it not? 120VAC is RMS; the peack voltage is, like, 175, isn't it? > Now, via magic called Fourier, sharp transitions mean lots of short, > high voltage pieces-parts. [trust me, or read up..you can create > any square wave from an infinite series of sine waves..] > > So the ""risk"" I hear talk about is this. The MOV's in a strip > conduct slightly on those squarewavish USP output waveforms. This > results in 2 things, gradual loss of MOV efficacy, as they > degrade slowly with use; and the worry that iffen the MOV's > absorb too much squarewave crap, they'll explode. See, MOV's > turn transients into heat. Line transients are assumed to be err > transient & tolerable. Continuous stuff is another issue...that > can overheat the MOV and cause it to worship the Smoke God. Smoke emitting diodes? > So let's ban surge strips on UPS's...But wait... lots of machines > have MOV's inside their power supplies.. Shhh!!! :-) > But note that the OP does not have a MOV issue; he has an inspector > issue. His best answer there may be buying outlet strips that > offer no surge protection. He likely will need to first pin > the inspector down on what rules he's allegely broken, however. This is the most cogent point to date, and the one I made off list: ask him to quote chapter and verse. Cheers, -- jra -- Jay R. Ashworth[EMAIL PROTECTED] Designer Baylink RFC 2100 Ashworth & AssociatesThe Things I Think'87 e24 St Petersburg FL USA http://baylink.pitas.com +1 727 647 1274 If you can read this... thank a system adminstrator. Or two. --me
nanog
Speaking on Deep Background, the Press Secretary whispered:
>
>
>
> Perhaps someone who knows EE can enlighten me?
I'll try.
The #1) is BS. #2) is true.
If ANYTHING is, it's square waves. [Huh?]
Virtually all surge protectors have MOV - Metal Oxide Varisters -
within. These are devices with s sharp knee on their Voltage vs
Resistance curve. In other words, they do not conduct for a 120V
level, but do at 200, shunting that overvoltage to ground.
Line power is a sine wave. The cheapest inverters make square
waves {because it's how an inverter works; one transistor comes on,
making a positive-going waveform; the second one takes its turn,
making a negative-going one. Back and forth.} But the transitions
are quite abrupt. Better UPS's use a stepped squarewave, maybe
3 levels, instead of one. The be$t make sine waves...
[Side note: the usual switcher supply on a PC/Sun/etc does not
give a damn re: sine vs square wave; as the first thing it does
is make DC out of the AC and filter it..]
Now, via magic called Fourier, sharp transitions mean lots of short,
high voltage pieces-parts. [trust me, or read up..you can create
any square wave from an infinite series of sine waves..]
So the ""risk"" I hear talk about is this. The MOV's in a strip
conduct slightly on those squarewavish USP output waveforms. This
results in 2 things, gradual loss of MOV efficacy, as they
degrade slowly with use; and the worry that iffen the MOV's
absorb too much squarewave crap, they'll explode. See, MOV's
turn transients into heat. Line transients are assumed to be err
transient & tolerable. Continuous stuff is another issue...that
can overheat the MOV and cause it to worship the Smoke God.
But then, so do big power hits. If you ever shake a strip and hear
it rattle, the MOV's were #1 on the Smoke God's list. And in the
WORST cases, the heat melts the plastic strip/sets it on fire.
So let's ban surge strips on UPS's...But wait... lots of machines
have MOV's inside their power supplies.. Shhh!!!
But note that the OP does not have a MOV issue; he has an inspector
issue. His best answer there may be buying outlet strips that
offer no surge protection. He likely will need to first pin
the inspector down on what rules he's allegely broken, however.
--
A host is a host from coast to [EMAIL PROTECTED]
& no one will talk to a host that's close[v].(301) 56-LINUX
Unless the host (that isn't close).pob 1433
is busy, hung or dead20915-1433
Re: Fire Code/UFC Regs?
