2 breakers for one conductor

[Denray]

Going thru some old photos I found this. (2) 20 amp wafers going to one stranded conductor. If the strands are evenly split will that put out 40amps? I'm sure it's not correct. What will be the problems?

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[Richard Moore]

All things being roughly equal, yes, 40 amps. You are splitting the load between the two breakers. At 40(+) amps, one breaker will trip followed very, very quickly by the other. All things being exactly equal, then I guess both could trip simultaneously.

But, you just can't do that! Among many other questions; Assuming this is part of a 240-volt, 40-amp circuit, where the hell is the other leg?

Oh...and whats a "20-amp wafer"? I've never heard that term.

[Denray]

Are'nt those two skinny breakers that the conductor is split between called "wafer breakers, piggy back, half-width, or twin breakers? That's the way they are discribed in Mr. Hansens book.

Yep, I don't know where it went to. Maybe it wasn't for a 240 circuit.

Thanks for the reply Richard.

[Richard Moore]

Hmmm....I've never heard them described as wafers before. But, it might just be me(?).

[John Kogel]

I could be wrong, but I think the thin, tandem or wafer breakers ride on the same bus. So you can't get 240 volts that way.

A load exceeding 20 amps will trip at least one of those breakers. I think.

So it is a 20 amp circuit.

[David Meiland]

Wouldn't that make it a 40A 120V circuit?

[Marc]

It's a wiring error.

Marc

[Richard Moore]

I could be wrong, but I think the thin, tandem or wafer breakers ride on the same bus. So you can't get 240 volts that way.

A load exceeding 20 amps will trip at least one of those breakers. I think.

So it is a 20 amp circuit.

The twin, tandem, 2 wafer breaker, whatever, is in a single, full size slot and therefore on a single bus bar tab so, yes, it's all the same 120-volt leg.

But, no, the load does get split between the breakers. There's probably going to be some unevenness, so you might not get a full 40-amps before one of them trips at 20, but it will be a lot closer to 40 than 20.

Some (Siemens for example) 200-amp main breakers are actually four 100-amp breakers tied together as two pairs. Same thing, 2 x 100 = 200.

My best guess (because, offhand, I can't think of any other sane reason for doing it) would be a change from an electric range to gas and they moved one leg of the original 240-volt feed to provide a 120 receptacle for the new range. Trouble is, the way it's hooked up, that 20-amp receptacle is way overfused. Maybe they too thought it would be 20-amps that way, but they were wrong.

[Denray]

Nice wrap up Richard. My 82 yr old mech engineer Dad got just about that far too.

[John Kogel]

Thanks, Richard. That question could have kept me awake last night, but, nah, I let it go.

That's a good guess about the electric to gas conversion. They should have attached a smaller gauge jumper to the feeder with a wire nut, then an easy connection to one terminal.

Flip one of those handles to 'off', and you'd have a simple 20 amp circuit.

So, what happens to the electrical charges that were riding on those strands that are now disconnected? They jump to the other side. Where do they start jumping? At the breaker, at the outlet or somewhere in between? []