When two breakers are present within a box so that there are two ground wires going back to the panel for each circuit, do you/can you tie the grounds together if they are same gauge. As an example, I have two 15 amp breakers supplying a 4 gang box with a series of switches controlling several lights. Do I tie the grounds together or do they remain independent to their various light receptacles and fixtures. I take it that the neutrals should remain separate. Thanks
Electrical question for Larry
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Just a clarifying question (after modifying my answer 5 times LOL)
Are we talking about the bus bar on the service panel that the grounds screw into?
The part that has me confused is the begining sentence that says you have 2 breakers inside a box. How are you putting 2 circuit breakers into a gang box?
Are we talking about the bus bar on the service panel that the grounds screw into?
The part that has me confused is the begining sentence that says you have 2 breakers inside a box. How are you putting 2 circuit breakers into a gang box?
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I think he's talking about multi-gang box supplied with 2 feeders from the the main breaker panel.
| Originally posted by chirpie Just a clarifying question (after modifying my answer 5 times LOL) Are we talking about the bus bar on the service panel that the grounds screw into? |
If ken-ha is right about 2 feeds into the box then...
You can definitely tie the grounds together. You can also tie the nutrals together. You can share 1 neutral conductor with 2 circuits. An easy way to get two circuits to one location is to run 14-3 wire--this has ground, neutral (white), possitive (black), and possitive (red). The black and red conductors go to separate breakers, and the neutral and ground go to the grounding bar (btw, when I first started doing my electrical, I was confused that the ground and neutral actually both go to the same place).
However... I've seen many people here post that you should NOT use a shared neutral in a Home Theatre. I'm not sure why, but my guess is there's greater potential to intruduce noise in the line.
You can definitely tie the grounds together. You can also tie the nutrals together. You can share 1 neutral conductor with 2 circuits. An easy way to get two circuits to one location is to run 14-3 wire--this has ground, neutral (white), possitive (black), and possitive (red). The black and red conductors go to separate breakers, and the neutral and ground go to the grounding bar (btw, when I first started doing my electrical, I was confused that the ground and neutral actually both go to the same place).
However... I've seen many people here post that you should NOT use a shared neutral in a Home Theatre. I'm not sure why, but my guess is there's greater potential to intruduce noise in the line.
Your answer is a bit worrisome. The only time that you can share a neutral in the way that you describe is when they are on opposite phases ie breakers that are next to each other. In addition, a binding bar should be placed across the two breakers so that they can blow independently but must be turned off together. You can definitely not share a neutral on two breakers that are on the same phase. You would risk have 40 amps of current returning on a single 12 gauge wire which may lead to a fire. When the breakers are next to each other on opposite phases, each acts as the others neutral so that the only current coming back is the difference between the loads return current.
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This is the main reason why shared neutrals are not used in a Home Theatre. In order to reduce noise people like to place all of their equipment on the same phase. This is a definate no-no if you want to use a shared neutral.
RShlansky,
I guess my answer isn't WRONG, just incomplete. I've heard of using binding bars, but the electrician who wired my 6 month old house didn't use them. I found one instance of shared neutral so far, no idea how many I have yet.
I don't like sharing neutrals, but it is possible.
I guess my answer isn't WRONG, just incomplete. I've heard of using binding bars, but the electrician who wired my 6 month old house didn't use them. I found one instance of shared neutral so far, no idea how many I have yet.
I don't like sharing neutrals, but it is possible.
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You are right. I was sort of lumping them together, but two separate neutrals are different than a shared.
I did learn my lesson here. I'm not going to give advice on something unless I know all the details.
now back to building my wall...
| Originally posted by RShlansky We are getting a little off topic. We are not talking about sharing neutrals or grounds but binding them together. I was curious what the NEC says about this. One electrician I spoke to said that they should remain separate. |
I did learn my lesson here. I'm not going to give advice on something unless I know all the details.
now back to building my wall...
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Checkout my gallery or the link in my signature (that thread is all over the place, though).
I'm building 3 walls, I guess. One is stagger-studded, and will be at the end of the new hallway (that wall is up now). THe other two is a double-wall, wall. THat just doesn't sound right.
| Originally posted by chirpie What kind of wall? Drywall wall? Rock wall? Invisible opressions of the world wall? ;-) |
I'm building 3 walls, I guess. One is stagger-studded, and will be at the end of the new hallway (that wall is up now). THe other two is a double-wall, wall. THat just doesn't sound right.
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Okay, first of all, all grounds should be tied together in any box. The exception would be when using isolated-ground receptacles, which are a 100% waste in a non-metallic wiring system.
In other words, if you're using NM cable and plastic boxes, the ground wire is already isolated. In a metallic (i.e., metal conduit) system, the ground wire should be insulated and grounded only at the origination panel.
As for shared neutrals, the circuits must be on opposire phases. The two breakers need only be tied (i.e., a 2-pole breaker) if they're feeding a single equipment, or if they're feeding devices on a single mounting strap.
If two separate breakers feed two separate circuits sharing a neutral, when terminating the neutral at, say, a receptacle, the neutral must be spliced and pigtailed, not joined via the two silver screws on the receptacle.
This is because, since the two breakers are not joined, if someone turns off one circuit to replace a receptacle, the other circuit is still energizing the opened neutral through its loads, which is obviously dangerous.
Once leaving the panel (or a junction box with a 3-conductor cable feeding in and two separate 2-conductor cables leaving), two separate circuits must remain separate; in other words, never rejoin the two neutrals downstream.
If two separate 2-conductor cables are feeding several devices in one box, the neutrals should NOT be tied together. Treat them like two separate circuits. And never use one circuit's hot and another circuit's neutral.
In other words, if you're using NM cable and plastic boxes, the ground wire is already isolated. In a metallic (i.e., metal conduit) system, the ground wire should be insulated and grounded only at the origination panel.
As for shared neutrals, the circuits must be on opposire phases. The two breakers need only be tied (i.e., a 2-pole breaker) if they're feeding a single equipment, or if they're feeding devices on a single mounting strap.
If two separate breakers feed two separate circuits sharing a neutral, when terminating the neutral at, say, a receptacle, the neutral must be spliced and pigtailed, not joined via the two silver screws on the receptacle.
This is because, since the two breakers are not joined, if someone turns off one circuit to replace a receptacle, the other circuit is still energizing the opened neutral through its loads, which is obviously dangerous.
Once leaving the panel (or a junction box with a 3-conductor cable feeding in and two separate 2-conductor cables leaving), two separate circuits must remain separate; in other words, never rejoin the two neutrals downstream.
If two separate 2-conductor cables are feeding several devices in one box, the neutrals should NOT be tied together. Treat them like two separate circuits. And never use one circuit's hot and another circuit's neutral.
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