Sub Panel Install

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  #1  
Old 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. Hes 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.
 
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  #2  
Old 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.
 
  #3  
Old 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.

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Old 09-09-14, 07:36 PM
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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.
That sounds like a 2-conductor cable, black, white bare. It can only be used for 120 volts or 240 volts. It can not be used for a 120/240 sub panel. You need a 120/240 sub panel for a dryer because a dryer uses a 120/240 receptacle..
5-50R receptacle
That is a 120 volt receptacle not a 240 volt receptacle. The two conductor cable described is consistent with a 120 volt feed.
 
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Old 09-09-14, 07:59 PM
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Not all clothes dryers are 120/240 volts!
 
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Old 09-09-14, 09:15 PM
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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.
 
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Old 09-10-14, 02:19 AM
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Hopefully Fred is not a one-post wonder.
 
  #8  
Old 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.
 
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Old 09-10-14, 08:05 AM
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So are you going to have lights? You can't have a separate cable for lights because it is detached and you have no neutral for a 120 volt circuit needed for lights.
 
  #10  
Old 09-10-14, 08:08 AM
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There is a separate circuit for light already.
 
  #11  
Old 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.
 
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Old 09-10-14, 08:14 AM
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There is a separate circuit for light already.
A code violation and should have been abandoned when the 240 was run. You can not have two power sources to a detached structure. Both cables to the garage need to be abandoned and replaced with a 3-conductor cable (two hots, neutral, ground) and a subpanel. What is there was never code compliant.
 
  #13  
Old 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  
Old 09-10-14, 11:32 AM
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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:
and the green was attached to the neutral bus.
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.
 

Last edited by ray2047; 09-10-14 at 05:55 PM.
  #15  
Old 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  
Old 09-10-14, 06:23 PM
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No need for additional ground since this will only house 220V circuits. Correct?
If by additional ground you mean a ground rod, yes you need to install a ground rod. Just curious since straight 240 volt dryers are somewhat rare, what kind of dryer do you have?
 
  #17  
Old 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  
Old 09-10-14, 06:50 PM
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Why would i need ground rod as this is handled by the main panel.
A subpanel in a detached building requires a ground rod to be installed.

When i mentioned ground i was referring to a separate ground bus in the sub panel.
My opinion is you would need a separate ground bar because you have a ground and no neutral. Although using the neutral bus as a ground bar would work IF THE BONDING SCREW WERE INSTALLED, I don't think it is kosher by code. I'd like to hear other opinions. Using the neutral bus as a ground bar would also lead one to believe that 120 volt circuits could be added to the subpanel.

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!
http://www.samstores.com/product-whi...olt-21995.html
 

Last edited by CasualJoe; 09-10-14 at 07:06 PM.
  #19  
Old 09-10-14, 07:19 PM
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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.
Yes, but what are you going to do for lights and 120 receptacles?
 
  #20  
Old 09-10-14, 07:50 PM
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Interesting from Whirlpool WED5550YW High Efficiency Cabrio Dryer 220 volt | Multisyste
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.
I wonder if it will smoke or do something else odd?
 
  #21  
Old 09-10-14, 08:20 PM
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Motor will not run at the correct speed and may have a shortened life.
 
  #22  
Old 09-10-14, 08:25 PM
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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.
  #23  
Old 09-11-14, 01:47 PM
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OK thanks for all the help I will call someone else to make this right.
 
  #24  
Old 09-11-14, 02:32 PM
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The dryer won't work correctly if it is 50Hz regardless of what anyone does.
 
  #25  
Old 09-11-14, 06:05 PM
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Sometimes people don't want to hear that there is no right way to do the wrong thing.
 
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