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Old 11-25-2012, 02:17 PM   #1
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Help with new 220V sub panel circuit


Greetings. I've done quite a bit of 110 wiring and some 220 but I'm a bit weak in that area. I've got a new 60 gallon 220V air compressor that is now located in my garage approximately 50 feet from the house which is where the main breaker panel is located. There is no room to add another 220 breaker or in any way add an additional separate circuit without adding a sub panel. I've purchased a two pole 30 amp breaker and matching sub panel and need to wire it into the existing main breaker panel. Most 220 circuits I've seen previously are either 3 or 4 wire configurations however the motor for my compressor is a 2 wire plus a ground setup. I've run the appropriate length of 10/2 outdoor NM wire from the compressor to the location where the sub panel will be installed. What I need to know is the connections that need to be made. There was previously a hot tub 220 circuit but it was removed when the hot tub was relocated to my sisters house however on each leg coming in from the meter there is a copper lug with a set screw that look to have been added and are not used by any other circuit. I think possibly this is where the hot tub wiring was connected but am by no means certain. What I really need to know is, since I need 220 but will have no third wire for a neutral, and I know this is how it needs to be and have read a good deal about this type of connection but can find no schematics or specific connection instructions, do I simply hook one wire from each incoming leg to each of the breaker connectors in the sub panel, and then do the same on the opposite side of the breaker using the wiring that runs out to the compressor, and just not use a neutral at all, and connect my bare ground wire to the neutral bus in the main breaker panel? Any help, additional information or diagrams will be appreciated. Comments to the effect that you can't run 220 without at least 3 wires plus a ground wire, will not, as I already know that's untrue.Here's what I'm assuming I need to do. Please feel free to correct any incorrect assumptions if I'm wrong. Thanks.
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Old 11-25-2012, 02:30 PM   #2
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Help with new 220V sub panel circuit


A. What is the model number of that GE load center? What amperage?
B. What is the required ampacity of the compressor.
C. It is unlikely the compressor needs a neutral.
D. Those lugs are a modification not intended or listed by the manufacturer.

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Old 11-25-2012, 02:38 PM   #3
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Help with new 220V sub panel circuit


No!!!! That is totally illegal there. i know here in my area of SC that is totally not permitted... You will also need that neutral wire as well the ground.

Do you have a 200 amp combo on the outside of your house you can tie into?
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Old 11-25-2012, 02:38 PM   #4
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Help with new 220V sub panel circuit


section 250.142(B) of the 2011 NEC covers bonding and grounding in sub panels you MUST run 4 conductors, 2 hots, neutral, and ground, and the neutral and ground must not be bonded together in the sub panel.

Whoever told you that you only have to run 3 conductors is just flat out wrong.

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Old 11-25-2012, 02:43 PM   #5
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Help with new 220V sub panel circuit


Yeah, I realize the lugs are modifications. As I said, they were used, I believe, for the circuit that fed the hot tub pump that was previously installed but no longer is. It worked fine for years. I know that doesn't mean it was correct per code but I just want this to work for now, not worried about it being a licensed installation or being able to pass an inspection. This will be a temporary situation until I can install a bigger main panel. The sub is an Eaton outdoor 70 amp main lug unit. Model is BR24L70RP. The compressor is a 15 amp. The breaker I have is a 30 amp. The compressor has no place on the pressure switch for a neutral wire, nor does the diagram on the pressure switch or motor indicate one.
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Old 11-25-2012, 02:46 PM   #6
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Help with new 220V sub panel circuit


HOWEVER AS AN OPTION::: it is acceptable(allowed) to where you can swap out two single 20 amps breakers replacing with a duplex 20 amp breaker.

Then you will have the required space for the 30 amp dbl brkr.

