Electrical Circuit Question

[Steve Roxberg]

I have an interesting situation and want to do this to code and as safely as possible.

I have two separate 20 amp breakers (not bonded together) in my main panel (ground and neutral bars in panel are bonded together being a main).

Both circuits leave the main panel in EMT which serves as the ground so two hot wires, and two white wires.

The circuits have to transition through some tight bends that EMT would not be best for so I have the wires running through a short 2 foot section of flexible conduit in a protected area.

I carried a ground wire from the end of the EMT that is connected to the main panel and connected it back into the new metal junction box.

I'm assuming that the ground is correct since it is shared.

I plan to keep the white (Neutral) wires separate all the way to the outlets but was wondering since the ground and neutral are bonded at the panel if it made a difference.

I've always kept neutral wires and hots paired together through a complete circuit.

Any issues with what I'm trying to do?j

Why am I confused?

[Jim Dwight]

My quick google search indicates that both rigid and flexible metallic conduit is an acceptable ground conductor according to the NEC. That does not preclude local requirements for a ground conductor, however. I do not remember seeing any commercially available romex without a ground, however. If you've already paid for it, why not hook it up?

Regardless of what happens in the breaker box, the neutral is not the ground in the circuit. You could omit the ground and be safe and possibly code compliant (depending on local requirements) but you cannot use the neutral as a ground and comply with anything.

[Bob Cooper]

Is your question whether or not you need to keep the neutrals separate throughout the circuit?

[Dan Friedrichs]

I don't understand your question, either...

You can use either EMT or metallic flex as the ground, and do not need to pull a separate ground wire. As long as there is a continuous conductive path through the rigid+flex conduit, you're fine. Not sure what this ground wire you pulled is for.

Are you asking if there needs to be a separate neutral wire for each outlet? Yes. If you "shared" the neutral wire between two 20A loads, there would be the potential for 40A flowing on the neutral (which it is not rated for, and which would cause it to melt, and neither of the breakers would stop it, since they each only carry 20A). So, yes, carry a separate neutral to each outlet.

I think you're getting confused because you're conflating the purposes of the neutral and ground conductors. Forget about the ground for a minute: you need a hot and a neutral to each outlet. "Wire" those connections in your mind - nothing hard about this, just two separate wires to each outlet. The ground is separate, and provided by either the conduit or another wire.

[Jason Roehl]

Neutral and ground ("Grounded" and "grounding" are the "proper" terms) and must only be bonded together at the main panel. Everywhere else they need to remain separate.

As for two hots and two neutrals, if those breakers are adjacent, and can be replaced by a tandem breaker (typically used for 240V), then you could do away with one of the neutrals. The reason being that two adjacent slots in a panel are 180º out of phase with each other, so their currents cancel each other on the neutral. So if both legs are drawing 20A, on one of the legs the current is incoming, and the other it's outgoing (and this reverses 60 times per second in the U.S.). If these two circuits share a neutral, there would be no current on it.

[Bob Cooper]

Not to hijack this thread but I do have a theoretical question. If I had two lights on two separate circuits but the switches for those light shared a single box would it be a code violation to join the neutrals together or do I need to keep them separated.

[Rollie Meyers]

Not to hijack this thread but I do have a theoretical question. If I had two lights on two separate circuits but the switches for those light shared a single box would it be a code violation to join the neutrals together or do I need to keep them separated.

Keep them separate unlike grounding conductors which must be bonded together, interconnecting neutrals can cause issues.

[Paul F Franklin]

Absolutely keep them separate. Let's say you want to work on a circuit where upstream somewhere two neutrals from two circuits were tied together. Now you are working on one of the circuits. You shut off that circuit, and your voltmeter verifies that no wires are live. You disconnect the neutral wire and get a good shock! Why? Because you only turned off one circuit. The other circuit was still on and current was flowing through the neutral wire. Because the neutral is grounded at the panel, when you test the neutral it will measure zero volts (or very close). But if you disconnect it, it jumps up to 120 volts because it is tied to the second circuit, which is live.

I have had this happen to me more than once when neutrals were inadvertently cross connected. So I've learned to treat neutrals as live until they are disconnected and both ends test dead.

This can also happen with multiwire branch circuits where a neutral is shared on purpose and correctly. Such circuits require a two pole handle tied breaker so both circuits are controlled simultaneously.

[Bill Space]

Yes, as Paul said, absolutely keep the neutral wires (today more properly named the "grounded conductor") separated.

With regard to a white wire becoming hot if disconnected, this will happen even if there is no cross connection of the grounded conductors between circuits. For example, if the white wire is removed from the common bus in the service entrance panel, then if any switch in that circuit is closed (or any device plugged into a receptacle), then the white wire for that circuit will become energized and be a shock hazard.