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Old Coot
08-14-2008, 02:14 PM
Bringing electricity from main panel to sub-panel @ shed 20 feet away. I'm using #12 THHN conductors in 3/4" conduit with two conductors providing 240V to a dedicated air conditioner outlet and two conductors for two separate 120V, 20A outlet circuits for hand tools, etc. My question is do I need to run two separate neutral conductors for those 120V circuits or is one sufficient? Thanks in advance for your help.

Bob NH
08-14-2008, 04:00 PM
It isn't clear that you are installing a subpanel.

It sounds like you are running complete circuits from the main panel.

If you are installing a subpanel you run one circuit from main to the subpanel. If you have a subpanel you need one neutral + two hot + ground.

If the calculated load doesn't exceed 30 Amps you can run a #10 circuit to the subpanel, and then run the 20 Amp circuits to the A/C and the other outlets. If you want more you can run #8 to the subpanel and put it on a 50 Amp breaker in the main.

You don't need a neutral for the 240 Volt circuit.

You can run the two 20 Amp circuits as a multiwire branch circuit which consists of two ungrounded (hot) conductors and one neutral. When you get to the point where the circuits diverge you will connect both of the circuits to the one neutral.

Alectrician
08-14-2008, 04:01 PM
One will do it but @ 20 feet, I'd spend the extra 2 bucks and run separate neutrals just to avoid any issuers with the multi wire branch circuit.

If you use one neutral and somehow, thru a loose connection loose the neutral going to the panel, you will end up with 240V at your 120V outlets (if there is a load on one circuit). Separate neutrals will eliminate that possibility.

jwelectric
08-14-2008, 04:26 PM
It never ceases to amaze me the BAD ADVICE given on these self help forums. Although what has been suggested would work it is totally wrong and BAD ADVICE.


225.30 Number of Supplies.
Where more than one building or other structure is on the same property and under single management, each additional building or other structure that is served by a branch circuit or feeder on the load side of the service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.
(A) Special Conditions. Additional feeders or branch circuits shall be permitted to supply the following:
(1) Fire pumps
(2) Emergency systems
(3) Legally required standby systems
(4) Optional standby systems
(5) Parallel power production systems
(6) Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability
(B) Special Occupancies. By special permission, additional feeders or branch circuits shall be permitted for either of the following:
(1) Multiple-occupancy buildings where there is no space available for supply equipment accessible to all occupants
(2) A single building or other structure sufficiently large to make two or more supplies necessary
(C) Capacity Requirements. Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of 2000 amperes at a supply voltage of 600 volts or less.
(D) Different Characteristics. Additional feeders or branch circuits shall be permitted for different voltages, frequencies, or phases or for different uses, such as control of outside lighting from multiple locations.
(E) Documented Switching Procedures. Additional feeders or branch circuits shall be permitted to supply installations under single management where documented safe switching procedures are established and maintained for disconnection.

Only one circuit is allowed to be installed and anything more could cause problems should there be a need to make a claim on the homeowner’s insurance.

And people ask why Joe did what he did.

Alectrician
08-14-2008, 09:04 PM
shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.

Gah!

Somewhere in there (not there specifically but in the code) it says you can also run a 240 circuit.....I was sure of it. It was covered a few months ago in a thread....somewhere.....I think.....maybe. There is an exception for lighting circuits also.



Well....I couldn't find it.

Looks like one circuit legal maximum. MWBC (2 hots+1 neutral) is considered one circuit. I don't see how it could hurt anything but I don't make the rules.

Bob NH
08-15-2008, 05:35 AM
Bringing electricity from main panel to sub-panel @ shed 20 feet away. I'm using #12 THHN conductors in 3/4" conduit with two conductors providing 240V to a dedicated air conditioner outlet and two conductors for two separate 120V, 20A outlet circuits for hand tools, etc. My question is do I need to run two separate neutral conductors for those 120V circuits or is one sufficient? Thanks in advance for your help.

The original post said "sub-panel @ shed". That is the legal and correct way to serve the shed. It is also more convenient for the purpose of running multiple circuits. A 4-circuit subpanel is not that expensive.

It would be easy to pull #10 to the subpanel and that would be enough for the A/C and hand tools. Not many people use a Skil Saw in the left hand and a SawZall in the right hand.

