grounded conductor

[eager2learn]

when you have two ungrounded conductors on the same phase can you share the same grounded counductor with the exception of wiring a g.f.i. - also i heard that in the new code the grounded conductor cannot be white by itself anymore, rather it must have a gray stripe do to the fact of discoloration. i looked it up and could not find it anywhere

 

[celtic]

when you have two ungrounded conductors on the same phase can you share the same grounded counductor with the exception of wiring a g.f.i. -

Sure..it's a Multi-Wire Branch Circuit [MWBC]
Check 210.4

...and there are ways to wire GFCI devices using MWBC.

also i heard that in the new code the grounded conductor cannot be white by itself anymore, rather it must have a gray stripe do to the fact of discoloration. i looked it up and could not find it anywhere

I heard the world was flat...I looked and couldn't find that either :smile:

The grounded conductor does NOT need a gray stripe.

 

[Dennis Alwon]

when you have two ungrounded conductors on the same phase can you share the same grounded counductor with the exception of wiring a g.f.i. - also i heard that in the new code the grounded conductor cannot be white by itself anymore, rather it must have a gray stripe do to the fact of discoloration. i looked it up and could not find it anywhere

This will be debated technically you can use a common neutral for 2 wires on the same phase but you will have to size the neutral accordingly. I would think if you share a neutral then you should have to use a DP breaker on that circuit as 210.4(B) requires and that would no be possible. Unforunately 210.4 does not address this issue nor does the NEC

The coloration thing is bogus. It does not exist.

 

[Dennis Alwon]

Sure..it's a Multi-Wire Branch Circuit [MWBC]
Check 210.4

I don't believe it is a MWBC if the ungrounded conductors are on the same phase.

 

[jeremysterling]

A smart-aleck answer would be yes, if the ungrounded conductors were 1/0 or larger and parallel. However, I think you are saying the ungrounded conductors are separate branch circuits on the same phase, so the answer would be no if the grounded conductor had the same ampacity as one of the ungrounded conductors. I'm not sure where the GFCI plays into all this.

As far as the gray stripe on the grounded conductor, and I do not have the code in front of me, but I'm pretty sure white is the go to "color" and will be for some time to come.

 

[raider1]

Sure..it's a Multi-Wire Branch Circuit [MWBC]
Check 210.4

Actually if the ungrounded conductors are on the same phase you would not have a voltage between them and this would not be a multiwire branch circuit.

Chris

 

[celtic]

I don't believe it is a MWBC if the ungrounded conductors are on the same phase.

I just caught the same phase portion....but missed the time restraint to edit my post.

That changes things a bit, for sure :wink:

 

[jeremysterling]

This will be debated technically you can use a common neutral for 2 wires on the same phase but you will have to size the neutral accordingly.

I agree, but I didn't explain as well as you did.

 

[don_resqcapt19]

The code specifically permits the use of a "common" grounded conductor with multiple ungrounded conductors of the same phase in two locations in the code with the use of the words "shall be permitted". It is the code panels position, one that I don't agree with" that the words "shall be permitted" act to prohibit all other uses of a common neutral. The two code sections that specifically permit this are 215.4(A) and 225.7(B).

 

[Buck Parrish]

when you have two ungrounded conductors on the same phase can you share the same grounded counductor with the exception of wiring a g.f.i. - also i heard that in the new code the grounded conductor cannot be white by itself anymore, rather it must have a gray stripe do to the fact of discoloration. i looked it up and could not find it anywhere

If you have two neutrals in the same race way. One should be identified as to which hot(s) it is to go with.
May be that's what you are thinking of.

 

[eager2learn]

here's the situation - i'm currently working at a airport where major renovation is being done in a courtyard area. my main panel is located approximately 450' away from my last light fixture. 3/4 p.v.c. conduit was installed with the assumption that #10 thhn would be suffiecient for voltage drop. this isn't the case - after voltage drop calculation i found that # 6 thhn is required. the total amperage of the circuit is 7.8 amps and the voltage is 120. now with all that being said, the flatwork in the courtyard area has been poured to complicate things. this is why i want to know if i can share the grounded conductors because i can only fit 4 # 6 thhn in 3/4 p.v.c. and i have 5 circuits in this location with 3 - 3/4 spares and 1 - 1 in. spare. this is going to be a hard pull

 

[nolabama]

i just completed a 450' underground pull with # 6 instead of a smaller wire - actuall voltage read at outlets was the same as was recorded at the lugs - did not loose one volt - used 2 inch although

 

[don_resqcapt19]

i just completed a 450' underground pull with # 6 instead of a smaller wire - actuall voltage read at outlets was the same as was recorded at the lugs - did not loose one volt - used 2 inch although

If there is a load, there is a voltage drop. It may not be much with a small load, but there is some.

 

[Dennis Alwon]

i just completed a 450' underground pull with # 6 instead of a smaller wire - actuall voltage read at outlets was the same as was recorded at the lugs - did not loose one volt - used 2 inch although

Try putting a load on it and then measure the voltage.

 

[nolabama]

oh....humph, i like learning - i just hate feeling like a dumb while i learn

 

[eager2learn]

my problem is that the 3/4 in. p.v.c. is already installed and the concrete is poured. i'm trying to find a way to use the existing p.v.c. so we don't have to saw cut the concrete.

 

[infinity]

my problem is that the 3/4 in. p.v.c. is already installed and the concrete is poured. I'm trying to find a way to use the existing p.v.c. so we don't have to saw cut the concrete.

Might not be feasible but higher voltage fixtures may help.

 

[Buck Parrish]

I want to know if i can share the grounded conductors because i can only fit 4 # 6 thhn in 3/4 p.v.c. and i have 5 circuits in this location with 3 - 3/4 spares and 1 - 1 in. spare. this is going to be a hard pull

You can share neutrals, Three hot's to one neutral for a three phase panel. Two for single phase.

 

[1793]

If I understand correctly you want to use one grounded conductor for two ungrounded on the same "phase".

This is not a MWBC but you can share the same grounded conductor as long as the grounded conductor can handle the combined load of the two or so ungrounded circuits. I would install a handle tie however if sharing the same grounded conductor.

Two 20a 120v circuits on the same phase would need a grounded conductor that will handle 40a.

 

[wirenut1980]

I don't think it is possible to protect the neutral from being overloaded using 4conductors.

I would install a buck/boost transformer somewhere along the circuit.