Sharing Neutrals Money Thing?

Bubbles

Is sharing neutrals just a money thing? How much more could it cost to pull one more #12 through a conduit or running 12/4 MC? I could see for buildings over 12,500 square ft or something that will probably have good electricians doing things but on small things with multiple techs messing with panels why even share the neutral? If I had a nickel for every service call where someone moved breakers around without knowing the neutral is shared I would have a nice chunk.

Must be a political = money thing is all I can see??

mahlere

i get hundreds of dollars for every service call like that...forget
nickels...


extra nuetrals could mean higher derating factor...larger conduit....larger wire...more conduit....more labor....more resources....

how long have you been in this industry?

macmikeman

When 2008 is adopted in your areas, then it will become a slight bit more money thing, because then you will have to ty wrap multiwire branch circuit conductors together inside of the panels to identify them as such.

mdshunk

Bubbles.. how long you been in this trade anyhow? Multiwire branch circuits always were and always will be a way of life. Yes, it is a mony thing. Properly installed, they present no hazard and no real problems. Consider that the service drop or lateral to every building is a shared neutral circuit. I'm not sure where this "no multiwire branch circuits" brew-ha-ha came from teh last couple of years, but it's just silly, and I wish people would just knock it off. I refuse to install wiring for the dumbest possible person who might come along and monkey with it.

Speedy Petey

My sentiments exactly.

I get very tired of folks throwing around the old "It's a money thing" knee jerk reaction to everything they don't understand or don't agree with.

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fridaymean

AWESOME!

jrclen

Interesting post. I use multi wire circuits quite often. Where ever it is appropriate and code complient, in my experience. The money you mentioned is not mine. It is my customers money. Multi wire circuits seem just fine to me. A twelve 3 makes a nicer home run than 2 twelve 2's in my humble opinion. And in conduit I have to think about derating. If we kept hacks out of the panels, there would be no problem with moving breakers around causing problems. I guess people in my area must be a little smarter then yours, because I get very few service calls due to problems with the multi wire circuits themselves.

frenchsparky

Really i dont have much issuse with MWBC at all either as long you know what it will plan to used for it genrally dont have much issusese. the only curpit i have to watch out is the hamaromic loads aka non liner loads like computer and electronic lighting loads.

those part i useally automatic upsize the netural on MWBC this pratice is more common on 3 Ø system but single Ø system it not too bad but still be a wise idea [ but becarefull if you run single Ø off from 3 Ø legs ]

i get few call from MWBC from time to time on commercal side will useally a dolt will not think about the MWBC and when replace the device[s] and some case they unhook the pigtail [ ] on netural side ya know the rest when the netural lifted. it dont matter which voltage the MWBC run

for resdential area to me it fine but for HO or some Hacks they will get a funny idea try to mess around this.

that part it becomeing a routine calls for me to go after their mess espcally try to run GFCI on MWBC's [ we dont have AFCI on yet per our state code ]



Merci, Marc

Tmrrptr

Edison type circuits are a great way to save in labor and material costs.
It also makes a less congested and cleaner looking panel.
r

Sparky Joe

"Edison type circuits" that term is a first for me.
Kinda ironic too because Edison was opposed to AC electricity

mdshunk

I think he means knob and tube.

macmikeman

You know I have put in multiwire branch circuits my whole career, 30+years, and not one single house catches fire yet (except that time the homeowner got permission from a gc to install his own insulation and shot his staples thru the romex running up the center line of the studs. ) The other's are right, they are fine so long as the diy hacks stay away from the panel. But with the new dwelling afci required locations coming in 2008, coupled with no exceptions in the code for existing dwellings with mwbc any new remodel/ extensions to existing mw circuits are going to get really tricky. If you are lucky enough the panel will be CH style so you can use the double pole afci breakers. And Seimans has a two pole afci also, but they were not really in use much in the USA,before 1980 so older houses- forget about using existing mwbc home runs for the most part.

HVAC_NW

There is no technical issue in sharing a neutral between two opposing poles as the neutral only carries the difference of the two and that is never greater than the full capacity of one breaker.

jrclen

Well now, I'm all for those things. Could you bring me up to speed on what exactly an Edison type circuit is? I'm always willing to learn in my quest for cleaner looking, less congested panels.

jrclen

You are correct, of course, Marc. I do consider the harmonics on non linier loads. In 3 phase commercial installations for offices I do up-size the neutral for harmonics on both the 120 and 277 loads you mentioned. I attended a seminar on this subject, and the consensus was, the harmonics from computer systems in the home on single phase 120 MWC would not be a heating problem on the neutral. Correct me if I'm wrong. In fact, if you travel 45 miles west, I'll buy you a beer.

Bubbles

All I'm saying is I've had over 100 calls min in last 7-10 yrs of burnt Neutrals from DIY or whomever. Folks get in panel and move breakers around over the years not knowing about this and they put the two hots in phase. Normally no markings on wire and I've rarely seen them on a two pole breakers like they are supposed to be. I've seen upwards of 42amps (somehow) flowing through a #12 neutral. The calls have been from flickering lights to 1/2 house out but it was all because of loose or burnt neutrals. I don't see why you need to share in residential. The price is miniscule but Commercial I can see why it's practical. I do mostly troubleshooting for old residential houses and some commercial so it doesnt matter to me. Just more calls$$ I can't wait til 08' when Afci breakers are installed $$$$

Speedy Petey

Burned neutrals are RARELY caused by overloading. 99% of the time I see them it is due to an improper or failed connection.

If you are so against MWBC's then I suggest you call your poco and tell them you demand two neutrals run with each new service since every residential service is simply one big multi-wire circuit.

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jbfan

If most of what you do is trouble shoot old house, then the arc fault change will not affect you.
You said that you rarely see mwbc on double pole breakers. Seems to me that for the most part that is not required either. Only when the circuits land on the same yoke.

Why do you complain about something that seems to make you the most money anyway?

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mdshunk

I'm calling BS right now. Unless Bubbles lives in a town called DIYville, there's no way that he/she's had 100 calls for multiwire branch circuit problems. I'm proud of the fact that I'm in a heck of a lot of different houses in a week's time, and I can count on one hand the times I've found this problem. I'm certainly not gong to worry about the fact that there are many ways that a determined hack DIY can screw up his electrical system without realizing it. This is among them. Big deal... they got what they had coming, I say.

JohnJ0906

The MWBC is standard wiring practice, and has been for many years. The person who doesn't understand, shouldn't be screwing around in panels. Period.

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John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC