Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 05-19-2008, 09:56 PM   #1
Newbie
 
Join Date: May 2008
Posts: 4
Rewards Points: 0
Share |
Default

Detached shed/shop rewire


I am about to do some repair work on an old 9x15 Handi-House that has water damage from a leaking roof. I am going to tear out the chipboard that covers the framing and replace it. While I'm at it, I was going to rewire it to suit me better. The original owner had some wire stapled to the chipboard going to outlets, and some in EMT conduit feeding the lights. I intend to put all the wiring behind the new walls and ceiling.

In preparation to do this, I started looking at how everything is wired. 10/2 UF cable feeds an even older shed from a 30A breaker in the house (distance of probably ~30 ft.). The shed I'm dealing with is fed from that wire with 12/2 NM spliced into the 10/2 underneath the oldest shed and wrapped in a mound of electrical tape (!!!). This 12/2 goes into a conduit and underground, then comes back up out of the ground under the newer shed (not sure if there's any conduit on this end). It then goes up into the shed through EMT into an old 30A disconnect switch. It appears that the ground and neutral wires are connected to the same lug in the middle of the switch. This disconnect switch has burn marks on the contacts, and it does arc a bit when the switch is being closed. 12/2 feeds all the outlets and lighting in the shed on one circuit. There does not appear to be any ground rod.

Obviously, the 12/2 splice into the 10/2 is a very bad thing. I am not sure how I'm going to deal with that since the splice is just hanging in the open under the old shed. I suppose I could attach a box under the old shed and make the connections there, sending one 10/2 into that shed (which also has a 30A disconnect) and one back underground to the newer shed. I will need to replace the 12/2 NM with 10/2 UF and place it in conduit where it enters and exits the ground. Is this okay? Do I need to strip the outer jacket off where it is in the conduit? (I have seen references to this for heat dissipation purposes, but it was related to burying cable in conduit for the full length of the run, not just curves at entry/exit.)

Otherwise, here is what my best understanding is on how I should deal with the rest of the project. I intend to get something between a 60A and 125A main lug panel to use as a subpanel inside the newer shed. If this has the capacity for more than six circuits, I will have to use a disconnect switch before the subpanel or get one with a main breaker, right (six disconnect rule)? I also need a ground rod, which would be connected to the ground bar in the disconnect (if I need one) or the subpanel. The ground wire from the 10/2 would also need to be connected to the ground bar. I would NOT connect neutral and ground in the subpanel or disconnect. Then I would have two or three circuits in the shed using 12/2 NM. Probably one for lighting on a 15A breaker and two others for power tools. If I am going to have equipment on these that are rated at 15A, I need to install 20A receptacles, right? Something about using only 80% of the rated ampacity?

I don't plan to use the old 30A disconnect switch because its label states it should only be used with 60 degree rated wire. My understanding is that today's wire is usually rated for 90 degrees. Is this correct? Also, I don't like the burn marks and the arcing that occurs, even though it's ever so slight.

Is there anything special I need to do related to having two separate sheds fed like they are? Do I need a ground rod for each, or is one enough? There is no other metallic path between the house and either of the sheds.

Thanks for your help!

gtmatt is offline   Reply With Quote
Old 05-22-2008, 11:33 PM   #2
Newbie
 
Join Date: May 2008
Posts: 4
Rewards Points: 0
Default

Detached shed/shop rewire


Bump...anybody have any input on this? I am going to start tearing things out tomorrow, so any help would be appreciated!

gtmatt is offline   Reply With Quote
Old 05-23-2008, 01:35 AM   #3
Newbie
 
Join Date: May 2008
Posts: 5
Rewards Points: 0
Default

Detached shed/shop rewire


Replace the 10/2 with 10 ga. grounded Romex and get rid of the old stuff.
Holden McGroin is offline   Reply With Quote
Old 05-23-2008, 10:53 AM   #4
Licensed Electrician
 
jrclen's Avatar
 
Join Date: Feb 2008
Location: central wisconsin
Posts: 982
Rewards Points: 0
Default

Detached shed/shop rewire


Quote:
Originally Posted by gtmatt View Post
I am about to do some repair work on an old 9x15 Handi-House
Ok, let's see if I can give you some help. You have issues and many options as you know. It would take way to long to list them all. So I will try to keep it simple and go from there.

Quote:
10/2 UF cable feeds an even older shed from a 30A breaker in the house (distance of probably ~30 ft.). The shed I'm dealing with is fed from that wire with 12/2 NM spliced into the 10/2 underneath the oldest shed and wrapped in a mound of electrical tape (!!!).

This 12/2 goes into a conduit and underground, then comes back up out of the ground under the newer shed
The 12/2 NM cannot be used underground even in conduit. It must be replaced with UF.

Quote:
It then goes up into the shed through EMT into an old 30A disconnect switch. It appears that the ground and neutral wires are connected to the same lug in the middle of the switch.
The ground and neutral need to be kept separated everywhere except the main service panel. If you just ran the neutral through this disconnect without attaching it to the lug, you would be ok.

Quote:
There does not appear to be any ground rod.
If you keep this a single circuit, as it is now, you would not need a ground rod.

Quote:
Obviously, the 12/2 splice into the 10/2 is a very bad thing. I am not sure how I'm going to deal with that since the splice is just hanging in the open under the old shed. I suppose I could attach a box under the old shed and make the connections there, sending one 10/2 into that shed (which also has a 30A disconnect) and one back underground to the newer shed. I will need to replace the 12/2 NM with 10/2 UF and place it in conduit where it enters and exits the ground. Is this okay?
Yes, any 12 in the circuit would require you to replace the 30 amp breaker with a 20 amp breaker. If you make the splice in a box and the box remains accessible, you would be ok. Yes, you need to replace the NM with UF. I will talk about size in a minute.

Quote:
Do I need to strip the outer jacket off where it is in the conduit?
No. You can install the UF in conduit as is, or you can bury it direct without conduit.

Quote:
I intend to get something between a 60A and 125A main lug panel to use as a subpanel inside the newer shed.
Why would you do this? You only have a single circuit. It is either 30 amp or will be 20 amp depending on what you do next. Let's assume you desire the 30 amp capacity. Everything in the 1st shed must be wired with #10 wire (or follow what I recommend for the second shed) and a #10 run to the 2nd shed.

At the 2nd shed you could install a 2 circuit disconnect with either fuses or circuit breakers. In this case, all the #10 would be protected by the circuit breaker in the house. You could then wire the shed with 12 or 14 and protect those circuits with 20 or 15 amp fuses or circuit breakers. In this case a ground rod would be required at the 2nd shed and would be connected to the ground wire only. The neutral would simply be spliced to the neutrals of the new circuits or could be terminated on an isolated neutral bus in the disconnect. The grounds would have their own bus which would also be bonded to the case of the disconnect. No main disconnect would be required.

Quote:
Then I would have two or three circuits in the shed using 12/2 NM. Probably one for lighting on a 15A breaker and two others for power tools. If I am going to have equipment on these that are rated at 15A, I need to install 20A receptacles, right? Something about using only 80% of the rated ampacity?
Two circuits would be plenty. A 15 and 20 or (my choice) two 20 amp circuits. If you have more than one receptacle outlet on either or both of these circuits, you can use 15 or 20 amp receptacles. If you install only one receptacle outlet on a 20 amp circuit, it must be a 20 amp receptacle. You can ignore the 80% rule, it does not apply in this situation.

Quote:
I don't plan to use the old 30A disconnect switch because its label states it should only be used with 60 degree rated wire. My understanding is that today's wire is usually rated for 90 degrees. Is this correct? Also, I don't like the burn marks and the arcing that occurs, even though it's ever so slight.
The wire rating is for ampacity and you are protecting the wire at the 60 degree rating anyway. So you can ignore this also.

Quote:
There is no other metallic path between the house and either of the sheds.
Great. That simplifies things. What you do in the first shed will detirmine whether you need a ground rod there. You can certainly add one if you wish.

I hope this gets you started. I'm sure you now have more questions. But you can proceed now with some of the work. Wire the walls and ceiling of the 2nd shed normally, using two circuits, and we can hash out the rest as you go.
__________________
John

Last edited by jrclen; 05-23-2008 at 10:58 AM.
jrclen is offline   Reply With Quote
Old 05-23-2008, 07:43 PM   #5
Newbie
 
Join Date: May 2008
Posts: 4
Rewards Points: 0
Default

Detached shed/shop rewire


Quote:
Originally Posted by jrclen View Post
The 12/2 NM cannot be used underground even in conduit. It must be replaced with UF.
Turns out it is actually UF -- when I took it out of the conduit it was going through into the newer shed, I could read the labeling (I couldn't before because I was looking at sheathing that was exposed under the shed, so I didn't see "UF" on it). I am going to replace it with 10/2 UF because I want a 30A circuit.

Quote:
Originally Posted by jrclen View Post
If you keep this a single circuit, as it is now, you would not need a ground rod.
Okay. I didn't know that -- I guess it's a special allowance for if you just run one circuit to a detached building? I am going to have multiple circuits in the shed, so I will have to drive a rod.

Quote:
Originally Posted by jrclen View Post
No. You can install the UF in conduit as is, or you can bury it direct without conduit.
Without conduit even for the curved part as the cable enters the ground and turns horizontal? I would think I'd at least have to put it in conduit from the bottom of the shed to where it enters this ground. Is this not required?

Quote:
Originally Posted by jrclen
Quote:
Originally Posted by gtmatt
I intend to get something between a 60A and 125A main lug panel to use as a subpanel inside the newer shed.
Why would you do this? You only have a single circuit. It is either 30 amp or will be 20 amp depending on what you do next. Let's assume you desire the 30 amp capacity. Everything in the 1st shed must be wired with #10 wire (or follow what I recommend for the second shed) and a #10 run to the 2nd shed.
I would do it so I can get multiple circuits so I can run, say, a 15 amp tool while also running a shop vac and the lights. I am using 12/2 inside the shed, so I wouldn't be able to do that without at least two circuits. Why everything in the first shed #10? If the 10/2 goes into a fusible disconnect switch, doesn't that allow me to use 12/2 for the circuit in the first shed?

Quote:
Originally Posted by jrclen View Post
At the 2nd shed you could install a 2 circuit disconnect with either fuses or circuit breakers. In this case, all the #10 would be protected by the circuit breaker in the house. You could then wire the shed with 12 or 14 and protect those circuits with 20 or 15 amp fuses or circuit breakers. In this case a ground rod would be required at the 2nd shed and would be connected to the ground wire only. The neutral would simply be spliced to the neutrals of the new circuits or could be terminated on an isolated neutral bus in the disconnect. The grounds would have their own bus which would also be bonded to the case of the disconnect. No main disconnect would be required.
Very good -- thanks for the confirmation on all that.

Quote:
Originally Posted by jrclen View Post
Two circuits would be plenty. A 15 and 20 or (my choice) two 20 amp circuits. If you have more than one receptacle outlet on either or both of these circuits, you can use 15 or 20 amp receptacles. If you install only one receptacle outlet on a 20 amp circuit, it must be a 20 amp receptacle. You can ignore the 80% rule, it does not apply in this situation.
So I can run a 15A tool out of a 15A receptacle? What if I have that 15A tool plus something else going on the same circuit (12/2 so it would be breakered at 20A) -- wouldn't that overload the rating on 15A receptacles on the circuit?

Quote:
Originally Posted by jrclen View Post
I hope this gets you started. I'm sure you now have more questions. But you can proceed now with some of the work. Wire the walls and ceiling of the 2nd shed normally, using two circuits, and we can hash out the rest as you go.
Yeah, thanks for the answers. I did not get through taking everything apart yet, so I won't get to wiring until tomorrow afternoon.
gtmatt is offline   Reply With Quote
Old 05-24-2008, 12:00 AM   #6
Newbie
 
Join Date: May 2008
Posts: 4
Rewards Points: 0
Default

Detached shed/shop rewire


Okay, more questions as I've been researching some more:

From what I've read, it appears that my shed circuits need GFCI protection. So can I accomplish this with a single 30A GFCI circuit breaker in the main panel in the house? They are more expensive, but from what I've read the outlet-based ones fail often.