If I wanted a compressor in the shed I would run #8s.

jwelectric
08-15-2008, 05:59 AM
Lord I sure understand why I go out every day and see things that were a joke from the first day. It is due to the theory that if it works it must be right.

225.39 Rating of Disconnect.
The feeder or branch-circuit disconnecting means shall have a rating of not less than the calculated load to be supplied, determined in accordance with Parts I and II of Article 220 for branch circuits, Part III or IV of Article 220 for feeders, or Part V of Article 220 for farm loads. Where the branch circuit or feeder disconnecting means consists of more than one switch or circuit breaker, as permitted by 225.33, combining the ratings of all the switches or circuit breakers for determining the rating of the disconnecting means shall be permitted. In no case shall the rating be lower than specified in 225.39(A), (B), (C), or (D).
(A) One-Circuit Installation. For installations to supply only limited loads of a single branch circuit, the branch circuit disconnecting means shall have a rating of not less than 15 amperes.
(B) Two-Circuit Installations. For installations consisting of not more than two 2-wire branch circuits, the feeder or branch-circuit disconnecting means shall have a rating of not less than 30 amperes.
(C) One-Family Dwelling. For a one-family dwelling, the feeder disconnecting means shall have a rating of not less than 100 amperes, 3-wire.
(D) All Others. For all other installations, the feeder or branch-circuit disconnecting means shall have a rating of not less than 60 amperes.

If you're going to do something at least do it right of just leave it alone. If you are going to give advise give correct advise or just be quite.

EDITED TO ADD:

Let’s not forget all those answers to questions that have not as yet been ask such as the other requirements for this installation

Article 225 requires that a disconnect be installed at the building that will disconnect all incoming ungrounded conductors, 225.31

This disconnect is required to be rated as service equipment, 225.36

If there is going to be more than one circuit in that building such as one for the lights and another for receptacles then a minimum of 30 amp circuit MUST be installed.
Should there be more than two circuits out there then a minimum of 60 amp circuit MUST be installed and this will require at least a #6 copper conductor that CAN’T be NM nor SE cable.

The circuit installed will require both a neutral and an equipment grounding conductor. 250.32

A grounding electrode system is required at this building, 250.32.

This list goes on and on. There are several questions that have not yet been asked about the PROPER way to make this installation that carries some very strong life safety issues.

We need to stop giving out our opinions and “it will work” advice and start giving out correct advice to those who are seeking knowledge on how to make installations.

Juan for the road
08-15-2008, 07:30 AM
Lord I sure understand why I go out every day and see things that were a joke from the first day. It is due to the theory that if it works it must be right.


We need to stop giving out our opinions and “it will work” advice and start giving out correct advice to those who are seeking knowledge on how to make installations.

Amen.

The code is code for a reason,even if most of us can't understand it.
Follow the code and you're in good shape...only an idiot would disregard it or not reference it.There's just too much at risk.

I will only follow advice given along with specific code references.If the advice sounds "anecdotal" I skip it.

The original question is very basic and common,been asked a thousand times over,everywhere in the country.Most electrical apprentices with 6months experience should nail this one.

Rest easy if you follow JW.

Alectrician
08-15-2008, 09:37 AM
The original post said "sub-panel @ shed".

Oh yeah. I guess that since JW went all blah blah blah, I assumed that he read the post.

So......Back to the original post and the original question, based on the info given.......you only NEED one neutral but two is better.

hj
08-15-2008, 09:47 AM
So......Back to the original post and the original question, based on the info given.......you only NEED one neutral but two is better.

You are therefore assuming that they are going to be on different legs of the power supply, otherwise a single neutral could be overloaded by usage of both feeds at the same time, also assuming it were not improper to do it in the first place and also more time and trouble than it is worth rather than installing a sub panel in the garage.

http://terrylove.com/forums/images/misc/progress.gif

Alectrician
08-15-2008, 09:12 PM
You are therefore assuming that they are going to be on different legs of the power supply, otherwise a single neutral could be overloaded by usage of both feeds at the same time, also assuming it were not improper to do it in the first place and also more time and trouble than it is worth rather than installing a sub panel in the garage

Holy run on sentance Batman :eek:

Try to keep up. He IS putting a sub in the shed.