At 09:08 AM 3/13/2005, Josh Vince wrote: Here's what APC has to say about it: http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_sid=jTAq9iAh&p_lva=&p_faqid=1372&p_created=1010390400&p_sp=cF9zcmNoPTEmcF9ncmlkc29ydD0mcF9yb3dfY250PTM4NyZwX3NlYXJjaF90ZXh0PXN1cmdlIGludG8gVVBTJnBfc2VhcmNoX3R5cGU9MyZwX3Byb2RfbHZsMT1_YW55fiZwX3Byb2RfbHZsMj1_YW55fiZwX3BhZ2U9Mg**&p_li= Sorry about the wrap... Basically, they say not to plug surge strips into the output of a UPS. You should use PDU's instead. Or, more basically: Buy APC's power strips, because we think we engineered them correctly, and think nobody else possibly could design a decent power strip. Here's a URL showing some of their rack mounted PDU products http://www.apc.com/products/family/index.cfm?id=30 While I like APC products, I have to wonder whether this "requirement" for using only "PDU" products was written by their lawyers to cover liability concerns when someone uses a low-quality power strip, and/or their marketing folks to push their own power strips. Josh On Fri, 11 Mar 2005 11:46:50 -0700, Michael Loftis <[EMAIL PROTECTED]> wrote: > > OK this is only probably marginally operational. Yesterday we were > inspected (quite thoroughly I might add.) by the city fire inspector > for Missoula, MTNow we did have a couple of things I know need fixing, > an emergency light with a dead battery upstairs, I'm using a long orange > extension cord w/o a breaker on it for my monitor at my desk. And one > incidence where we had some piggy-backing going on. > > Now what I'm asking is this: we were told that you can NOT plug in breaker > protected six outlet strips into battery backup units such as APCs, and we > were (or are) being written up for that. My understanding is that most/all > (atleast APC units) are properly de-rated (per UFC) and you *can* plug in > additional breaker protected extension cords into these units. > > The problem is if this is not the case we'll be having to put a LOT more > BBUs out into our office for workstations than what we planned. I've also > never seen this cited as a problem but I could just be ignorant too. > > Please reply off-list. Sorry if anyone feels like this is a waste of time, > but if there is interest I will summarize on list. > > If this really is true then I can see a lot of places breaking this fire > code even here locally. I'm not sure what part of the code it is but he's > stated that if I can get him some form of documentation from teh > manufacturer or something then he can make a deviation. With a 2200VA unit > only having 4-6 outlets on it I can't see *not* using additional power > strip off the back of it. > > Thanks guys, back to the regular NANOG channel... > > -- > GPG/PGP --> 0xE736BD7E 5144 6A2D 977A 6651 DFBE 1462 E351 88B9 E736 BD7E >
Re: Fire Code/UFC Regs?
Perhaps someone who knows EE can enlighten me? Joe OK - my considered opinion as a BSEE is: It's a pile of BS designed to sell PDU's. "but do not efficiently distribute the power, meaning that some equipment may be deprived of the necessary amperage it requires to run properly" Yeah. Sure. Mark Radabaugh
Re: Fire Code/UFC Regs?
Josh Vince wrote: Here's what APC has to say about it: http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_sid=jTAq9iAh&p_lva=&p_faqid=1372&p_created=1010390400&p_sp=cF9zcmNoPTEmcF9ncmlkc29ydD0mcF9yb3dfY250PTM4NyZwX3NlYXJjaF90ZXh0PXN1cmdlIGludG8gVVBTJnBfc2VhcmNoX3R5cGU9MyZwX3Byb2RfbHZsMT1_YW55fiZwX3Byb2RfbHZsMj1_YW55fiZwX3BhZ2U9Mg**&p_li= Sorry about the wrap... Basically, they say not to plug surge strips into the output of a UPS. You should use PDU's instead. Josh Summary I read: PowerStrips/Surge protectors are junky things which dont distribute voltage/amperage equaly, so you should not use them with a UPS. 1) How does this stated/assumed condition become more relevant for a UPS than for any other use? 2) I highly doubt that such a blanket assumption can be made about the literally thousands of branded surge protecters and power strips. 3) They admit that they are talking out of their a** when they say this does not affect the warranty. 4) Since the odds are fairly strong that any device that draws 15-20 Amps * 110 volts in wattage will cause (most) batteries to go overload, I see no specific reason to be concerned that other devices on the strip may not get enough juice. In short, that would be the least of my problems. 5) Having surge protectors IS good. Now any device that overloads/makes the circtuit too warm shuts itself off. Everything else on the battery hums along merrily. Just like my kids flipping the AC on and off repeatedly.surge cuts it off and my computer continues merrily on. How does the battery deal with equipment that tries to draw surges of power. I dont see anything valid there. But more to the point I dont see anything that would explain it being against regs. Perhaps someone who knows EE can enlighten me? Joe
Re: Fire Code/UFC Regs?
