Electrical Service to Shed

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  #1  
Old 07-29-05, 10:28 AM
Jaywyatt
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Electrical Service to Shed

Hello all and thanks for reading this
I am going to run a 240v 60a service off of my house to my shed.The info that I got was that I needed 3 6awg (White,Black,Red)wires and 1 10awg (Green) ground wire. Is this correct? Also that I should run it in 1inch PVC conduit buried 18'' deep.
Another question I have is do I need a seperate ground rod for the shed or is the one for the house sufficient? Thanks for your advice.
Jay
 
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  #2  
Old 07-29-05, 10:49 AM
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What is the distance to the shed from the main panel?

Yes, you need a ground rod at the shed.
 
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Old 07-29-05, 10:50 AM
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Personally I would use 1 1/4, it doest cost much more and is more common, way easier to pull wire. Yes, 6 wire is fine and you need a ground rod. How far is it to the shed and what kind of loads to you anticipate? Whoops, I see I got beat to it. If there is any distance my choice is number 2 alum for shed feeds and I still run it on a 60A breaker. You can buy the quad, 3 conductors and a ground wire. Its cheap and its ampacity rating is higher than number 6, good when V drop is a concern. It can be buried direct if needed.
 
  #4  
Old 07-29-05, 10:57 AM
Jaywyatt
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Originally Posted by racraft
What is the distance to the shed from the main panel?
60 Feet
Yes, you need a ground rod at the shed.
I thought it might.
 
  #5  
Old 07-29-05, 10:58 AM
Jaywyatt
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Is 10awg sufficient for the ground wire?
 
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Old 07-29-05, 12:01 PM
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Originally Posted by Jaywyatt
Is 10awg sufficient for the ground wire?
Yes, it is.
 
  #7  
Old 07-29-05, 12:32 PM
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If you go any higher than 60 in amp rating you will need a bigger ground wire.

If your supplies are coming from the big box stores your probably going to find that a 60 amp panel isnt available. Your best buy is going to be a 100 amp panel that will have 6 spaces and 12 circuits at 120 volts available if you use the tandem style breakers. You just feed it 60 amps as you plan. If you go to an electrical supply then they may have a maker that provides a 60 amp panel. Square d makes one that is a main lug only panel rated for 70 amps that provides 2 spaces and four circuits at 120 volt using tandems.
You also need to keep the neutral bar and ground bar seperate in the sub-panel in the shed. This may require purchasing a ground bar kit for the sub-panel.
The ground rod needs to be 5/8" and 8' long. You will need to run #6 solid copper grounding electrode conductor to the ground rod and fasten with ground rod clamp. It should be as close to the panel location as feasible. At the panel it will fasten to the ground bar.
When you come up into the shed you will need to mount the panel close to where you enter the shed with the conductors. Then it can serve as the required disconnect. If not then you need to install a disconnect. Then from that disconnect run your conductors and conduit to the panel location.
You are not required to have a main breaker in the sub-panel unless you have more than 6 breakers in the panel. Some people will suggest it is a good idea, so its your choice. It does increase the cost of the installation. IMO a main lug panel only is fine.

It is always a good idea to do a demand load calculation on the house panel to make sure it can support the sub-panel. See this link.....

http://www.selfhelpandmore.com/homew...calc/index.htm
 

Last edited by Roger; 07-29-05 at 01:37 PM.
  #8  
Old 07-29-05, 03:14 PM
Jaywyatt
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[QUOTE=Roger]If you go any higher than 60 in amp rating you will need a bigger ground wire.

Could I just go with a 6awg ground wire also or would it be difficult to connect at the panel? (I already have a green 6awg wire if thats the case)


The ground rod needs to be 5/8" and 8' long. You will need to run #6 solid copper grounding electrode conductor to the ground rod and fasten with ground rod clamp. It should be as close to the panel location as feasible. At the panel it will fasten to the ground bar.

Does this wire need to be run in conduit?
 
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Old 07-29-05, 03:44 PM
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Could I just go with a 6awg ground wire also or would it be difficult to connect at the panel? (I already have a green 6awg wire if thats the case)
I dont see any reason to do that...the #10 is fine. If in the event you need to go to 100 amp service your going to have to change out all the wires anyway. You could just install it then and even then it would only need to be 8 awg.

If it is exposed to physical damage where it is outside the shed it should be in conduit also it needs to be buried at least 6 inches under the ground to the ground rod but doesnt need to be in conduit.
 
  #10  
Old 07-30-05, 03:19 PM
Jaywyatt
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OK
I mounted a 100amp panel in the shed. I ran three 6awg wires (white, black, red) and one 10 awg green wire in 1" gray pvc conduit buried 18" deep. I installed a 5/8" 8' ground rod in the trench right at the shed and ran a 6awg solid copper bare wire from the rod into the shed. The neutral buss is not bonded on the panel I purchased but I noticed that it is bonded on the panel at the house. Is this correct? I also purchased a 60amp breaker to install in the house panel. The new shed panel has a 100 amp main breaker but this would be considered a disconnect switch right? The house panel is in a small attached shed with exposed wall studs. Do the wires need to be in conduit from where they enter the attached shed to the panel and if so what kind of conduit?
Thanks for all the advice
Jay
 
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Old 07-30-05, 07:45 PM
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I installed a 5/8" 8' ground rod in the trench
Vertically, I hope.

