Went to look at a 200 amp upgrade job today and found two 2 wire (with ground) Romexes being used as multiwire circuits. The black and the white were the two lines and the bare was the neutral. Looked like it was done at construction, 30 year old house out in the sticks.

I've definitely never seen that before!

Another reason why I hate multi wire circuits!!

O.k., brace for a "blast" from iwire!!

Not that I ever think that was code, what were the loads they were feeding?

This sort of thing happens when a guy screws up the rough and finds it at trim. Instead of admitting it and eating the backcharge for drywall and paint they cheat.
My wife caught some 3 ways wired the same way, using the bare as a current carrying conductor.

I don't like any mis-wired circuit.

Really wondering how you would wire a electric dryer or range?

Those are both multiwire branch circuits.



[This message has been edited by iwire (edited 01-03-2007).]

It would not surprise me if some of the projectors you use require multi wire branch circuits.

An electrician who is uncomfortable running MWC's -- Kind of like a doctor who is afraid of using his stethescope. It must be very un-nerving dealing with that great big service entrance MWC while doing a panel changout. Probly not wiring many large homes either. I'd like to see some of the home runs in said installations, and the bid...

When I was young, wet behind the ears, and had just moved out "on my own," I rented a room in a house that housed several such as I.

My 'introduction' to the trade came when a very upset man appeared one day, looking for one of the other residents. He had hired the guy to do some electric work in his new home, he said, and the guy did something wrong, that 'blew up' hs TV set.

Later, in the course of my work, I was introduced to properly trained, real electricians. The bits and pieces I told of the story made no sense to them.

With hindsight, of course it was not something the 'real' guys had ever dealt with; they had been taught right, and had not done what this self-taught self-appointed "electrician" had done - they had never left an open (or loose) neutral.

Much as I value saving money myself, I draw the line at 'cheating.' I don't hire the local 'aw shucks' guy to do my brakes; nor do I try to do my own haircuts! So many of the problems we encounter (and the pictures we post) are the result of someone trying to 'beat the system.'

It is one thing, in dire circumstances, to try to "McGyver" something; quite another to make such "self-reliance" one of your lifes' basic principles.

Well said Reno

Why are you folks who are against multiwire brach circuits against using them? Is it a liability issue for when the HO later on "upgrades" his electricial system and improperly reconnects the MWBC to the busbar?

I've become a big fan of this type of homerun simply because it saves me money on wire, and on time installing the circuit (s). Why would you not like to make more money? The whole single phase system in a single family dwelling is itself a MWBC!!

Now, the only situtation where I wouldn't use a MWBC is for a computer ckt or some other sensitive electronic circuit, like home theatre/ sourround sound set up where harmonics could be an issue.

Shockme, I can't speak for others, but I have a personal bias in favor of KISS ... keep it simple, stupid ... especially in situations where the wiring method comes 'pre-packed" (romex, MC, etc.), or the system is likely to be worked on by lesser qualified folks (homes, apartments).

I do, in fact, often use shared neutrals. in particular where I am running all the circuits new.

Unfortunately, I've had to sort out too many places where somebody had only heard that 'it was OK to share a neutral' ... then went about re-arranging white wires at random. Or combining several neutrals into one, for a single wire back to the panel.

I suppose my 'moment of truth' came the day I mis-connected some white wires in a ceiling junction box ... and then had the honor of smoking a change machine someone had cobbled onto the circuits; killing the three 'hots' associated with that neutral was not enough to prevent that appliance from getting a nice dose of over-voltage.

I guess the 'lesson' here is that 'all neutrals are not the same,' or, 'we really MUST identify our neutrals.'

Yet, I have seen far too many situations where someone added to a system by grabbing any hot, and any neutral. This works just fine ... until the next problem arises.

Actually, none of the newer ones do.

The manufacturers realized that the xenon lamp ignitors and house lighting dimmers cause too many noise and harmonics issues, with the modern electronic automation systems.

However, it was at one time common practice to have projection consoles with built-in subpanels to serve the projection loads.

As we've discussed before, my bias is against MW branch circuits, where as Reno and many others have related, trouble can easily arise.




[This message has been edited by mxslick (edited 01-03-2007).]

Found a fan motor for a furnace wired using the bare ground as a neutral! The origional neutral had a break in it so someone just used the bare ground.
I've also opened a neutral connection in a j-box not knowing that it is a shared neutral. You hear "Hey, what happened to my computer?" coming from the next office!