# sharing the neutral on 12/3?



## bushwickbill (Jan 17, 2010)

I am planning on pulling a 12/3 wire from the panel up to attic so I can rough-in two new circuits. One circuit is going to have 11 Pot lights on it, The other is a Bathroom heat lamp fan combo. I am just a little unsure on the rules as to what kinds of things cannot share a neutral? I know that motor loads need their own circuit(neutral). But what about a Bathroom heat lamp fan combo, About 500-700 Watts total? I am unsure of total Amps drawn from this said unit? Can that unit share the neutral from the 12/3 with the pot light circuit?
thanx


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## TOOL_5150 (Aug 27, 2007)

It can share the neutral, but you are going to have to use a 2p breaker or use a handle tie, which design-wise might suck.

I would pull two 12/2's


~Matt


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## Teaspoon (Jan 10, 2009)

TOOL_5150 said:


> It can share the neutral, but you are going to have to use a 2p breaker or use a handle tie, which design-wise might suck.
> 
> I would pull two 12/2's
> 
> ...


 I agree I would definately pull two 12/2's.


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## Dennis Alwon (May 9, 2009)

I don't know about Canada but the days of MYBC in a residence in the US are numbered. The use of arc faults have slowed it to a halt.


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## HARRY304E (Sep 15, 2010)

Dennis Alwon said:


> I don't know about Canada but the days of MYBC in a residence in the US are numbered. The use of arc faults have slowed it to a halt.


Dennis . I thought we could use two pole AFCI breakers?:001_huh:.

I would run seperate 12/2s anyway.:thumbsup:


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## Dennis Alwon (May 9, 2009)

HARRY304E said:


> Dennis . I thought we could use two pole AFCI breakers?:001_huh:.
> 
> I would run seperate 12/2s anyway.:thumbsup:


 You can but not everyone makes a DP combination AFCI. Also if one circuit has a problem both go off.


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## Shockdoc (Mar 4, 2010)

Is 12/3 still double the price of 12/2 ? Still working off the same 1000 ft roll I aquired at HD.


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## rexowner (Apr 12, 2008)

Shockdoc said:


> Is 12/3 still double the price of 12/2 ? Still working off the same 1000 ft roll I aquired at HD.


Not quite, but 12-2-2 where i am costs more than 12-3 + 12-2, which
kinda sux.


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## TOOL_5150 (Aug 27, 2007)

rexowner said:


> Not quite, but 12-2-2 where i am costs more than 12-3 + 12-2, which
> kinda sux.


Yeah, Ive ran flex and thhn instead of that expensive crap.

~Matt


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## stackappartment (Apr 4, 2010)

rexowner said:


> Not quite, but 12-2-2 where i am costs more than 12-3 + 12-2, which
> kinda sux.


Whats funny is at the supply house 12-2-2 is much cheaper than 12-4 just different color wires is the difference. must be a supply and demand thing


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## doubleoh7 (Dec 5, 2009)

stackappartment said:


> Whats funny is at the supply house 12-2-2 is much cheaper than 12-4 just different color wires is the difference. must be a supply and demand thing


 


Supply and command. Duhh.....:laughing::laughing:


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## Southeast Power (Jan 18, 2009)

TOOL_5150 said:


> It can share the neutral, but you are going to have to use a 2p breaker or use a handle tie, which design-wise might suck.
> 
> I would pull two 12/2's
> 
> ...


I would go with 14/3 on a 2 pole or two 14/2s for that small of a load. But, I'm not used to cramming #12 solid into junction boxes.


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## bobelectric (Feb 24, 2007)

I thought a pot light was a 400 watt mh.


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## wayne g (Nov 28, 2010)

The 12/3 will work but make sure the red & black legs are on a different phase so that the neutral carrys the unbalance between the 2 hot legs only.


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## guest (Feb 21, 2009)

Good gods man, don't use a MWBC!! They are the root of all that is evil in the electrical world! The electrons don't behave properly and you will burn the house down!!:jester:




Wait for it............................................
















Cue BBQ in 3, 2, 1............:whistling2:


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## BBQ (Nov 16, 2010)

mxslick said:


> Good gods man, don't use a MWBC!! They are the root of all that is evil in the electrical world! The electrons don't behave properly and you will burn the house down!!:jester:


That is equal to all the other stupid crap you have posted about MWBCs. :thumbsup:






> Wait for it............................................
> 
> 
> 
> ...


I will always be here to rag on foolish posts. :laughing:


BTW, I would probably avoid a MWBC for this circuit due to the handle tie rule and AFCI issues. :thumbsup:


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## Jlarson (Jun 28, 2009)

:laughing::laughing:

I would avoid the "evil" MWBC's in this case too cause of the same reason BBQ stated about handle ties and AFCI's.


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## guest (Feb 21, 2009)

BBQ said:


> That is equal to all the other stupid crap you have posted about MWBCs. :thumbsup:


Now that was just mean and downright rude. :glare: We agreed on the other forum a long time ago that since we work in different specialties and have widely differing experiences, that we each have valid reasons. 



BBQ said:


> I will always be here to rag on foolish posts. :laughing:
> 
> 
> BTW, I would probably avoid a MWBC for this circuit due to the handle tie rule and AFCI issues. :thumbsup:


{Cue sultry female computer voice} Identity confirmed. Have a nice day. :thumbsup:

Even with the AFCI and handle tie rule I am still surprised to see you avoiding a MWBC....are you feeling ok? 

To the OP: In all seriousness, there is really no problem with using a MWBC for what you propose. Just make sure the hots are on opposite legs, you use a handle tie or DP AFCI (if your area requires them) and it will work fine. 

The MWBC debate is a long-running gag between me and BBQ. He thinks I'm totally wrong and I think he's a fuddy-duddy. :wheelchair::laughing:


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## Magnettica (Jan 23, 2007)

bushwickbill said:


> I am planning on pulling a 12/3 wire from the panel up to attic so I can rough-in two new circuits. One circuit is going to have 11 Pot lights on it, The other is a Bathroom heat lamp fan combo. I am just a little unsure on the rules as to what kinds of things cannot share a neutral? I know that motor loads need their own circuit(neutral). But what about a Bathroom heat lamp fan combo, About 500-700 Watts total? I am unsure of total Amps drawn from this said unit? Can that unit share the neutral from the 12/3 with the pot light circuit?
> thanx


Pot lights? Do you plan to grow a little, "sticky-sticky"?


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## BBQ (Nov 16, 2010)

mxslick said:


> Now that was just mean and downright rude. :glare: We agreed on the other forum a long time ago that since we work in different specialties and have widely differing experiences, that we each have valid reasons.


You have never explained the electrical magic that happens at the OCPD that makes a common neutral on the line side of it OK and on the load side of it evil. 

Seriously, if you could provide a valid explanation maybe I would see things differently.

All you have given me is anecdotal experiences and your feelings about it.





> Even with the AFCI and handle tie rule I am still surprised to see you avoiding a MWBC....are you feeling ok?


The AFCI issue makes it to much of a PITA.

Of course I am a commercial guy so AFCIs are not much of a worry yet.


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## Magnettica (Jan 23, 2007)

*electrical magic* :laughing:


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## BBQ (Nov 16, 2010)

Magnettica said:


> *electrical magic* :laughing:


It is a highly technical and scientific term. :thumbsup:


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## BBQ (Nov 16, 2010)

mxslick, The other day I happened to be looking at this instruction sheet (yeah I know I am odd ) for some pro audio sub woofers and I just remembered they actually show using a common neutral. :laughing:

http://www.meyersound.com/pdf/products/concert_series/700-hp_oi-A.pdf

Take a look at figure 2.1 on page 5.


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## slickvic277 (Feb 5, 2009)

who is this mxslick character???


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## guest (Feb 21, 2009)

BBQ said:


> You have never explained the electrical magic that happens at the OCPD that makes a common neutral on the line side of it OK and on the load side of it evil.
> 
> Seriously, if you could provide a valid explanation maybe I would see things differently.
> 
> All you have given me is anecdotal experiences and your feelings about it.


And you still refuse to acknowledge that maybe, just maybe, someone with 26 years of experience in my given specialty has encountered enough problems caused by shared neutrals _*in my specific applications*_, which were cleared up solely by re-pulling dedicated neutrals. Anecdotal my a**. 

Whether you believe that MWBC's don't work for _*my applications*_ or not I really don't give a damn anymore because I don't wire up huge commercial buildings and as far as I know from our past dialogues you do not wire up cinemas or home screening rooms. So how dare you sit here and challenge me in such a manner when you do not know me, my work or my specific trade. I sure as hell don't challenge YOUR methods or integrity, as I have litlle or no practical experience in commercial work such as what you do. I am not the first or only technician in my trade to demand dedicated neutrals for all sound and A/V equipment and I will not be the last. 

You still refuse to acknowledge that I have publicly conceded that MWBC's have their place in many applications _*OTHER THAN high-end technical or audio systems. *_

As for the WHY, my theory is that the neutral bus of a panel or feeder has a LOT less impedance that a single #12 or #10 conductor which may explain why moving that common reference point farther away from the utilization equipment solves the problems I have encountered. 

I am not an electrical engineer and don't care about WHY MWBC's do not get along with the equipment I deal with, I just do what I have to, to ensure what I install works reliably and without hum, noise or premature failure issues. 







BBQ said:


> The AFCI issue makes it to much of a PITA.
> 
> Of course I am a commercial guy so AFCIs are not much of a worry yet.


Thankfully that is true, but just wait, the NEC will somehow work the AFCI requirement into commercial when they realize all the carnage they will prevent. :whistling2:



BBQ said:


> mxslick, The other day I happened to be looking at this instruction sheet (yeah I know I am odd ) for some pro audio sub woofers and I just remembered they actually show using a common neutral. :laughing:
> 
> http://www.meyersound.com/pdf/products/concert_series/700-hp_oi-A.pdf
> 
> Take a look at figure 2.1 on page 5.


Meyer sound equipment is deliberately designed to deal with the kind of noisy, unstable power that is part and parcel of live sound reinforcement and it is a totally different environment from a cinema or screening room where ANY extraneous noise or hum cannot be tolerated. A minor bit of noise or hum in a huge concert venue would be inaudible, whereas in a cinema or screening room it would be intolerably noticeable. Apples and oranges. 

With that said, Meyer sound is high quality gear for it's intended application, but it is NOT suitable for cinema sound at all. Cinema sound is designed for higher accuracy and clarity, whereas Meyer gear and the like is designed for broad coverage and sheer volume (loudness.) 



slickvic277 said:


> who is this mxslick character???


BBQ's worst nightmare... :laughing: We have had a variation of this debate for a few years now on other forums. 


For the masses here who don't know, I have had over 30 years of experience divided between electrician and cinema service and installation tech. Majority (since I have been self-employed as a cinema tech for the last 14 years) in the cinema field. I have had many job offers from major EC's which I have turned down as my passion is more in cinema.


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## Jlarson (Jun 28, 2009)

mxslick said:


> BBQ's worst nightmare... :laughing:
> 
> 
> For the masses here who don't know, I have had over 30 years of experience divided between electrician and cinema service and installation tech. Majority (since I have been self-employed as a cinema tech for the last 14 years) in the cinema field. I have had many job offers from major EC's which I have turned down as my passion is more in cinema.


Vic missed your welcome thread, ya know the one BBQ and 480 turned ****. :laughing:


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## guest (Feb 21, 2009)

LOL good one..I had forgotten about that (after having nightmares for days). :laughing:

Too bad I fixed the dyslexic spelling after you quoted me. (LOL now your edit made this line pointless.)

I think BBQ could benefit from your signature line too.


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## Jlarson (Jun 28, 2009)

mxslick said:


> Too bad I fixed the dyslexic spelling after you quoted me. (LOL now your edit made this line pointless.)


:laughing::laughing:


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## HARRY304E (Sep 15, 2010)

Jlarson said:


> BBQ and 480 turned ****. :laughing:


:laughing::laughing:


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## electricmanscott (Feb 11, 2010)

Jlarson said:


> Vic missed your welcome thread, ya know the one BBQ and 480 turned ****. :laughing:


Am I born gay or can I turn gay :laughing: :laughing:


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## guest (Feb 21, 2009)

I'm not sure what's more disturbing....the direction this thread has taken or the fact that electricmanscott found that thread on that particular forum. :laughing:

To get back on topic and hopefully keep the mods from locking this thread...

I have already stated that I agree the OP could use a MWBC as he describes, as long as he has handle ties or a DP AFCI if it is required in his area. 

I have used, without second thoughts, MWBC's in certain NON-AUDIO/TECHNICAL applications with good results.

I WILL NOT EVER allow MWBC's to be used on ANY sound, technical or other system where either manufacturer's instructions or my own experiences have PROVEN MWBC's to cause trouble. 

So there. :tt2:


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## Jlarson (Jun 28, 2009)

electricmanscott said:


> Am I born gay or can I turn gay :laughing: :laughing:


There is a user named Ken :lol:


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## bobelectric (Feb 24, 2007)

The last time I heard anyone yell "How Dare You?", was on a M.A.S.H. rerun, coming from Hot Lips .


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## guest (Feb 21, 2009)

bobelectric said:


> The last time I heard anyone yell "How Dare You?", was on a M.A.S.H. rerun, coming from Hot Lips .


She stole it from me, that minx. :laughing:


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