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Will, President & Small Business Owner
Category: Electrical
Satisfied Customers: 342
Experience:  IBEW apprentice to Journeyman, 30 years experience Owner Operator
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# I have a 240 volt system for pool motor and pool sweep. In

Dennett Hanssmann [email protected]

Will :

You asked a great question with very complete details,

Will :

you can't use 2 single pole GFCI CB's on a MWBC which is sharing a neutral. You certainly could use a 3-wire circuit with a 2 pole GFCI CB

Will :

When a GFCI is protecting a simple 120 volt circuit it monitors the current on the neutral and the hot as long as they are within about 5ma the GFCI will not trip.

When a GFCI is protecting a 240 volt circuit it monitors the current on both hots, as long as they are within about 5ma the GFCI will not trip.

When a GFCI is protecting a 120/240 volt circuit it monitors the current on the neutral and the two hots as long as they are within about 5ma the GFCI will not trip.

Will :

You seem to be very educated in electrical, you do need a 2 pole breaker, this is a hot topic many times over, so don't feel like your question or decision was out there, many argue over this question especially about differentials {if that would happen to be the case between the two poles if configuration of 120 volt loads were needed, and around a pool you want the best, XXXXX XXXXX to be double correct, pardon the pun, but since you can return the two for the one, should be no problem

Customer :

What is a mwbc?

Customer :

Oh, I bet it is multi-wire branch circuit?

Customer :

I gather that a 120V circuit is just one side, one or the other of the hot wires separated by 240V from each other, and by 120V from neutral. And, I gather that a 240V circuit is one that is just using the two hot wires to make the total 240V difference. But, what is a 120/240V circuit?

Will :

## Multiwire branch circuit definition & implementation

I am running a MWBC to an outbuilding. I want to qualify for Exception to 250.32, which allows NOT having a grounding electrode for the out-building provided it is a single branch circuit feeder (including MWBC). The supply is a 240v 3-conductor 10 awg, if it matters. There will be a cut-off switch at the outbuilding.

As for the actual circuitry within the outbuilding, I am wondering what the pros/cons are for running several 2-wire conductors from the cut-off switch (some on each hot wire --- i.e. some run from black feed, some from red feed) versus running 3-wire conductors to everything in the outbuilding.

It seems easier to me to run 2-wire from the switch as outlined above and divide the load that way. But, does that still constitute a MWBC from the perspective of the250.32 exception? (There is no fusing or circuit breakers in the outbuilding.) Is this acceptable? desirable? frowned upon?

Will :

this is one example of the confusion

Will :

and yes you are correct again,

Will :

To have both 120 and 240 volts at the shed or other separate building [whatever the situation] you must run one combination 120/240 volt circuit aka multiwire branch circuit. (It has two hots, one shared neutral, and one ground).

To have more than 20 amps of 240 volts or more than two 20 amp subcircuits of 120 volts you must have a subpanel out in the shed.

Will :

The problem comes from different interpretations of the NEC and too many DIY electrical problems, few know what you know, but run wire and plug things in all day, I also volunteer on allexperts.com and have for years, it is a wonder thousands don't burn buildings down each day, it is refreshing to hear from someone who actually asks intelligent questions you must have some kind of training,

Will :

I have another guy who just lost his reverse switch for his boat hoist but wants to direct wire the motor to get the boat out for visitors I have not heard from him in a while I told him to take the load off the motor, how to wire it, and now worry he is in between a boat and a hard spot,

Customer :

