Subpanel Question

Reply

  #1  
Old 10-19-05, 11:44 AM
MoneyMan
Visiting Guest
Posts: n/a
Question Subpanel Question

I am running a sub panel (110V, 60 amp) to my workshop that sits about 70 feet from my electrical service. My home has a fuse panel that is not grounded. I ran 10-3 cable to my shop underground through conduit, and installed two circuit breakers in a sub panel in my workshop. One breaker is a 110 v 30 amp for an RV outlet, and the other is a 20 amp to power my shop. I also bought a grounding rod to install a ground. 30 amps is the most I will be using at any one time, and then only occasionally.

Here's my question(s):
1. Can I install the ground rod at the shop, and run the ground from the neutral bar in the shop, or does the grounding rod need to be near the main panel?

2. I have four empty places for round fuses in my panel. Can I connect each hot lead to a separate round fuse connection, and the one neutral wire and ground wire to the neutral bar in the main panel to give power to the sub panel?

 
Sponsored Links
  #2  
Old 10-19-05, 11:54 AM
R
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
If your main panel is truly not grounded then you need to ground it. Is it possible that it is grounded and you just don't realize it? Is there a wire run to your incoming cold water pipe?

Is this sub panel in a detached building, or is it in the same building as your main panel? If this is a detached building then you need a ground rod. If in the same building no ground rod.

Since you ran 10 gage wire for the sub panel, you need to use 30 amp fuse max in your main panel. You need a proper 240 volt connection for the cable to the sub panel. You can't just grab two fuses at random.
 
  #3  
Old 10-19-05, 12:02 PM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 43 Votes on 41 Posts
I am running a sub panel (110V, 60 amp) to my workshop that sits about 70 feet from my electrical service. My home has a fuse panel that is not grounded. I ran 10-3 cable to my shop underground through conduit, and installed two circuit breakers in a sub panel in my workshop. One breaker is a 110 v 30 amp for an RV outlet, and the other is a 20 amp to power my shop. I also bought a grounding rod to install a ground. 30 amps is the most I will be using at any one time, and then only occasionally.
First, you should address the grounding problem in the main panel.

10-3 NM cable (Romex) is unacceptacle for use underground; it is not water proof. I hope that you actually used 10-3 UF-B cable which would be acceptable for use underground. Three conductor cable plus ground is for providing a 120/240V subpanel, not 120V.

Originally Posted by MoneyMan
1. Can I install the ground rod at the shop, and run the ground from the neutral bar in the shop, or does the grounding rod need to be near the main panel?
It is required that you install a ground rod for a subpanel in a detached structure.

I have four empty places for round fuses in my panel. Can I connect each hot lead to a separate round fuse connection, and the one neutral wire and ground wire to the neutral bar in the main panel to give power to the sub panel?
That will work to power the subpanel. You need to be certain that the two fuses are 30A and that they are on opposite legs of your incoming service. The fuses are on seperate legs of the service if they measure 240V between the hot poles.
 
  #4  
Old 10-19-05, 12:06 PM
MoneyMan
Visiting Guest
Posts: n/a
I used 10-3 outdoor wiring, and ran it in PVC (gray) conduit. I checked before purchasing, and was told by the electrical professional at the home improvement store that it was approved for underground use even without conduit.

The shop is detached, so I will put the ground rod there and connect it to the sub panel.

The fuses will be on separate legs of the service, and 30 amp each.

Thanks for your replies.
 
  #5  
Old 10-19-05, 12:15 PM
R
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
Originally Posted by MoneyMan
[I] was told by the electrical professional at the home improvement store...
This is usually an oxymoron. Many times the people working sat the home improvement stores give out incorrect information. Don't rely on advice from those stores.

As for you using 10-3 UF wiring in conduit. I would replace it with proper THWN wires.

Next question. How deep did you bury the conduit? You may need to rethink your whole plan if you didn't bury the conduit deep enough.
 
  #6  
Old 10-19-05, 12:18 PM
MoneyMan
Visiting Guest
Posts: n/a
About 6 inches average depth. Why would this matter?

The wiring is actually UF-B, and it is rubber casing.
 
  #7  
Old 10-19-05, 12:32 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
If the cable is UF-B, and it's already in conduit, I would not replace it if it was buried deep enough. However, 6" deep is far short of what is required by the electrical code. You need at least 18" if in conduit, or 24" if not in conduit. This is minimum depth, not average.

Furthermore, if you installed the UF-B piece by piece as you assembled the conduit, then it will probably fail eventually due to the interaction of the PVC glue and the insulation. If you pulled the UF-B through after the conduit was completed, then pull it out, rent a trencher, and rebury it 24" deep without conduit.

You need grounding rods at both buildings.
 
  #8  
Old 10-19-05, 12:35 PM
R
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
Is this metal conduit or PVC?

You're probably going to need GFCI protection on the wire before it leaves the house.

In my opinion, you should be deeper anyway.
 
  #9  
Old 10-19-05, 12:36 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
GFCI won't help.
 
  #10  
Old 10-19-05, 12:42 PM
MoneyMan
Visiting Guest
Posts: n/a
Originally Posted by John Nelson
... if you installed the UF-B piece by piece as you assembled the conduit, then it will probably fail eventually. If you pulled the UF-B through after the conduit was completed, then pull it out, rent a trencher, and rebury it 24" deep without conduit.
Piece by piece? The UF-B is one solid piece. The conduit is what was installed in pieces. I pulled the cable through each piece of the conduit and then glued the conduit together as I moved along, and then buried the conduit after I was finished. I made sure that the pipe was cleaned and glued properly, twisting the joints as I moved along, as one does when using PVC to run water.

Is there any reason that I should pull the conduit out and run it again, other than it not being deep enough?
 
  #11  
Old 10-19-05, 12:43 PM
MoneyMan
Visiting Guest
Posts: n/a
Originally Posted by racraft
Is this metal conduit or PVC?
PVC. I would never bury metal conduit for electricity.
 
  #12  
Old 10-19-05, 12:47 PM
R
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
As John stated, you need to go deeper. You also need to replace the cable, as the PVC glue has damaged the cable and it will fail.

As John said, start over. Direct bury the cable or use conduit, but start over with new cable, and bury it deep enough this time.
 
Reply
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


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: