I have 2 30-amp circuit breaker in the main panel that is serving ONE outlet 240-Volts that is intended for charging Electric Car?? So the switch is bridged together as one. The outlet is in the garage and I'm not using it right now.

I'm in need of a 2 separate 120 volts circuit. And there is not a lot of room left in the main panel to add additional break. Rather taking those 2 existing breakers and replace it with 2 separate breakers and cabling, I was wonder if I can do this.

Get a portable step-down transformer, something like Powervar, that would plug into the 240 outlet and then step-down the line into 2 separate 120 volts. Then run each of the 120 into the house with outlets to serve the appliance.

1. Is it safe to have the transformer run in the garage? Violation of any electrical code?
2. If this OK, what would be the effective amp/load on each of the 120? It it still 30 or has it been halved?
3. Any other cost effective way?

I figure this is a better approach than rigging the schematic on the main panel. Also the Powervar does line conditioning as well, so that would be a ++ for usag in high-end electronic component. So when I move/sell the house, the circuit is still in tact. I can take the transformer with me.

The Most efficient, cost effective. Cheapest, would be to put in 2 20 amp single pole breakers for the 2 circuits. You would need besides the ground, you would need a neutral.
If it is conduit, Push or pull in another wire for Neutral. 2 circuits can share neutral, if on opposite phase.

I don't have room in the panel. So I have to add a sub-panel... which mean no longer cost effective.

I would use the 2 spaces for the Electric Car. Remove the double 30. Cap wires for future use. They also have 2 120 volt breakers that take up 1 space. 2 could solve your problem,
If you want electric car to remain.

If the outlet is fed by a cable, is it 10-2 or 10-3? If 10-3, you have a neutral and could wire it up as 2 120 circuits with a shared neutral. If the breaker has two handles linked together, you could just remove the link. Otherwise, you would need to buy 2 new breakers.

The transformer plan is fine, as long as it is sized properly, and the neutral that will be created is grounded properly. To power two 20 amp 120 volt circuits, the transformer should be no smaller than 4800 VA. It will need to have a 240 volt input primary, and the output will need to be 120/240 volts to achieve the 2 -20 amp circuits.

The center point , i.e. the neutral, will need to be grounded to a grounding electrode, ie: ground rod or city water, and this connection should be at the same as the main service is grounded.

If the transformer only has 120 volt output, then the circuit will be sized according to the VA output, and not have the two circuits you are seeking.

Then the output of the transformer, before going to far through the branch circuit leaving the transformer, will need overcurrent protection,ie: fuses or circuit breakers.

My point is, simply adding a transformer to change the 30 amp 240 volt circuit to two 20 amp 120 volt circuits is a bit more involved than you may think.


As explained by others, so much easier to remove the 2 pole 30 A Cb, and replace with two 20 amp 1 pole breakers, and convert the 240 volt outlet to the two circuits needed. Of course, this will only work if the 240 volt outlet has two hot wires and a neutral, along with the equipment ground. If the 240 volt outlet is only two hots and ground, then all you can get is one 120 volt circuit.

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Originally Posted by tkrussell

The transformer plan is fine, as long as it is sized properly, and the neutral that will be created is grounded properly. To power two 20 amp 120 volt circuits, the transformer should be no smaller than 4800 VA. It will need to have a 240 volt input primary, and the output will need to be 120/240 volts to acheive the 2 -20 amp circuits.

The center point , ie the neutral, will need to be grounded to a grounding electrode, ie: ground rod or city water, and this connection should be at the same as the main service is grounded.

If the transformer only has 120 volt output, then the circuit will be sized according to the VA output, and not have the two circuits you are seeking.

Then the output of the transformer, before going to far thru the branch circuit leaving the transformer, will need overcurrent protection,ie: fuses or circuit breakers.

My point is, simply adding a transformer to change the 30 amp 240 volt circuit to two 20 amp 120 volt circuits is a bit more involved than you may think.


As explained by others, so much easier to remove the 2 pole 30 A Cb, and replace with two 20 amp 1 pole breakers, and convert the 240 volt outlet to the two circuits needed. Of course, this will only work if the 240 volt outlet has two hot wires and a neutral, along with the equipment ground. If the 240 volt outlet is only two hots and ground, then all you can get is one 120 volt circuit.

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Thank you for your input. The reason why I'm leaning toward this approach is preferring the Powervar unit is because it has the conditioning -- this will save me to get additional power conditioner.

The outlet that provide the 240 has 4 prongs--I have tested it with volt meter. With 2 side prong gives a reading of 238 V. With either side and common neutral gives a reading of 118V. So that means that the top prong is the ground... which mean I have there are all the necessary cables I need.

The Powervar that I was looking at have a kVA 5.0 rating. So it is inline with what you suggested.

Thanks again for all the input.

OK, seems you have the proper input for 120/240, and I understand the power conditioning issue, and seems you understand the connection. Just want to reiterate about the neutral. Once a transformer is used to create 120 volts for a building, this becomes a separately derived system, the neutral will need to be grounded. This is an important issue, just want to be sure you understand this needs to be done. If you are unsure about this, please get back with your questions.

Quote:

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Originally Posted by tkrussell

Just want to reiterate about the neutral. Once a transformer is used to create 120 volts for a building, this becomes a separately derived system, the neutral will need to be grounded. This is an important issue, just want to be sure you understand this needs to be done. if you are unsure about this, please get back with your questions.

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Your concern/opinion is invaluable. So I want to understand this further.
The transformer(tx) has 2 separate legs of output receptacles... each being 120V. Each leg will have 3 cable (hot, neutral, ground). These are all provided by the tx. So my plan was just to take each of the leg and cable/mount it to standard wall outlet. I may have powerstripper from that outlet use as distribution across various components.
So would this be sufficient? Or you saying that the neutral that is coming out of the tx must be grounded back the main ground even the input to the tx is already grounded from the 240 outlet? May be I'm missing something else?

Thanks.

If the transformer input will use the neutral of the outlet, which I doubt, then the 120 volt output neutral will be grounded through the system neutral.

I suspect the transformer will only accept 240 volts along with the equipment ground. If this is true, then the neutral of the output will be created, and will not be "neutral" until it is grounded.

Do not get confused with the equipment ground at the outlet, and grounding the neutral, or that the case of the transformer is grounded.

Once a neutral is created, it will only be a true neutral once it is grounded, and this means connection to a grounding electrode, such as a ground rod.

This may help, or may add to the confusion, If I ddi not help you understand do not heistate to ask more questions.

See, I told you changing the breaker would be easier.

If you really need conditioning, you can get a separate unit for that, such as a UPS.