Not an electrician, but i have a question. My son-in-law bought a new mobile home. The service has four wires. Two wires are tied on the same terminal at both the indoor distribution box and at the sevive disconnect. Other than to sell more wire, what is this for?
I've seen this on three homes. However, I only clecked my son-in-laws system closely. The trailer ground is tied to the neutral in the indoor distribution box. Therefore, I don't see it's purpose. This was connected by a licensed electrician, out of S>A> When I ask him about it, I was told the fourth wire made no difference and was there only for insurance purposes.
The neutral should be bonded to the ground outside in the main panel/disconnect. Four wires should be run from that main to the panel inside the trailer. There should be no connection between ANY of the grounds (green or bare wires) and the neutrals (white wires) inside the trailer panel. The ground wire ran with the feeder should be tied to the trailer grounds as well as the panel box itself. The main neutral should connect to the trailer panel neutral bar containing the circuit neutrals. This neutral bar SHOULD NOT be bonded to the panel enclosure and thus the ground bar.
Remember, just because an electrician claims to be licensed, that does not necessarily mean that he knows what he is doing (I have worked with a number of very code ignorant licensed/certified electricians!). I would suggest having a more knowledgeable professional remedy the problem and them bill the initial electrician for his mistake. This serves two purposes. First of all, this "electrician" needs to be made responsible for the addition costs incurred by the homeowner. Secondly, the electrician needs to learn from his mistake and begin wiring future trailers correctly. All four wired subpanels need to be wired this way so this electrician is most likely miswiring all other such systems. This needs to be stopped (I sure hope this guy does not have his hands in any farm wiring! Not four wiring or four-wiring incorrect are a couple of the big issues regarding that ugly subject known as stray-voltage).
Went back over there and took another look. At the rear of the house, there is a #6 bare wire connecting the two halves. Then a take off that disappears in the bottom. Inside, what I believe to be the same wire, it is tied to the ground bar. There are two bars, one each side, connected by another bar. Which, to me, means it is all tied together. This part is factory installed.
cecil, without seeing this in person or having lots of details and pictures, it's really hard to say if this is right or wrong. The bar that connects the equipment ground bar and the neutral bar, is it metal or plastic? If you're unsure about this installation, and you must be or you wouldn't have posted a question about it, please call a licensed electrian for a second opinion.
Life is good. Went back to the small town my son-in-law lives in. Called the city inspector out. Pulled the covers off and let him look. After a long blank stare, his reply. "I am a plumber, I have no idea what I am looking at." He is the only city inspector in town. Called the manufacturing company, they are sending a man down Thursday.