Bringing electricity from main panel to sub-panel @ shed 20 feet away

It was a little unclear but that's what he said.

jwelectric
08-16-2008, 03:08 AM
Oh yeah. I guess that since JW went all blah blah blah, I assumed that he read the post.

So......Back to the original post and the original question, based on the info given.......you only NEED one neutral but two is better.
so you think it would be a good idea to parallel the neutral to the subpanel?

Chris75
08-16-2008, 04:01 AM
It would be easy to pull #10 to the subpanel and that would be enough for the A/C and hand tools. Not many people use a Skil Saw in the left hand and a SawZall in the right hand.

If I wanted a compressor in the shed I would run #8s.



Lord I sure understand why I go out every day and see things that were a joke from the first day. It is due to the theory that if it works it must be right.

225.39 Rating of Disconnect.

(D) All Others. For all other installations, the feeder or branch-circuit disconnecting means shall have a rating of not less than 60 amperes.

If you're going to do something at least do it right of just leave it alone. If you are going to give advise give correct advise or just be quite.

EDITED TO ADD:

Let’s not forget all those answers to questions that have not as yet been ask such as the other requirements for this installation



This disconnect is required to be rated as service equipment, 225.36

If there is going to be more than one circuit in that building such as one for the lights and another for receptacles then a minimum of 30 amp circuit MUST be installed.
Should there be more than two circuits out there then a minimum of 60 amp circuit MUST be installed and this will require at least a #6 copper conductor that CAN’T be NM nor SE cable.






Mike, not to burst your bubble, but no where in the NEC tells you what size conductors to run to a seperate structure, the only thing the NEC requires is the Rating of a Disconnect, not the rating of the conductor....




4-26 Log #2194 NEC-P04

Final Action: Reject

(225.39, FPN )

Submitter: David Williams, Lansing, MI

Recommendation: Revise as follows:
The rating feeder or branch-circuit disconnecting means shall have a rating of
not less than the load to be supplied, determined in accordance with Parts I and
II of Article 220 for branch circuits. Parts III or IV of Article 220 for feeders,
or Part V of Article 220 for farm loads. In no case shall the rating be lower
than specified in 225.39(A), (B), (C), or (D).

FPN: The rating of the overcurrent device protecting the feeder does not need
to be rated to the minimum rating in this section.

Substantiation: The code section specifies the minimum rating of the
disconnect and is not clear that the feeder or branch circuit needs to be rated
for this minimum rating. As an inspector, I am not positive if this section only
applies to the rating of the disconnect or does this mean that the minimum size
of a feeder to a building should be 60 amperes.
Just trying to clear up a concern.

Panel Meeting Action: Reject

Panel Statement: An additional FPN is not necessary. The title of 225.39
defines the requirement as solely being the rating of the disconnect.

Number Eligible to Vote: 10

Ballot Results: Affirmative: 10

hj
08-16-2008, 07:26 AM
Holy run on sentance Batman

It is "sentEnce" since we are going pedantic. But not the king of runons. That was a whole page in an educational journal.

Alectrician
08-16-2008, 08:33 AM
so you think it would be a good idea to parallel the neutral to the subpanel?

I know a trick question when I see it :rolleyes:

I think separate neutrals is a better idea, especially when a HO is doing the work. They don't seem to be able to tighten wire nuts properly.



It is "sentEnce" since we are going pedantic

Now you want me to make me get out the dictionary?

I know it's sentence. It is a common mistake of mine along with many others.;)

jbfan74
08-16-2008, 08:37 AM
Mike: I agree with Chris. I just completed an install of 30 amp 240 to a stand alone shed, with a 60 amp disco on the building and passed.

Chris75
08-16-2008, 08:54 AM
Mike: I agree with Chris. I just completed an install of 30 amp 240 to a stand alone shed, with a 60 amp disco on the building and passed.


And you should, 225.39 is titled, Rating of Disconnect.
not sure how people end up with thinking the wire size is related to that.

Chris75
08-16-2008, 08:58 AM
Bringing electricity from main panel to sub-panel @ shed 20 feet away. I'm using #12 THHN conductors in 3/4" conduit with two conductors providing 240V to a dedicated air conditioner outlet and two conductors for two separate 120V, 20A outlet circuits for hand tools, etc. My question is do I need to run two separate neutral conductors for those 120V circuits or is one sufficient? Thanks in advance for your help.

