Ground Question

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  #1  
Old 04-17-05, 02:52 AM
hth
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Ground Question

I just replaced old 100A panel with a 200A panel. This old house didn't have ground. The electrician install a ground system: a rod driven into the ground (don't know how deep), a #4 copper in flex coil for protection tied one end to the rod and the other end to the underground water copper pipe. I also asked him to run 3 new 20A circuits terminated at a J box in the attic for future use. He put 3 hot wires, 1 neutral and 1 ground inside a metal pipe and ran from the panel (outside the house), entering the attic and from here I think he used flex coil instead of pipe and ended at a new j box.

1. For the receptacles in my office which have no ground, can I add a ground wire connecting to either the ground wire at the new J box or the #4 wire he used for ground system? Technically does it serve the grounding purpose if the code doesn't allow?

2. The wiring of 3 new circuits above, did he do correctly per code? He did very well and neat job when he replaced the panel with the inspector behind but I am not sure how he did the new circuits since this isn't inspected .

Thx.
 
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  #2  
Old 04-17-05, 05:11 PM
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One neutral cannot serve three hots in typical residential power systems (unless you have three-phase power, which is extremely unlikely). Are you sure about what you reported?

You mentioned a wire between the grounding rod and the water pipe. Is there also a wire from the panel to either of those?
 
  #3  
Old 04-17-05, 08:42 PM
hth
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One neutral cannot serve three hots in typical residential power systems (unless you have three-phase power, which is extremely unlikely). Are you sure about what you reported?
I asked him how he would do then he explained that to me. I asked him why not 3 separate white wires for 3 circuits then he said it isn't needed. He even told me 5 wires total. Damn it. Must it be 3 blacks, 3 whites and one ground? I am not electrician but would have known that this isn't working. I must go to the attic tomorrow and double check.
I hope he told me worng thing but did right thing. Otherwise it woud be a mess.

You mentioned a wire between the grounding rod and the water pipe. Is there also a wire from the panel to either of those?
Yes. The rod is right below the panel. A wire from panel to the rod and another wire from the rod goes up and into the attic toward the other end of the house then exist the attic, go down and tied into the water pipe.
 
  #4  
Old 04-17-05, 09:13 PM
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Have you actually looked to see what wires are there? Three hots and three neutrals is always okay. Three hots and two neutrals is often okay. Three hots and one neutral is never okay. Check it out. Be sure.

Running an equipment grounding wire along with the circuit conductors is always preferred. It helps trip the breaker faster. If this is impractical, then you can run the grounding wire separately.
 
  #5  
Old 04-17-05, 09:21 PM
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Looks like the electrician properly grounded everything by bonding everything together. John just wanted to make sure everything was bonded together, including the panel since it is required. As for the 3 hots and only one neutral setup, John is right, you can only have that in a 3-phase setup. Since houses generally are only single phase, you can only share 2 hots on a neutral, providing each hot is from a different phase in the panel. Phases probably might be a little confusing to you but thats not really important unless you really want to understand them. The only thing that I can come up with for why he ran what he ran is maybe he has it setup for one 120v power feed and one 240v power feed, meaning the 240v wouldn't need a neutral. However, he still should have ran at least one more neutral, preferably 2 more, because maybe you will never want 240v. Go back up and double check like you mentioned and find out for sure. If your finding are what they were before, call back the electrician and ask him to explain to you why he did it that way. And if he doesn't give you a good answer or whatnot, demand that he come back and do it correctly for you. Hopefully you just miscounted your wires. Hard for me to believe an electrician would wire something this way, unless he is a commercial electrician or came from commercial and got a little confused there and was thinking 3-phase instead of single-phase.

Best of luck, let us know how it comes out.

Paul
 
  #6  
Old 04-17-05, 11:44 PM
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Could he have installed 3 hot, 2 neutral, and plan on using the conduit for the equipment grounding?
 
  #7  
Old 04-18-05, 01:13 AM
hth
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Unhappy :

I didn't check out the j box myself when he finished the job. I first asked him I wanted this and this and would he run 3 new circuits. He even had it in a draw for me that 3 hots, 1 neutral and 1 ground. I was confused but was exhauted remodeling my house so I didn't think about it later. I have a little knowledge with the electrical things but I just didn't think about the impossiblity of what he said. I know basic about the phase but for the Cutler Hammer 200A panel (will look for the model # later) it has 1 left side for the meter sealed and right side with breakers. The 3 new circuits he ran for me they were from 3 new single pole breakers installed in the last 3 bottom slots in the panel. So I can't tell if any 2 are from different phase without looking further into the diagram, etc. Anyway I will look up tomorrow and update later.

