Mark's answer matches what my recommendation would be. I'd just use the same sized conductor for ground that you used for the circuit itself, and make sure that the breaker is sized correctly (meaning not too large) for the wire run. I would probably put a 15A breaker in back at the panel, even with a 10GA run, unless you needed >15A for some reason, at which point I'd run 230V and step it down at the tower. The purpose of sizing the breaker down is to better match the actual capacity of the circuit at that distance.
It sounds like the expert in this case has somehow gotten the idea that the only acceptable solution is to have a single low-impedance ground system which encompasses the entire system, including the panel. To do this effectively, you *would* have to have a large conductor so that effectively all grounding points are electrically identical. However, in this case, it's probably better to treat it as two separate grounding systems, with a higher-impedance (resistance) grounding path between them which will serve the purpose of allowing the circuit breaker to clear a phase-to-ground fault by tripping, but not encourage surges to travel between the two systems - you want tower system surges to go into the tower ground, and the electrical system surges to go into the electrical ground. Alternatively you could include a transformer at the tower end to separate the grounds completely - See "separately dervived ground" in the code. You'd have to take care to ensure the ground is truly isolated, but I think this is excessive. -forrest For longer On Wed, Apr 15, 2015 at 7:44 PM, Mark Radabaugh <m...@amplex.net> wrote: > For electrical service purposes the ground wire you have is fine. The > tower itself obviously needs to be well grounded. > > Where is your equipment? I'm assuming it's at the tower since you talk > about driving the battery charger. All of the equipment at the tower needs > to be bonded together with the tower ground and the electrical ground. > > A good 120V surge suppressor at the tower, grounded to the tower ground, > will help avoid damage from coming in over the power lines. > > You are not trying to protect equipment back at the breaker panel. The > ground wire size back to the panel is pretty irrelevant as long as it can > carry enough current to trip the breaker in a short circuit condition. > Other than that it doesn't serve much purpose. > > > Mark > > On Apr 15, 2015, at 3:41 PM, Paul McCall <pa...@pdmnet.net> wrote: > > In my continued disposition of acknowledging that I am not a electrical > grounding expert, I lay out this scenario for review, a new tower we just > built. > > > > We installed a new tower, approximately 200ft. from the service panel that > feeds it. We will be on our own breaker (kinda irrelevant here). > > > > In the past, we had run 10 gauge wire (x3) out to the tower with 110vac. > Voltage drop is relatively negligible, certainly within the bounds of > working properly to drive our 24v charger for the battery array. > > > > I was told, by a grounding “expert” that all my equipment electrical > grounds need to homerun to a bus bar that ride the ground back to the > service panel directly, that nothing else is acceptable. > > > > AND, and this is the big part… that I needed to seriously upgrade the > 200ft. ground wire only that rides back to the panel to something > significantly bigger. How much bigger I am not sure. > > > > So, I figured I would ask the crowd for an answer J > > > > Thanks! > > > > > > > > Paul McCall, Pres. > > PDMNet / Florida Broadband > > 658 Old Dixie Highway > > Vero Beach, FL 32962 > > 772-564-6800 office > > 772-473-0352 cell > > www.pdmnet.com > > pa...@pdmnet.net > > > > -- *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 forre...@imach.com | http://www.packetflux.com <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> <http://twitter.com/@packetflux>
