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latelifebiker 03-06-2014 01:05 PM

There are 3-conductor cables in my breaker box (???)
UPDATE: If you find yourself gleaning information from this thread, then BE SURE TO READ THE ENTIRE LIST OF POSTINGS. The information here evolves as members add to the detail of the situation. I am quite grateful to all who participated. -llb

I've looked at a lot of circuit breaker panels in my DIY experience, but I've never encountered this... and I'm concerned. Of the several cables leaving the box as part of the original house wiring, TWO of them are 5-conductor cables with insulated black, white, and red wires inside, plus a bare ground.
In both cases, each of the red and black wires is served by a separate 15-Amp breaker, while the common white and the bare ground are connected to their appropriate busses.
My concern is that I seem to recall reading in the past about the inadvisability--perhaps even illegality--of what the writer called a "common ground." It appears to me that such is exactly the case in these four circuits. They are not special 220-volt appliance circuits. Rather each breaker serves some combination of outlets, overhead lights, a ceiling fan,or (egads!) an over-the-stove microwave oven. (One of the new cables I plan to run will serve that microwave.)
Is this situation as dumb as I think it is? I'm renovating our kitchen, and I have to run some new wiring while I have the walls ripped out. Maybe this is a good time to address some flawed past practices in this house.
Thanks. -paul, the latelifebiker

bud16415 03-06-2014 01:31 PM

It’s called a multi wire branch and this link will get you a PDF that explains how they can have a common ground (white) wire. =rja&uact=8&ved=0CDAQFjAE&url=http%3A%2F%2Fwww.hom D7Me4gDiMobi2GxNL6ZY1dW5ndA&sig2=VUkQtiyPZxQ59nChC 0vFZA&bvm=bv.62577051,d.b2I

latelifebiker 03-06-2014 03:27 PM

Bud, you are my Hero of the Month--maybe of the YEAR. You've helped me find and correct a serious electrical situation.
The PDF document you recommended gave a clear and lucid explanation of exactly the question I was asking.
Right after they switched over from sails to steam, I was an electronics technician in the Navy, and as soon as I saw that first illustration in the PDF doc, I grasped the clever use of the phase difference to allow a single return wire. But the article went on to describe the potential for problems and how they occur, as well as how to check for them... which I did.
I'm sure you won't be surprised to learn that BOTH of my multi-wire branches are IMPROPERLY connected. Fortunately, both black and both red wires are long and connected to breakers well down the strip, so I have enough length to reconnect one from each cable to the OTHER side of the box.
This document should be a MUST READ for any DIYer who ever pulls the face panel off a breaker box. Many thanks.

bud16415 03-06-2014 04:23 PM

Glad I could help.

JoeD 03-06-2014 05:42 PM

The other SIDE of the box is not what you want. The legs in a breaker panel are split down each side. They alternate down both sides.
The wires should be connected to two breakers with a handle tie or a double pole breaker so that both of them trip together.
The most important thing is that you have 240 volts between the two hots.

Figure 2 in that PDF looks nice but is not how breaker panels are actually built. Figure 3 represents more accurately how most are built.

kok328 03-06-2014 06:37 PM

This is why I cringe when I hear an electrician say "I will have to pickup a neutral from somewhere" & rarely do you see them poled together in the panel.

bud16415 03-07-2014 06:14 AM

I’m not trying to defend the illustrations in the PDF I linked. It was just one I found that cleared the concept up for me. When I looked at it I saw Fig 2 as a simplified illustration to convey the difference between proper and improper method of splitting the branch. More of the concept.

Fig 3 went on to try and show proper and improper methods in more of a real life setting and then they went on with text comparing a variety of brands in common panels and what to look and or test for if in doubt.

There might be clearer on line tutorials if anyone knows of one please post.

latelifebiker 03-07-2014 10:58 AM


Originally Posted by JoeD (Post 101416)
The other SIDE of the box is not what you want. The legs in a breaker panel are split down each side. They alternate down both sides.

Many thanks, Joe. I will give this situation some thorough study and be sure the connections are correct. I might have been too hasty in passing judgement on the original hookup. I can't believe I didn't recognize that the breakers alternate down the two sides, because it makes basic sense when you notice that the Dryer and the Range (240 connections) are hooked up to ADJACENT breaker slots.

bud16415 03-07-2014 11:42 AM

Chances are you are connected ok. I read your post last night on my phone and thought you most likely would read Joe’s post and get that.

I’m also from the sailing ship days of technology and about a year ago ran into this multi branch stuff and was wondering what was up. I personally haven’t wired any up but I guess it is ok for where you want a couple dedicated circuits close together like the mentioned disposal and dish washer. As a DIY homeowner I buy a roll of wire like 12-2 and it lasts years so for me there isn’t much savings having a roll of 12-3 around. If you are wiring a dozen town houses in a row it could save a lot of time and money.

speedy petey 03-09-2014 07:58 AM


Originally Posted by kok328 (Post 101423)
This is why I cringe when I hear an electrician say "I will have to pickup a neutral from somewhere" & rarely do you see them poled together in the panel.

Thing is, I have NEVER heard a self respecting "electrician" say this.
A handyman perhaps. Carpenter. Even a DIYer.
Never anyone who knew what they were doing.

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