Here's what APC has to say about it: http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_sid=jTAq9iAh&p_lva=&p_faqid=1372&p_created=1010390400&p_sp=cF9zcmNoPTEmcF9ncmlkc29ydD0mcF9yb3dfY250PTM4NyZwX3NlYXJjaF90ZXh0PXN1cmdlIGludG8gVVBTJnBfc2VhcmNoX3R5cGU9MyZwX3Byb2RfbHZsMT1_YW55fiZwX3Byb2RfbHZsMj1_YW55fiZwX3BhZ2U9Mg**&p_li= Sorry about the wrap... Basically, they say not to plug surge strips into the output of a UPS. You should use PDU's instead. Josh On Fri, 11 Mar 2005 11:46:50 -0700, Michael Loftis <[EMAIL PROTECTED]> wrote: > > OK this is only probably marginally operational. Yesterday we were > inspected (quite thoroughly I might add.) by the city fire inspector > for Missoula, MTNow we did have a couple of things I know need fixing, > an emergency light with a dead battery upstairs, I'm using a long orange > extension cord w/o a breaker on it for my monitor at my desk. And one > incidence where we had some piggy-backing going on. > > Now what I'm asking is this: we were told that you can NOT plug in breaker > protected six outlet strips into battery backup units such as APCs, and we > were (or are) being written up for that. My understanding is that most/all > (atleast APC units) are properly de-rated (per UFC) and you *can* plug in > additional breaker protected extension cords into these units. > > The problem is if this is not the case we'll be having to put a LOT more > BBUs out into our office for workstations than what we planned. I've also > never seen this cited as a problem but I could just be ignorant too. > > Please reply off-list. Sorry if anyone feels like this is a waste of time, > but if there is interest I will summarize on list. > > If this really is true then I can see a lot of places breaking this fire > code even here locally. I'm not sure what part of the code it is but he's > stated that if I can get him some form of documentation from teh > manufacturer or something then he can make a deviation. With a 2200VA unit > only having 4-6 outlets on it I can't see *not* using additional power > strip off the back of it. > > Thanks guys, back to the regular NANOG channel... > > -- > GPG/PGP --> 0xE736BD7E 5144 6A2D 977A 6651 DFBE 1462 E351 88B9 E736 BD7E >
Re: IRC bots...
On Sat, 12 Mar 2005, John Kristoff wrote: Tallying then just the TCP 6667 traffic, perhaps eliminating very short lived or small flows, should be a good indicator of IRC traffic usage, but tagging those as potential sources for problems may be Yes and no, in my experience. Depending on the drone, some connect to a server and stay connected. You could say the inverse is true, and look for long connections, but that will likely snare you legitimate traffic from the screen-running nerd set. difficult. Perhaps in environments where IRC as an application is strictly forbidden or blocked this will work well, but on more open and larger network this may waste time, not save it. Since in the latter case, figuring out what is legit and what is not will likely be a lot of leg work. This is why I suggested a snort filter, to actually inspect the packet traffic. Watching IRC traffic is only valid so long as the standard ports are being honored. What about bounces, and non-standard traffic? You need to go after the single common property, the protocol itself. Even so, you're still in an arms race. You can automate some of this further, by building white lists or black lists of IRC server addresses. A white list doesn't tend to scale very well. A black list scales better, but you have to get those black listed addresses and doing that part is harder. There are some people/groups who spend time finding black list hosts so leveraging their data can be very useful and time saving. This will backfire, in my opinion. Many drone nets hide in plain sight, connecting to public IRC networks where they can't reliably be traced to an authoritative user. You'll bejuggling access to public resources, and that's a waste of energy, I think. - billn