Can EMT be used for protecting the UF from shed exit to underground after the 90 degree turn? Or do I need something like RMC?

What is the requirement for the ground rod to subpanel ground bus wire? Specifically the size. I have read that the minimum is AWG 8. Does this wire need to be protected in conduit while outside the shed until the ground rod and/or where it is inside the shed?

Thanks!
gtmatt is offline   Reply With Quote
Old 05-24-2008, 09:25 AM   #7
Licensed Electrician
 
jrclen's Avatar
 
Join Date: Feb 2008
Location: central wisconsin
Posts: 982
Rewards Points: 0
Default

Detached shed/shop rewire


Quote:
Originally Posted by gtmatt View Post
Without conduit even for the curved part as the cable enters the ground and turns horizontal? I would think I'd at least have to put it in conduit from the bottom of the shed to where it enters this ground. Is this not required?
Only if it is subject to physical damage. If it is, sleeve the wire in sch 80 PVC.

Quote:
I would do it so I can get multiple circuits so I can run, say, a 15 amp tool while also running a shop vac and the lights. I am using 12/2 inside the shed, so I wouldn't be able to do that without at least two circuits. Why everything in the first shed #10? If the 10/2 goes into a fusible disconnect switch, doesn't that allow me to use 12/2 for the circuit in the first shed?
You can certainly do this with the fuse protecting the 12/2.

Quote:
So I can run a 15A tool out of a 15A receptacle? What if I have that 15A tool plus something else going on the same circuit (12/2 so it would be breakered at 20A) -- wouldn't that overload the rating on 15A receptacles on the circuit?
A 20 amp (or more) device will not plug into a 15 amp receptacle. It has a special plug. Plugging two 15 amp devices into a 15 amp duplex receptacle is still plugging only a 15 amp load into each 15 amp rated receptacle. Remember, each individual receptacle is rated at 15 amps and a duplex has two of those.
__________________
John

Last edited by jrclen; 05-24-2008 at 09:27 AM.
jrclen is offline   Reply With Quote
Old 05-24-2008, 09:40 AM   #8
Licensed Electrician
 
jrclen's Avatar
 
Join Date: Feb 2008
Location: central wisconsin
Posts: 982
Rewards Points: 0
Default

Detached shed/shop rewire


Quote:
Originally Posted by gtmatt View Post
From what I've read, it appears that my shed circuits need GFCI protection. So can I accomplish this with a single 30A GFCI circuit breaker in the main panel in the house? They are more expensive, but from what I've read the outlet-based ones fail often.
Only the receptacle outlets need GFCI protection. I would use a GFCI receptacle in the shed at the first receptacle in the circuit and then connect other receptacles to the load side of that one to protect the others. The GFCI receptacles are very reliable and would save you a hike to the house should one trip. They are usually cheaper too. But this is your call.

Quote:
Can EMT be used for protecting the UF from shed exit to underground after the 90 degree turn? Or do I need something like RMC?
It would be far less trouble for you to use sch 80 PVC conduit. Metal conduit brings up bonding issues.

Quote:
What is the requirement for the ground rod to subpanel ground bus wire? Specifically the size. I have read that the minimum is AWG 8. Does this wire need to be protected in conduit while outside the shed until the ground rod and/or where it is inside the shed?
You read correctly. #8 copper minimum. Sleeve it in sch 80 PVC to protect it where it is likely to be damaged.

__________________
John
jrclen is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Painting the inside side of Tar Paper; unfinished detached garage cityparkmark Building & Construction 8 03-03-2008 09:15 AM
Detached Garage Sub Panel Grounding Q integlikewhoa Electrical 13 01-01-2008 06:22 AM
Aluminum rewire plan ra_doliv Electrical 13 07-06-2007 05:37 PM
Best way to insulating a heated detached cement block garage Joe Nulph Building & Construction 1 03-06-2006 10:30 AM
Detached Garage Insulation Unregistered Building & Construction 2 02-28-2004 03:31 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.