I'm still a little confused on the first sentence, and with what the rest of the post describes.

Old Coot
08-16-2008, 05:41 PM
Apologies..my original description was lousy. The 20-foot feed to the shed is from a subpanel. Within that subpanel will be a two-pole 20A breaker for my 240V air conditioner circuit and two 20A single-pole breakers for the 120V circuits. So in the conduit to the shed will be (for example) two black #12 THHN's for the 240V outlet and two red #12 THHN's for the 120V outlets. There will also be a green #10 THHN for ground. Question was how many neutral (white) #12 THHN's need to be in that conduit.

hj
08-16-2008, 05:56 PM
Again, it depends on how you wire them. If they are to two different power legs you can get by with one, but realize that there is a downside to doing so. Safer is separate neutrals for each circuit, then you do not have to worry about burning things out if you lose the neutral, nor burning something down if you were to switch breakers and wind up with both on the same leg.

Alectrician
08-16-2008, 11:23 PM
Code says only one circuit can be run to the shed. All the info is above.

jwelectric
08-17-2008, 03:21 AM
Okay I agree that it is the disconnect that 225.39 is addressing instead of the circuit itself but that don’t change the fact that only one circuit is allowed by 225.30 or the disconnect outlined in 225.31 or the fact that the disconnect must be service rated per 225.36.
This building will also be required to have its own electrode system as outlined in 250.32 as well.

What you all are telling this poor guy is nothing short of wrong in the fact that he is to supply a sub panel with several different circuits or for that matter feeding the building with more than one circuit.

hj
08-17-2008, 07:12 AM
It sounds like he is going to do it anyway, so at least we can help him do it safely.

Old Coot
08-17-2008, 10:44 AM
Thanks all for the information; it's been an experience hearing from each of you. And again, apologies for initial poor explanation of what I'm trying to do.

Yes, I'm going to do it anyway but using two neutral conductors as suggested. If I sound stubborn, here's why:

Apparently if I was simply running the new 240V outlet and the two 120V outlets from the subpanel within the same structure (either using NM behind drywall or conduit if exposed) I would be "legal" even if the distance was much greater than 20 feet. I'm also guessing that that "legality" probably would extend to a shed attached to the structure holding the subpanel. So why is it all of a sudden "illegal" (or hazardous) if all the wiring is in conduit (buried well below code requirements)simply because there's a bit of open space between the structures.

I'll defer to anyone who says what I'm going to do is "illegal", but can someone get it into my thick head why it is either illegal or hazardous?

Mikey
08-17-2008, 12:58 PM
So could someone give me a step-by-step guide, with NEC citations, as to how to proceed if I want to have 1 20A 240V circuit, and 2 20A 120V circuits, with a maximum load of 24A total, in an unattached shed 50' from the house?

Speedy Petey
08-17-2008, 01:44 PM
So could someone give me a step-by-step guide, with NEC citations, as to how to proceed if I want to have 1 20A 240V circuit, and 2 20A 120V circuits, with a maximum load of 24A total, in an unattached shed 50' from the house?
The ONLY way to do this legally is by installing a sub-panel, so answering your questions "as asked" would be non-compliant and dangerous.

Alectrician
08-17-2008, 02:00 PM
can someone get it into my thick head why it is either illegal or hazardous?

I don't think you will get an answer to this. I am always interested to hear input though. Another person's perspective can be enlightening. My guess is that the code was written for larger structures bacause it make sense to have a separate system for a sepatate building.

It applies to a shed or garage because there are no exceptions written in re: size.

If I were doing the work, it would be almost just as easy to put a sub at the shed and split off from there so I'd avoid the liability and comply with code.



answering your questions "as asked" would be non-compliant and dangerous.

Well....non compliant anyway.


Just run a sub.


3/4 PVC. 18" deep from your house panel to the shed sub. Strap it coming up the wall.

Pull in three #8 THWN (two blacks and a white) and one #10 green. Colored tape is also not compliant....but that's a whole nother thread.

