What size of cable suitable_ 40 Amps, 250'/ 200'?
Asked Dec 8, 2007, 05:00 PM
I would like some information on wire AWG and grounding requirements with regards to generators. I set up remotely located mineral exploration camps in BC Canada- I am not an electrician... but would like to have some general information, and have an interest in electrical.
Our camps are generally 12-20 man, we commonly use a 10.7 kW (10.7kVA) prime rated diesel generator. Single phase, 240 V, ground and neutral are bonded. The generator has a 50 amp square D series 3 main breaker that is then wired to a Hubbell 50 amp (3 pole 4 wire) receptacle mounted to the generator panel. From the generator receptacle a 200 foot "extension cord" connects the generator to the main electrical distribution panel in camp- power is then distributed from that main panel- 120 volt circuits. The camp is setup and taken down a number of times in one field season, normally the projects are approx. 6-8 weeks in length... so in other words everything needs to come apart easily, wound up, and reused for the next deployment- and is the reason for the 50 amp receptacles/ plugs and flexible rubber extension cord set up.
Presently the generator “extension cord” is made up of a 200 foot piece of 8/4 Carol SJ00W, weather resistant ,4 conductor rubber insulated copper cable. From everything that I have read- 8 AWG is too small given the length and 40 amp draw.
I would like to know:
1. What AWG of cable should be used for an extension cable of 200' long? 250' long? Voltage is 240V; total maximum draw would be 40 amps, but probably much less at any given time. I am concerned about voltage drop, and amperage capabilities of the cable.
2. How should grounding be done at the generators? At the panels? And at any sub panels?
….Presently the generator is grounded via a grounding plate that is connected to the Generator chassis using a bare #4 copper wire (so the entire unit is grounded- the generator is wired so that neutral is bonded to ground). The ground is then continued through the generator receptacle/ plug to one of the conductors of Carol 8/4 cable. (so in other words at the receptacle on the generator there is a ground, a neutral, and two others). At the main electrical distribution panel at the for end of the extension cable- neutral and ground are bonded together, there is another grounding plate that is connected to the panel with a bare #4 copper wire…. If I was to wire a sub panel would I continue to bond neutral and ground at the panel, would I need a bounding plate?
Thank you for any information you have for me.