circuit wiring question

Nov 16, 2003 4 Replies

I have a ranch home, built 1952. I'm remodeling the basement and replacing the wiring down there. The basement outlets are powered off a 4 fuse box off the main panel. One fused circuit powers a run of outlets on one wall, another circuit on another wall. What I have discovered is that both circuits appear to be wired to the box with a 3 wire plus ground cable (black, red, white, ground). This wire runs about 20 feet to a junction box where the white is kept common and the black and red run to their respective circuits.



While not what I would like to see, is there anything inherently unsafe about this wiring scheme? Both circuits would be 15 amp. The only concern that I had was that at full load for both circuits, the common return path would have 30 amps (right??) but at almost 0 volts (only voltage due to resistance of the wire itself).



Is there any hidden danger I'm missing? I would really rather not get into the electrical panels if I don't have to (but if it has to be done, I'll have it done).



Thanks in advance, Jed


It is okay if it is done properly; they subtract rather than add. Do a search on multiwire circuit.

But, don't assume it was done properly; one on my house wasn't, or more likely, some clown changed it to make it wrong.

If in fact the two circuits use separate legs of the 220V service, then at full load there is 0 amps in the neutral because the two circuits are 180 degrees out of phase (ignoring phase shift from inductive loads etc.) If they are on the SAME leg, then this is a bad idea--the neutral will be overloaded.

I do read 240V between the "hot" leads. Thanks for the help guys. I'll sleep a little better at night now.

What I have discovered is that both

Jed:

J > I have a ranch home, built 1952. I'm remodeling the basement and replacing J > the wiring down there. The basement outlets are powered off a 4 fuse box J > off the main panel. One fused circuit powers a run of outlets on one wall, J > another circuit on another wall. What I have discovered is that both J > circuits appear to be wired to the box with a 3 wire plus ground cable J > (black, red, white, ground). This wire runs about 20 feet to a junction bo

J > where the white is kept common and the black and red run to their respectiv

J > circuits. J > J > While not what I would like to see, is there anything inherently unsafe J > about this wiring scheme? Both circuits would be 15 amp. The only concern J > that I had was that at full load for both circuits, the common return path J > would have 30 amps (right??) but at almost 0 volts (only voltage due to J > resistance of the wire itself). J > J > Is there any hidden danger I'm missing? I would really rather not get into J > the electrical panels if I don't have to (but if it has to be done, I'll J > have it done).

I haven't seen a response as of the time I'm replying (Sunday mid-evening, though won't upload until early Monday morning). As I understand things if the two hots (black and red) on on different phases then the common neutral (white) is acceptable. A 1 amp load on black 'cancels' out a 1 amp load on the red. The 'cancellation' is due to the phase difference.

- ¯ barry.martinþATþthesafebbs.zeppole.com ®

  • Definition: Hostility -- place for angry guests to stay

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required