Effective Two-Pole Breaker Rating?

[HRTKD]

I have a two-pole breaker that is rated for 20 amps on each breaker. At the outlet, is that a 40 amp circuit? Or is it a 20 amp circuit?

This question is not related to PV. It's for an outlet in my garage. No PV/battery/inverter in my house.

 

[jwelter99]

2 pole breaker is typically used for 240V and each "leg" is 20A. They are typically ganged.

If above is correct, from each hot you have a 20A breaker to neutral. You have a total of 240V @ 20A.

 

[HRTKD]

Yes, the two breakers are ganged. So is that a 20 amp circuit or a 40 amp circuit? I'm thinking it's 20, but wanted to be sure.

 

[Whinny]

It's a 20a circuit, can be wired as two 120 or one 240v , do the breakers have a tie bar? If not it's typically two 120v.....might have to pull the cover to check.

I type too slow.....

edit...........20a 240v

 

[jwelter99]

Yes, the two breakers are ganged. So is that a 20 amp circuit or a 40 amp circuit? I'm thinking it's 20, but wanted to be sure.

240V 20A. Each "hot" leg is 120V and 20A, to give you a total of 240V at 20A.

 

[HRTKD]

OK. Thanks for the confirmations. I've got significant re-wiring to do. My electrician (20 years ago) did a minimal install that isn't going to support what I need. Too long of a run, too small wire, too small breaker.

 

[Whinny]

Brain just went clunk.....
Do you have 20a plugs in the house? It could be a 3 wire feeding outlets at 120.....not really sure of your code.

 

[HRTKD]

This is in the garage. I have two hots going to the outlet, no neutral, ground is picked up from outlet box. Conduit from the subpanel to the outlet.

 

[jwelter99]

OK. Thanks for the confirmations. I've got significant re-wiring to do. My electrician (20 years ago) did a minimal install that isn't going to support what I need. Too long of a run, too small wire, too small breaker.

Just be aware lots of code changes and by touching it you might have to update to latest code depending on local regs. You may choose to ignore this, but then can have insurance issues if ever a electrical fire.

Old poorly done electrical is a PITA as not easy to fix it without it becoming a all-or-nothing type job.

 

[HRTKD]

Just be aware lots of code changes and by touching it you might have to update to latest code depending on local regs. You may choose to ignore this, but then can have insurance issues if ever a electrical fire.

Old poorly done electrical is a PITA as not easy to fix it without it becoming a all-or-nothing type job.

Yeah, this is a situation where, for this particular circuit, I may need to start over all the way from the main panel. What I have is enough for a 220v table saw, but not the new EV charger or my welder. I think what will happen is the existing circuit will be left alone and a new circuit gets created.

 

[jwelter99]

Yeah, this is a situation where, for this particular circuit, I may need to start over all the way from the main panel. What I have is enough for a 220v table saw, but not the new EV charger or my welder. I think what will happen is the existing circuit will be left alone and a new circuit gets created.

It maybe easier to put a sub-panel in the garage. That way you have flexibility in the garage as needed, up to the amperage of the tie back to the main panel.

 

[Ampster]

Yes, I would consider a sub panel. It could save you some money on wire and reduce voltage drop.

 

[HRTKD]

I already have a subpanel. It's in the basement, real close to the garage. All the current garage circuits come off of the subpanel. I don't think the wire to the subpanel is big enough to support the new circuit I need. The circuit breaker from the main to the subpanel is a 70 amp double pole (70, each side). The wires from the panel to the subpanel are big, maybe just not big enough. I can't find a gauge printed on the wire.

 

[Ampster]

Okay, that subpanel should work. Is it safe to assume your previous installer put it the correct breaker to protect whatever wire he used? Some wire size tables give the diameter of the wire. I would expect to see at least 4 AWG for a subpanel fed by a 70 Amp breaker. Is it copper or Aluminum?

 

[HRTKD]

I think the subpanel is maxed out for the current circuits, or very close to it. Hence the need for the new circuit in the garage to come all the way from the main panel.

 

[Ampster]

I think the subpanel is maxed

Maxed out in terms of breaker slots or maxed out in terms of capacity or load calcs?

 

[HRTKD]

Maxed out in terms of breaker slots or maxed out in terms of capacity or load calcs?

There are breaker spots open in the subpanel. However, I think the circuits in the subpanel have maxed out the wiring between the main panel and subpanel. If I count up the number of amps of circuit breakers in the subpanel, it's more than the circuit breaker in the main panel that feeds the subpanel. 140 amps in the main panel (two-pole circuit breaker, 70 amps on each side), 170 amps in the subpanel. Maybe that's acceptable? I don't know what code allows but that difference is a yellow flag to me.

 

[Ampster]

Maybe that's acceptable?

I think that is the purpose of load calcs, to determine what circuits could be on and how much they could be drawing. Typically you are probably not going to run your 240 volt table saw, and your welder at the same time. An EV charger might be considered differently because it is a constant load but on the other hand mine typically runs late at night. If you are using the same outlet for all three that could solve that problem. I just installed a device at my ex wife's house that allows her to charge her car from the dryer outlet and not have to add a circuit. The two ones I looked at were Dryer Buddy and NeoCharge.

 

[Ampster]

I would add that you should try to disconnect the DC at the breaker or Inverter first, because if it is just a loose connection, reconnecting under the load of the inverter could result in a spark that could damage that connection. I did not read enough of the thread to find out if the system was always working or if someone may have originally connected under load, and might have damaged a connection that ultimately failed.