Hi, I just bought an electrical work book that describes how to wire a circuit breaker panel. They explain that there is a ground wire strip and a neutral wire strip. However, when I looked at my panel that a licensed electrician just installed I realized that both strips have both neutrals and ground wires attached. The book also says that in a main panel the two strips are bridged so I guess it doesn't matter which strip the grounds and neutrals are connected to. Am I correct? If I add a new breaker can I safely connect the ground and neutral to either strip? Thank you, Stephan.
Yes. In the panel that contains the main disconnect, the ground and neutral are connected together. This usually means they are bridged in the circuit breaker panel (but not in a subpanel.)
If you have enough spaces in each strip, I suggest putting the neutral wire in the neutral strip and the ground wire in the ground bus and you won't have to know if they are interconnected. (The ground strip has the big bare copper wire going to it, and the neutral strip has a big insulated wire going to it that may be copper or aluminum.)
This is true. If you were looking inside a -sub-panel rather than your main panel, they would be discreet, but as you're about to find out...
Yes you are.
Yes. It's common practice (at the main panel only, where ground and neurtal are physically connected together) to put the stripped neutral wire and the bare ground wire in the same hole, and tighten down the set screw. This is, of course, limited by wire size, but most holes will accept 2*12 guage or 2*14 guage wires.
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I've never seen panels where the terminal strips were listed for 2 wires in 1 hole, not that I've looked at that many. (some breakers are listed for 2 wires under 1 screw.) You wouldn't want both ground and neutral for the same circuit under one screw anyway, because if it somehow came loose you would lose your equipment ground the at same time as you lost the neutral.
Just on the outside chance that you're not here solely to argue with me (a sock puppet to one of my Code-a-holic buddies???) I'll just say that:
1) If that does indeed happen, and both wires somehow manage to lose contact with the bus at the same time, the circuit will not work, and somebody will no doubt try and find out why.
{OF COURSE THIS WOULD also HAPPEN IF YOUR SOLO NEUTRAL WIRE COMES OUT OF IT'S HOLE!) Best case scenario: they will just dangle in midair until found, maybe bounce off of the box sides or cover panel. "Worst" case scenario, they bounce and hit the hot side of a breaker, which would be a dead short to ground and trip that breaker. Again, a clue hat something is amiss in the load center.
{OF COURSE THIS COULD also HAPPEN IF YOUR SOLO NEUTRAL WIRE COMES OUT OF IT'S HOLE!)
2) When you wire a conductor into a service panel, there should be little or no physical force attempting to pull a wire from its resting place. IOW, you route your wire, bend it and form it so that it sits right where it needs to be, and then you tighten it under the screw. That holds true whether it's going into the ground/neutral bus bar(s) or onto the end of a breaker. You also torque down the screws nice and tight. So, in summation, while it is indeed -possible- (remember, just about ANYTHING is "possible") it's about 99.99999999% certain (assuming that the box is wired with good workmanship practices) that your scenario will ever happen.
So go on, tell me about some magical force pulling these properly routed and formed wires *out* of the terminal strip (is this an earthquake we're having, by any chance? ) and somehow, someway twisting and bending themselves while in midair so they can walk up and hit one of the unfused hot wires attached directly to the meter base.
{OF COURSE THIS COULD also HAPPEN IF YOUR SOLO NEUTRAL WIRE COMES OUT OF IT'S HOLE!)
They don't have to come out of the hole to cause a problem, just loose so there's a bad connection -- probably when someone is messing around it the panel, or if they weren't tightened down properly when installed. I didn't personally tighten the screw, so I don't know if it was good and tight or not. It's an unnecessary risk, and I'm pretty sure it would be faulted by the building inspector if he ever saw it. (if my solo neutral wire comes out of its hole, the equipment ground still has a good connection and shunts any leakage back to the panel and drasticly reduces the shock hazard.)
So don't put the ground and neutral for the same circuit in the same hole. If you want to put 2 grounds or 2 neutrals in one hole because you're running out of spaces, be my guest (but I'm pretty sure an inspector would have a hissy fit about that too unless the panel has a sticker from the manufacturer that says it's OK)
Which could also happen with your single neutral wire in its own hole.
Don't assume faulty workmanship. If you do, you could make an argument against just about any wiring practice.
Don't assume faulty workmanship. If you do, you could make an argument against just about any wiring practice.
And without a neutral, your circuit is dead to the user. How long do you propose they will let it sit that way unrepaired? Obviously long enough (in your opinion) for some miraculously simuultaneous problem to cause a ground fault.
Why? Because you believe every possible worst case scenario is going to happen at the same time? Well yeah, there's that earthquake thing, I guess. Maybe my 2 wires will be violently yanked from their common hole before the ground opens up and swallows your home, or that giant oak tree falls and cuts it into two pieces. But then again, maybe not.
Sorry to be such a smartass about this, really I am. But guys like you will argue against cold, hard reality until you're blue in the face. Don't know how to break it to you, but a whole lot of people wire their homes like this, the screws don't magically work themselves loose and wires don't animate and start hopping around in load centers. A hack that doesn't tighten a set screw properly is an accident waiting to happen anywhere, it has nothing to do with how many wires are under that screw.
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