Neutrals

[skorper]

Sorry for suh a rudimentary question, but here it goes-
How many, and or size, neutrals are needed to supply multiple circuits?
(120v 20A 12 AWG wire, breakers generally are sized to supply up to 13 outlets-non residential)
Instead of running 1 12AWG neutral wire per circuit, how many circuits/outlets can I wire using 1 12 AWG neutral?
OR can I increase the neutral gauge to supply multiple circuits?

Thank you.

Steve

 

[pete m.]

As long as the neutral is shared among opposing phases you could have up to three ungrounded conductors sharing one neutral (on a three phase system of course).

Just make sure and check out 210.4(B)

Pete

 

[infinity]

If you're covered under Article 225 you can run on big neutral sized for all of the connected neutral current. If you're not under Article 225 then you cannot run one oversized neutral for circuits on the same phase. What are the specifics of your installation, i.e.-voltage, phases etc.?

 

[Alwayslearningelec]

As long as the neutral is shared among opposing phases you could have up to three ungrounded conductors sharing one neutral (on a three phase system of course).

Just make sure and check out 210.4(B)

Pete

That is "disconnecting means"

 

[Dennis Alwon]

That is "disconnecting means"

If you had one neutral and a bunch of circuits on opposite phases how would you simultaneously disconnect all the cir. 2011 has made it clear that this is not allowed.

 

[skorper]

I must not be explaining this correctly.
Let me try again-
120 Volts Alternating Current,
Single Phase,
20 Ampere Circuit Breaker,
12 American Wire Gauge Wire.

So far so good?

Am I correct to say that the NEC allows me to connect up to 13 outlets per circuit?
(One Black Wire, one White Wire, and one Green/ground Wire.)

Instead of running a separate White Wire (neutral) for EACH circuit, HOW MANY outlets/load CAN I run off this wire?

MC cable can run multiple circuits with just ONE white wire. (i.e.-Black, Red, White, and Green).

PS: This is INSIDE for a commercial building.

Steve

 

[roger]

I must not be explaining this correctly.
Let me try again-
120 Volts Alternating Current,
Single Phase,
20 Ampere Circuit Breaker,
12 American Wire Gauge Wire.

So far so good?

Am I correct to say that the NEC allows me to connect up to 13 outlets per circuit?
(One Black Wire, one White Wire, and one Green/ground Wire.)

Instead of running a separate White Wire (neutral) for EACH circuit, HOW MANY outlets/load CAN I run off this wire?

MC cable can run multiple circuits with just ONE white wire. (i.e.-Black, Red, White, and Green).

PS: This is INSIDE for a commercial building.

Steve

You are only describing a single circuit and if you are talking about a residential installation you can connect as many receptacle outlets as you want on this circuit.

Roger

 

[infinity]

I must not be explaining this correctly.
Let me try again-
120 Volts Alternating Current,
Single Phase,
20 Ampere Circuit Breaker,
12 American Wire Gauge Wire.

So far so good?

Am I correct to say that the NEC allows me to connect up to 13 outlets per circuit?
(One Black Wire, one White Wire, and one Green/ground Wire.)

Instead of running a separate White Wire (neutral) for EACH circuit, HOW MANY outlets/load CAN I run off this wire?

MC cable can run multiple circuits with just ONE white wire. (i.e.-Black, Red, White, and Green).

PS: This is INSIDE for a commercial building.

Steve

You can put 13 receptacles on a 20 amp circuit in a commercial building (wait for some contradictory comments). If the system is 208Y/120 you can run three 20 amp circuits with one common neutral. That would be a MWBC or multi-wire branch circuit.

 

[zbang]

Am I correct to say that the NEC allows me to connect up to 13 outlets per circuit?

Instead of running a separate White Wire (neutral) for EACH circuit, HOW MANY outlets/load CAN I run off this wire?