Okay, you may be getting a little beyond me. I have 2 motors, I think about 1hp each, and they would constitute almost all of the load for the subpanel. There are #10 in a 4 wire feeder from the service, and I'm presuming, then, I will wire with a ganged breaker, gfci, to these motors [via timers that control them]. So, is the ganged breaker labelled 240? (Not 120?) And, I'm presuming that the full load from the 2 motors, at 240V, should make 20A sufficient protection for the breaker rating? Yes, I used Richter's book years ago, and got a lot of help from LA County Building Inspection Dept. when re-wiring a house woefully under code, as the homeowner. Years of hobby of electrical stuff before that. But obviously my knowledge is spotty, and I don't want to screw this up. Is any of this wrong. Oh, there is an unbalanced load on the whole system at the subpanel, i.e. there's a 120V pool light, but that is upstream from the 240 gfci ganged breaker, and is a separate 120V gfci which will serve the pool light. So, I think if you just answer this last inquiry, esp. as to the ratings for the 240V circuit and it's breaker(s), that should do it. I think my account has \$45 in it, and I'll be happy to pay you that in entirety if, either now, or later, I see my way clear to a well-done job from your responses. Thanks so far.

Customer :

Reviewing the above, there should be a question mark after "Is any of this wrong(?)", and the pool light circuit isn't exactly "upstream" of the 240V 2 pole breaker, just on one of the same busses, as one side, and neutral on the other. So, from your description of how the gfci works, each breaker will be monitoring it's own imbalance, and there won't be any effect from the pool light drawing current from only one of the hot feeders.

Customer :

So, just to summarize my only further questions, I THINK!: 20A okay for the ganged breaker supplying at 240 V two 1hp motors? I can get the VA and current ratings on those motors, I think, from the nameplates, but I presume the hp ratings are enough for you. And, is the 240 the nominal rating, i.e. not 2 120 "sides" for the ganged breaker for those motors?

Customer :

I'm getting a bit tired, and may need to check out for now. Thanks for your help so far, and I'll check again in the morning if I don't stay present for your last response tonight. Is there a way to get back to you in case I want to pose further questions? Thanks for the help so far. I think I'd like to press "accept" so you are sure to be paid, but I'm still hoping for those last answers. I'll wait a few more moments, then hope to re-check here in the A.M. I'll press "accept" before I leave.

Will :

Will :

with a pool in my area and I have one, a 5 foot fence is demanded by my insurance, a 6 foot fence is not allowed as injury is more likely climbing a 6 foot fence versus a 5 foot, go figure

Customer :

I have a permit, and the thing will definitely be inspected before it is put to use. But these were the ratings on the previous breakers, and they virtually never tripped. They were not, except for the light, gfci, so this is an upgrade to the system. I'll ask the inspector(s) and be sure they're comfortable with it. If there's any question, I'll hire an electrician, which was what I had hoped to do online, but I understand your hesitation. Thanks, XXXXX XXXXX been very helpful.

Customer :

May I pay you, now?

Will :

You are welcome and great to hear you have the perfect plan, I think you are going to be just fine with those ratings, but virtually never tripped means what?

Customer :

Just that the ratings must have been reasonably generous and not too close to the actual current drawn by these motors. And the breakers that were in there were 20A.

Customer :

I do appreciate you efforts. Must go to bed. Let me know when I can press "accept" and I'll do it tonight, or, if I have to check out, I'll re-visit for that purpose in the next day or two, same spot online.

Will, President & Small Business Owner
Category: Electrical
Satisfied Customers: 342
Experience: IBEW apprentice to Journeyman, 30 years experience Owner Operator
Customer: replied 5 years ago.
Will,

You DO understand my circuit. So, the question I'm still asking is simply this: IS the breaker I want, regardless of amperage rating, a 240V, 2 pole (double breaker with handles tied together)? The puzzlement comes, I think, because, right or wrong, the OLD circuit just had two independent breakers, one on each hot side, and if either breaker were to trip, the circuit would be opened. And I think they may have been 120V each. They were NOT gfci, so there was no question about monitoring between a neutral and a hot vs. two hots. So, 240, 2 pole breaker? Thanks in advance.

Dennett H.

Hello .. yes you need a 2 pole breaker

is there a separate breaker for each motor? and one for the lights .. in that sub panel ??

please could you look on the name plates of the motors and post the amperage rating gs of each here .. Thanks