ALL depending on the existing service with a 100 amp or 200 amp? 200 amp.. yes!
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Old 11-25-2012, 02:46 PM   #7
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Help with new 220V sub panel circuit


Quote:
Originally Posted by darkbreeze View Post
The compressor has no place on the pressure switch for a neutral wire, nor does the diagram on the pressure switch or motor indicate one.
Understood, but you still need to run one to the sub panel per the NEC, not my rule...

Also, you need to feed the panel with a double pole breaker in the main panel. Feeding it from lugs on the bus bar is not acceptable.

Think about it, you are protecting # 10 wire with the 100 or 200 amp main breaker in your panel. If something goes wrong, that sucker ain't gonna trip!

It would be like connecting 14-2 romex to a 50 amp breaker.

Very bad idea, and totally in violation of code, not to mention basic electrical safety.

Last edited by TTW; 11-25-2012 at 02:51 PM.
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Old 11-25-2012, 02:48 PM   #8
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Help with new 220V sub panel circuit


Really, where would I connect them to as there is no place on the pressure switch for anything other than the two hots to be connected. This is a hardwired installation so there is no receptacle. Do I just need a neutral to the bus inside the sub panel? Seems redundant as the ground bus and neutral bus are connected in the main panel and the bus in the subpanel is already going to be connected to it via the ground. Not argueing, just asking.
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Old 11-25-2012, 02:49 PM   #9
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Help with new 220V sub panel circuit


Quote:
Originally Posted by JuzRick View Post
No!!!! That is totally illegal there. i know here in my area of SC that is totally not permitted... You will also need that neutral wire as well the ground.

Do you have a 200 amp combo on the outside of your house you can tie into?
What do you consider an A/C disconnect? It is totally permissable to install a panel for 240 volt loads only. No neutral required.
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Old 11-25-2012, 02:50 PM   #10
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Help with new 220V sub panel circuit


Quote:
Originally Posted by darkbreeze View Post
Yeah, I realize the lugs are modifications. As I said, they were used, I believe, for the circuit that fed the hot tub pump that was previously installed but no longer is. It worked fine for years. I know that doesn't mean it was correct per code but I just want this to work for now, not worried about it being a licensed installation or being able to pass an inspection. This will be a temporary situation until I can install a bigger main panel. The sub is an Eaton outdoor 70 amp main lug unit. Model is BR24L70RP. The compressor is a 15 amp. The breaker I have is a 30 amp. The compressor has no place on the pressure switch for a neutral wire, nor does the diagram on the pressure switch or motor indicate one.
What is the model number of your MAIN panel? It should be a TMxxx or a TLMxxx.
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Old 11-25-2012, 02:51 PM   #11
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Help with new 220V sub panel circuit


Can't swap out any breakers as they are all needed for the house and existing circuits.
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Old 11-25-2012, 02:53 PM   #12
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Help with new 220V sub panel circuit


Quote:
Originally Posted by darkbreeze View Post
Can't swap out any breakers as they are all needed for the house and existing circuits.
What is the model number of the main panel?
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Old 11-25-2012, 02:54 PM   #13
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Help with new 220V sub panel circuit


TLM1212RCU on the main panel.
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Old 11-25-2012, 02:55 PM   #14
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Help with new 220V sub panel circuit


Quote:
Originally Posted by darkbreeze View Post
Really, where would I connect them to as there is no place on the pressure switch for anything other than the two hots to be connected. This is a hardwired installation so there is no receptacle. Do I just need a neutral to the bus inside the sub panel? Seems redundant as the ground bus and neutral bus are connected in the main panel and the bus in the subpanel is already going to be connected to it via the ground. Not argueing, just asking.
The sub panel neutral and ground CANNOT be bonded/connected in the sub panel. This is a major no-no.

Please look at the picture I sent earlier.
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Old 11-25-2012, 03:00 PM   #15
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Help with new 220V sub panel circuit


Ok, so there are two bus bars in the sub panel. So as long as I run a neutral to the neutral bus in the sub, and a ground to the ground bus in the sub, I do not need to run any neutral wires from the sub out to the compressor, correct? Thanks

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