Damn. I think I will call him first thing tomorrow. He holds a C10, C20, and B license. If he wired the circuits incorrectly as he told me, is the worst thing NO current flow in the other 2 circuits? Whatever I find out tomorrow, he is already out of state wiring a salon and won't be back in 2 weeks.
 

Last edited by hth; 04-18-05 at 01:50 AM.
  #8  
Old 04-18-05, 05:31 AM
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"If he wired the circuits incorrectly as he told me, is the worst thing NO current flow in the other 2 circuits?"

No. The worst thing is that you create a fire hazard by overloading the neutral, burn down your house and kill someone in the process.

It is imperative that you determine exactly how this new wiring is run so that you can either have it redone properly or use it as it it is safely (which may mean as only two circuits).
 
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Old 04-18-05, 07:14 AM
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From a theoretical perspective (code aside) if the neutral were oversized to carry the current, would it be safe to run 3 circuits using one common neutral?
 
  #10  
Old 04-18-05, 07:29 AM
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We can speculate a bunch of "what ifs" until the cows come home, but it's all fairly useless until he actually looks to see what he has. There are a thousand ways it might be wrong and a hundred ways it might be right. We can't discuss them all.

But yes, in theory an oversized neutral could make this safe. I think it's very unlikely, however, that this is the case here.
 
  #11  
Old 04-18-05, 07:35 PM
hth
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Update

Here is what I found out. I didn't call the electrician first since I wanted to check the circuits, discuss here and talk to him with firm voice. There are 3 reds, 2 whites and 1 ground. It was NOT as what he drew on back of the contract I still have.

So is it safe now? John, you said "Three hots and two neutrals is often okay". Is there a condition to make it OK? Do the 2 circuits sharing 1 neutral must be from different phase? How to find out if 2 hot wires are on same or different phase? The panel is Cutler-Hammer MBE2040Bxxxx, looks like this one http://www.acehardwareoutlet.com/htm...ist352-5_4.htm

Thanks.
 

Last edited by hth; 04-18-05 at 07:46 PM. Reason: addition
  #12  
Old 04-18-05, 09:11 PM
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The setup you have can be made safe for three circuits, and probably already is. Use two reds from different halves of the incoming service and one of the neutrals. as a multi wire circuit (the voltage between the two reds must be 240 volts). Use the other red and the other neutral as a plain 120 volt circuit.
 
  #13  
Old 04-18-05, 09:16 PM
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Hth,

That clarifies everything now. 2 Neutrals are sufficient to handle all three hots. In answer to your question about phases, go open up your panel... You should see every breaker numbered... most likely 1-42, however could be less. odds on the left, evens on the right... Both 1 and 2 are on A phase, 3 and 4 on B phase, 5 and 6 on A phase and so on... If you look in your panel, you will also probably notice a few 2 pole breakers, these look like 2 breakes molded together with one long switch. These breakers supply power to something needing 240v. That breaker is actually on both the A and B phase... remember how I mentioned the panel goes A-B-A-B-A and so on from the top of the panel down to the bottom? If you forget, just look for a 2 pole breaker to remind you that the phases go up and down, not side to side. So basically 2 red wires are on either phase A or B and the third red wire is on the other phase. So.... in the future when you decide to use those circuits for something.... just remember A & B can share a neutral, but neither A & A or B & B can share a neutral, because it can overload the neutral and start a fire like racraft said.

Hopefully this made a little sense, and if it doesn't, don't feel bad. When I started in electrical, I started in 3 phase and it took me a while to understand what phases can and cannot share neutrals, and really grasp why. It is all in the process of learning,

Anyways, Best of luck and rest ashured that it was setup properly.

Paul
 
  #14  
Old 04-18-05, 09:23 PM
hth
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:-)

I got it now. Thanks gentlemen.
 
  #15  
Old 04-19-05, 05:24 AM
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"Both 1 and 2 are on A phase, 3 and 4 on B phase, 5 and 6 on A phase and so on... "

The above may not be true (it isn't with my panel). It all depends on how your panel is numbered. Be less concerned about numbers and more concerned about breaker positions. Just make sure that the two breakers you pair with the single neutral allow for 240 volts between them.
 
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