Sub Panel Install
#1
09-09-14, 06:57 PM
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Sub Panel Install
I hope someone can help me answer some questions. I have been doing a lot of research about this but I just want to make sure I have everything correct. I had a 50amp circuit that ran from my main panel to a receptacle 50’ away in a detached garage. The wire that was used is a 6/3 feed to a NEMA 5-50R receptacle. The 3-wire cable connected the receptacle to the neutral bus and the Breaker. The black and white wires were attached to the breaker and the green was attached to the neutral bus. I had an electrician come in and tell me he could use the existing cable to wire the sub panel since the sub panel would only service two 220V circuits. One circuit is used for a dryer and the other for an air compressor. He’s telling me that a 4 wire feed is needed if the sub panel services 120V circuits but only a 3 wire feed is needed if the sub panel only services 220V circuits. Is this true and is this safe? Current configuration is attached as a photo.
#2
09-09-14, 07:03 PM
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The dryer is a 120/240 load.
Sub panels in the same building as the serice need to have 4 wire feeders.
Sub panels in the same building as the serice need to have 4 wire feeders.
#3
09-09-14, 07:26 PM
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PC, not all clothes dryers are 240/120, mine is straight 240.
Fred, do you have ANY 120 volt loads in the DETACHED garage? There are only six exceptions that allow multiple sources of power to a building and most of them do not apply in a residential situation. That stated, the connection of the WHITE wire to the circuit breaker or the receptacle is wrong, the wire color must be changed to something other than white, grey or green to meet code requirements.
What insulation type is this 240 volt cable? How is it run to the garage? Only certain types of cable may be used outdoors or be buried.
The NEC changed the rule, back in 2008 I believe, that allowed three-wire feeders to outbuildings. It IS possible that your installation is acceptable IF you have no other metallic connections between the buildings such as a water pipe or ANY other electrical wiring AND your LOCAL code (the only code that matters) has not been updated or specifically allows a three-wire feeder.
Post back.
Fred, do you have ANY 120 volt loads in the DETACHED garage? There are only six exceptions that allow multiple sources of power to a building and most of them do not apply in a residential situation. That stated, the connection of the WHITE wire to the circuit breaker or the receptacle is wrong, the wire color must be changed to something other than white, grey or green to meet code requirements.
What insulation type is this 240 volt cable? How is it run to the garage? Only certain types of cable may be used outdoors or be buried.
The NEC changed the rule, back in 2008 I believe, that allowed three-wire feeders to outbuildings. It IS possible that your installation is acceptable IF you have no other metallic connections between the buildings such as a water pipe or ANY other electrical wiring AND your LOCAL code (the only code that matters) has not been updated or specifically allows a three-wire feeder.
Post back.
#4
09-09-14, 07:36 PM
The wire that was used is a 6/3 feed to a NEMA 5-50R receptacle. The 3-wire cable connected the receptacle to the neutral bus and the Breaker.
5-50R receptacle
#6
09-09-14, 09:15 PM
Oops, you were posting as I was writing. I almost brought that point up too but the 240 are not that common and I was writing using the KISS method. He said he had a 5-50r receptacle which if it wasn't a typo and was used as intended is a 120 volt receptacle.
#8
09-10-14, 07:55 AM
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The dryer is a straight 240 volt unit. There will be no 120V circuits in the sub panel. The feeder that connects the 2 structures is a direct burial cable so there is no conduit connecting the 2 boxes.
#11
09-10-14, 08:11 AM
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There are two direct feeds that run from the main panel to the structure. One is a 120V circuit that controls the lights and then there is an additional circuit that has a Nema 5-50R receptical on it. That's the circuit that's in question here.
#12
09-10-14, 08:14 AM
There is a separate circuit for light already.
#13
09-10-14, 10:10 AM
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Thanks for the information Ray I really appreciate it. I will make sure I have him run the correct cable. Although for my own knowledge if there had been no light circuit at all involved would it have been safe to just have a three wire cable to the sub for just the 240V circuits.
#14
09-10-14, 11:32 AM
Three wire is misleading. The correct term is 2-conductor cable (ground isn't counted for building cables so the 6-3 in the diagram is wrong. You have 6-2) If the light cable had been disconnected on both ends and cut too short to be reconnected then the two conductor cable would have been compliant assuming it is UF not NM and buried at least 24".
You may want to consider installing a 60 amp feed to a 100 amp 12 space main breaker panel. This will give you plenty of room for breakers and a little head room on amps for lights and receptacles and maybe a larger welder.
Two puzzles remain though not important at this point. You wrote:
The ground in UF is bare. Was that a typo? You wrote the receptacle was a 5-50, a 120 volt receptacle, but you had 240 volts to it.
You may want to consider installing a 60 amp feed to a 100 amp 12 space main breaker panel. This will give you plenty of room for breakers and a little head room on amps for lights and receptacles and maybe a larger welder.
Two puzzles remain though not important at this point. You wrote:
and the green was attached to the neutral bus.
Last edited by ray2047; 09-10-14 at 05:55 PM.
#15
09-10-14, 06:13 PM
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Yes they were both typo's the receptacle is a 6-50R 250V and the UF cable has a bare copper not a green cable. So to reiterate it's ok to have a 3 wire feeder as long as there is no other feeds run to the structure and no 120V circuits. White and Black to the hot lugs of the sub panel and the bare to the Neutral bus. No neutral bond to the case. Then connect the sub circuits where the black and white go to the breakers and the bare goes to neutral bus. No need for additional ground since this will only house 220V circuits. Correct?
#16
09-10-14, 06:23 PM
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No need for additional ground since this will only house 220V circuits. Correct?
#17
09-10-14, 06:34 PM
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Its a Whirlpool WED5550YW. When i mentioned ground i was referring to a separate ground bus in the sub panel. Why would i need ground rod as this is handled by the main panel.
#18
09-10-14, 06:50 PM
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Why would i need ground rod as this is handled by the main panel.
When i mentioned ground i was referring to a separate ground bus in the sub panel.
I don't know for sure if it matters in this case, but I am also not sure your dryer will work correctly on 60 hz power.
Whirlpool WED5550YW High Efficiency Cabrio Dryer
The Whirlpool WED5550YW was built for 220/240 volt 50 hertz market!
The Whirlpool WED5550YW was built for 220/240 volt 50 hertz market!
Last edited by CasualJoe; 09-10-14 at 07:06 PM.
#19
09-10-14, 07:19 PM
So to reiterate it's ok to have a 3 wire feeder as long as there is no other feeds run to the structure and no 120V circuits.
#20
09-10-14, 07:50 PM
Interesting from Whirlpool WED5550YW High Efficiency Cabrio Dryer 220 volt | Multisyste
I wonder if it will smoke or do something else odd?
The Whirlpool WED5550YW was built for 220/240 volt 50 hertz market!
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Voltage: 220-240 Volts / 50 Hertz
This appliance is not designed for use in America. Only for countries that use 220 / 240 V electrical outlets.
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Voltage: 220-240 Volts / 50 Hertz
This appliance is not designed for use in America. Only for countries that use 220 / 240 V electrical outlets.
#22
09-10-14, 08:25 PM
Fred, you really need to reconsider what you are doing. Nothing is really correct not the dryer or the planed power supply to the garage.
Last edited by ray2047; 09-10-14 at 08:47 PM.