I think you're somewhat mixing outlet and circuit. In normal practice, if you have a single 12g white wire (a neutral), you can share it among as many 20a single phase circuits as you have different phases (check out "multi-wire branch circuit"). 'course, that's usually only 2 or 3.

All that said, I generally only see MWBCs where the outlets are fairly close together, and usually they are only 2-3 duplex on a circuit. Other installations may differ.

How many outlets you connect to each circuit is irrelevant to sharing of the neutral/grounded conductor. Search the forum and you'll find lots of discussion how many outlets per circuit.

 

[maghazadeh]

As long as the neutral is shared among opposing phases you could have up to three ungrounded conductors sharing one neutral (on a three phase system of course).
Just make sure and check out 210.4(B)

Pete

OR, up to 6 opposing circuits sharing one neutral (on a six phase system), the bad part is that neutrals are not used on a six phase system.

 

[skorper]

I understand the difference between an outlet and a circuit.
So if I have a 208 three phase panel, 20A breakers, I can have THREE circuits EACH having a maximum of 13 outlets using MC 12/4, as long as each circuit is on its own phase.

Is THIS correct?

Steve

 

[jumper]

I understand the difference between an outlet and a circuit.
So if I have a 208 three phase panel, 20A breakers, I can have THREE circuits EACH having a maximum of 13 outlets using MC 12/4, as long as each circuit is on its own phase.

Is THIS correct?

Steve

Yes. It is really just one circuit. MWBC.

 

[skorper]

Just like pulling teeth.

Thank you!

The code isn't always easy to understand.

Steve

 

[maghazadeh]

I understand the difference between an outlet and a circuit.
So if I have a 208 three phase panel, 20A breakers, I can have THREE circuits EACH having a maximum of 13 outlets using MC 12/4, as long as each circuit is on its own phase.

Is THIS correct?

Steve

Let not forget that OP was about sharing neutral. I don't know what you mean by "as long as each circuit is on its own phase.", but your statement above is correct if the 12/4 MC is connected to 3 different phases. (Phases A, ,B, and C).

 

[jumper]

Just like pulling teeth.

Thank you!

The code isn't always easy to understand.

Steve

Post #2 and #8 answered you already.

 

[Fulthrotl]

I understand the difference between an outlet and a circuit.
So if I have a 208 three phase panel, 20A breakers, I can have THREE circuits EACH having a maximum of 13 outlets using MC 12/4, as long as each circuit is on its own phase.

Is THIS correct?

Steve

yes.

 

[cdslotz]

I understand the difference between an outlet and a circuit.
So if I have a 208 three phase panel, 20A breakers, I can have THREE circuits EACH having a maximum of 13 outlets using MC 12/4, as long as each circuit is on its own phase.

Is THIS correct?

Steve

Provided cirtain outlets are not dedicated for a special use.
Plus you can only load that circuit to 80% (1920VA)

 

[skorper]

The thing is, I see so many multiple circuits on the same phase sharing the common neutral.

 

[zbang]

The thing is, I see so many multiple circuits on the same phase sharing the common neutral.

That may be, but they're probably all violations, then. If you have a 15a load on one breaker, a 15a load on another breaker, and they're both on the same phase, the return current will be 30a. That's the math. Unless that shared conductor is rated for 30a, you have an overload problem. Even if it is, I don't know of any place in the code that would allow it.

If you search the forums for "spot the violation" messages, you'll see lots of things people do that aren't to code.

 

[blargh]

I ran into that problem exactly when rewiring a house. They had apparently tried to run a "MWBC" to the kitchen, but landed both hot legs on the two sides of the same half-width 20 A breaker. Since those are both on the same phase, the common 12 AWG neutral could have seen up to 40 A returning.

Even worse, they had tried to split a duplex receptacle between the two breakers, but actually forgot to break off the tab on the receptacle. When they were on the same phase, it was no problem (except the above), but when I moved it over to a proper MWBC in the new panel it was a 240V dead short!