what a mess ! (nightmare electrical situation at old house)

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junkhound said:
LOL ... Own house is 50 YO this year with QO breakers.

do I need to replace those with 'modern' homeline breakers? :rolleyes:
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QO & type CH were fairly new then, replacing XO, 1959-60 seem to be the death throws for XO based on dates on equipment or date of construction.
 
norcal said:
QO & type CH were fairly new then, replacing XO, 1959-60 seem to be the death throws for XO based on dates on equipment or date of construction.
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I believe QO was introduced around 1957, so that time frame is probably right. You could get XO breakers from Square D into the early 70s but by the late 70s even Cutler Hammer had stopped offering them.
 
jim dungar said:
I believe QO was introduced around 1957, so that time frame is probably right. You could get XO breakers from Square D into the early 70s but by the late 70s even Cutler Hammer had stopped offering them.
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I bought a SQ D XO120 for $8 back in the seventies, huge money then. Was told at the supply house that SQ D tooled up once a year to make them, if my memory serves me there was no listing for them either.
 
There are 13 single-pole breakers on the right side; there are 5 single-pole breakers on the left side, along with 4 double-pole ones. Indeed, the black wires (hots to the breakers) along the right side are all in phase, as are the red ones. Same is true on the 5 on the left side; but the phases are reversed, the blacks on the left side being out of phase (i.e. 240vac measured between them) with the blacks on the right side (and same for the reds). Might be ok. Might not be. Hard to tell, since the sheaths are gone.

I suppose there are tricks I can do to try to identify MWBC pairs (and their corresponding neutral). Turn on everything in the house. Turn off all the breakers - except one. Use clamp-on ammeter to find the corresponding neutral that has current on it and label the wire with tape (1N or something), Label the hot leg as 1A. Rinse and repeat ... If another breaker causes current on the same neutral, that's the other side of the MWBC.
 
Forgive my impolite belly laughter, but I'm envisioning a plumber called in to diagnose #5.

zbang said:
When did 35 years become an "old house"? :D
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When it has a lot of old wiring that needs work. :(

RustyShackleford said:
Not quite following. Yes, that's a good way to tell if an outlet in energized ... But how to get from there to grouping the wires ?
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Use a flasher, a large incandescent lamp, and a clamp-on ammeter.
 
drcampbell said:
Forgive my impolite belly laughter, but I'm envisioning a plumber called in to diagnose #5.
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Well, evidently the home inspector did flag the water heater as not working. Fortunately, for the owners, they didn't call a plumber before I figured this out. The screwy wiring was probably not done by the original electrician, but by the plumber who installed the tankless unit. I simply deleted one of the two 3-way switches and capped off one of the travelers (at both ends) and the other traveler became a hot.
drcampbell said:
Use a flasher, a large incandescent lamp, and a clamp-on ammeter.
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Still not following ... Yeah, I get I'll use a clamp-on ammeter. Turn on one (and only one) of the breakers and see current flowing; see which neutral also has current flowing (with the same ammeter). Later on, when one of the other breakers produces current in the same neutral, I know it's the other side of the MWBC. Still not sure what the flasher does ...
 
"Young whipper snappers" :)
During my apprenticeship, I helped change out "MO" breaker panels.
Most interesting when you needed to check for power on the load side.
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LarryFine said:
Think of it as a turn-signal flasher for 120v.
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I get that it helps you tell if a circuit (or receptacle) is energized, from a distance. I still don't see how that helps in grouping the 3 conductors (neutral and hopefully-opposite phase hots) in an MWBC. At least if you do it by the method I described above in post #26. Maybe there's a better method ?
 
RustyShackleford said:
I get that it helps you tell if a circuit (or receptacle) is energized, from a distance. I still don't see how that helps in grouping the 3 conductors (neutral and hopefully-opposite phase hots) in an MWBC. At least if you do it by the method I described above in post #26. Maybe there's a better method ?
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It works best with a analog clamp on meter, as the lamp flashes you will see the needle move slightly.
 
norcal said:
It works best with a analog clamp on meter, as the lamp flashes you will see the needle move slightly.
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Use a 250-watt bulb. The needle will dance up & down over a 2-amp range. You won't have any difficulty seeing that on a 15- or 20-amp circuit.

It's a less-invasive technique; there's no need to turn anything off.
 
drcampbell said:
Use a 250-watt bulb. The needle will dance up & down over a 2-amp range. You won't have any difficulty seeing that on a 15- or 20-amp circuit.
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So I see pulsating current on the neutral, got it. Ah well, it seems to be unavailable. One of those "toner" widgets should do it though.
 
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