The neutral buss is not bonded on the panel I purchased but I noticed that it is bonded on the panel at the house. Is this correct?
Correct, and essential.

The new shed panel has a 100 amp main breaker but this would be considered a disconnect switch right?
Correct. It does not provide overcurrent protection--that is done by the 60-amp breaker back at the house.

Do the wires need to be in conduit from where they enter the attached shed to the panel and if so what kind of conduit?
Individual wires need to be in conduit everywhere. PVC is okay, but almost any kind would do.
 
  #12  
Old 07-31-05, 06:26 AM
Jaywyatt
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Yes the ground rod is installed vertically although it would have been easier to just lay it in the trench
Thanks for everyones help
I feel better that I know it was done right
Jay
 
  #13  
Old 07-31-05, 06:20 PM
tjbergy
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Add-on questions for clarification

I'm about to start a very similar project and was very excited to see this thread. Your advice is very helpful and has already answered a number of my questions. My project differs only in the distance between the two buildings (six feet) and that I'm only going to run a 40 amp service.

Questions:

Will I still need a separate grounding rod for the new breaker box?
If not, what is the recommended wire gage to run from the house breaker box ground bus to the new garage breaker box ground bus?

If a ground rod is needed for the new garage, can I connect both breaker boxes to the same grounding rod? Remember the distance is 6 feet.

Why is a separate neutral and ground bus required in the garage breaker box?
Voltage drop in the neutral?

Will 3 #8 wires handle the 40 amp service?

How close does the breakbox need to be to the garage enterance to serve as a disconnect?
 
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Old 07-31-05, 06:35 PM
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Will I still need a separate grounding rod for the new breaker box?
Yes.

If not, what is the recommended wire gage to run from the house breaker box ground bus to the new garage breaker box ground bus?
It's not an either/or. You need both. The grounding wire between buildings (the Equipment Grounding Conductor) serves a different purpose than the ground rod and the wire that connects it to the subpanel (the Grounding Electroded Conductor). The minimum size of the EGC depends on the size of the other conductors. Assuming these are #8 copper, the EGC must be at least #10.

If a ground rod is needed for the new garage, can I connect both breaker boxes to the same grounding rod? Remember the distance is 6 feet.
Not sure. Ask your inspector, or maybe someone else here will know.

Why is a separate neutral and ground bus required in the garage breaker box?
No, it has nothing to do with that. It's a safety issue. If you don't keep them separate, neutral current will flow on both the neutral wire and the EGC, and you don't want any non-fault current on the EGC.

Will 3 #8 wires handle the 40 amp service?
Yes, plus the EGC we discussed above.

How close does the breakbox need to be to the garage enterance to serve as a disconnect?
I didn't think there was a mandated distance, since the wire is already protected by the 40-amp breaker in the main. But I remember an earlier discussion that suggested that there were some rules here.
 
  #15  
Old 07-31-05, 10:30 PM
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Will I still need a separate grounding rod for the new breaker box?
Yes, it doesnt matter if it is 2 ft or hundred feet between panels if they are in seperate buildings


If a ground rod is needed for the new garage, can I connect both breaker boxes to the same grounding rod? Remember the distance is 6 feet.
No.... ground loops cannot be created between panels, your inspector will flag you for this.

How close does the breakbox need to be to the garage enterance to serve as a disconnect
Actually the "human entrance" has nothing to do with it. It's where the conductors or the panel feeder enter the building. A disconnect is required at the nearest point of entrance of the feeder to building. If the panel does not have a main breaker and happens to be immediately after the conductors enter the building then it can serve as the disconnect, provided it doesnt have more than six breakers in the panel. If more than six breakers then it must have a main breaker installed in the panel. This has been an area of considerable disagreement by many.
If your panel is going to be located on another wall or a fair distance from where the conductors enter the building then you will need to install a seperate disconnect where the feeders enter the building and then finish your wiring run to the sub-panel from that disconnect box. If a seperate disconnect is installed at the point of entrance of the feeder then the panel can be located anywhere you like.The code intent here is to have a readily recognizeable location from the exterior of the building as to the location of the disconnect. This disconnect if not the sub-panel is required by many local codes to be located on the exterior of the building.This is for safety purposes such as fire etc... One of the first things firemen do when responding to fire is to have power disconnected to the building.
 

Last edited by Roger; 07-31-05 at 11:49 PM.
  #16  
Old 08-01-05, 07:11 PM
tjbergy
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Job well done!

Thanks to both John and Roger. The information you both provided has been a great help.

Ted
 
  #17  
Old 08-06-05, 08:51 AM
Jaywyatt
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I have another question. I purchased a double breaker for the main house panel that says 60 amps on each breaker.Does this mean that any one of the 2 hot wires will pull 60a before the breaker trips and that I actually have 120a service to the shed? Or should I have gotten a breaker with 30a on each leg?
 
  #18  
Old 08-06-05, 09:28 AM
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What you have is a 60A _double pole_ breaker. This means that you can get 60A at 240V. This is the same amount of power as 120A at 120V, but it is called a _60A_ breaker, and it supplies a 60A feeder.

If you used #8 conductors as you suggested above, then this breaker is too large. If you used #6 conductors, then this breaker is probably just fine.

-Jon
 
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