Terminate the ground wire in a ground bus kit that will screw to your panel enclosure. Make sure the neutral bus is isolated from the enclosure. Terminate the other end on a 2 pole 50 amp breaker. The ground and neutral wil go on the same bus if the panel is the service. Look and see how the other circuits are terminated.

Run your 120 and 240 circuits from the new sub.


Or stick with plan A.

Mikey
08-17-2008, 02:53 PM
The ONLY way to do this legally is by installing a sub-panel, so answering your questions "as asked" would be non-compliant and dangerous.
No, step one in the answers is "You need to install a subpanel." Now, go on to step 2...

Mikey
08-17-2008, 02:56 PM
Pull in three #8 THWN (two blacks and a white) and one #10 green. Colored tape is also not compliant....but that's a whole nother thread.

Terminate the ground wire in a ground bus kit that will screw to your panel enclosure. Make sure the neutral bus is isolated from the enclosure. Terminate the other end on a 2 pole 50 amp breaker. The ground and neutral wil go on the same bus if the panel is the service. Look and see how the other circuits are terminated.

Run your 120 and 240 circuits from the new sub.


Or stick with plan A.

Sounds good, but drawing from NEC cites above,

Why not a 60A breaker?

Why not a grounding electrode at the shed?

Alectrician
08-17-2008, 03:01 PM
Why not a 60A breaker?


That's all I have on my truck :D




Why not a grounding electrode at the shed?

Assuming no metalic piping to a "shed"..........right?

Chris75
08-17-2008, 04:29 PM
So could someone give me a step-by-step guide, with NEC citations, as to how to proceed if I want to have 1 20A 240V circuit, and 2 20A 120V circuits, with a maximum load of 24A total, in an unattached shed 50' from the house?

Art 225. is a pretty short and easy section to follow, check it out.

Chris75
08-17-2008, 04:30 PM
That's all I have on my truck :D





Assuming no metalic piping to a "shed"..........right?

You still need a grounding electrode system. unless of course you only ran 1 circuit out to the structure.

Speedy Petey
08-17-2008, 05:55 PM
No, step one in the answers is "You need to install a subpanel." Now, go on to step 2...No.

Even someone as loving and patient as me gets tired of holding DIYer's hands through jobs they are not knowledgeable enough to do.

If you need "a step-by-step guide" to installing a sub-panel maybe it's a job better left to a pro.
I don't ask my accountant for a a step-by-step guide to doing my taxes. SHE is the pro, I let her do them.

If I am wrong about you sorry, there is a lot of good (and some not so good) information out there. You just need to figure out which is which.

Speedy Petey
08-17-2008, 05:56 PM
You still need a grounding electrode system. unless of course you only ran 1 circuit out to the structure.Right!

Didn't we go over this already?:confused: :rolleyes:

Chris75
08-17-2008, 05:58 PM
Right!

Didn't we go over this already?:confused: :rolleyes:

O'yeah, lots of times.

Alectrician
08-17-2008, 07:01 PM
You still need a grounding electrode system. unless of course you only ran 1 circuit out to the structure.

I thought I learned from the message boards that no ground rod was needed if there was no piping that connected the structures. My bad.



Even someone as loving and patient as me gets tired of holding DIYer's hands through jobs they are not knowledgeable enough to do.

Heh heh....good one. When I hear "loving and patient" I automatically think of you. You might want to take a break from the DIY boards and go to your happy place. :)


BTW, I think the guy could handle the job.

Speedy Petey
08-17-2008, 09:30 PM
I thought I learned from the message boards that no ground rod was needed if there was no piping that connected the structures. My bad.This has been NEC 250.32 for quite a long time. Even before internet message boards.

Mikey
08-18-2008, 03:49 AM
If you need "a step-by-step guide" to installing a sub-panel maybe it's a job better left to a pro.
I don't ask my accountant for a a step-by-step guide to doing my taxes. SHE is the pro, I let her do them.
Interesting parallel. Just as the tax code is pretty useless in helping someone prepare his taxes, the NEC is pretty useless in guiding someone through even simple electrical work. Kind of like using a dictionary to learn a foreign language.

There are lots of DIYers out there who are perfectly capable of following clear directions, and those who like to know the code which resulted in those directions deserve extra credit, IMHO. This forum could be a valuable resource to provide that guidance.

Having said that, even I am appalled at some of the ignorance displayed in the questions asked...