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 11-05-2007, 02:10 PM   #1
Member
 
Join Date: May 2007
Posts: 220
Share |
Default

Bizarre Workshop Wiring


I bought this older home that has a pretty big (12x24) workshop that the previous owner had built. I've been using it myself for a few years and it's fed by an overhead supply line.

I'm needing to reroute that to be a direct burial cable so I started looking into how they had fed it... here's the wierd part...

They took a 220 volt circuit, (2 wire plus one ground) from the main panel to the shed. In the shed, they put in 2 new grounding rods and tied the 2 ground wires together through a large fuse on/off switch/panel.

The outlets and fixtures in the shed have seperate neutrals, etc. that are then tied to the ground via the switch/panel in the shed. So now the shed has 110V circuits. ie; they use the hot from each leg of the main panels 220V circuit and run that to ground via the neutral.

Obviously, everything "works", but is this optimal or to code in Canada? Or when I re-route the overhead, should I run new 3 wire ciruit to the shed?

I hope I explained it well enough....


Last edited by slakker; 11-05-2007 at 02:13 PM.
slakker is offline   Reply With Quote
Old 11-05-2007, 05:02 PM   #2
Union Electrician
 
goose134's Avatar
 
Join Date: Nov 2007
Location: Chicago, USA
Posts: 615
Default

Bizarre Workshop Wiring


I can't be sure but this is a good way to find out if what I'm thinking is actually happening. Turn on the lights, and plug something into a couple of outlets and let them run. Then take an amprobe and take a reading on your ground. Just curious.

goose134 is offline   Reply With Quote
Old 11-05-2007, 09:09 PM   #3
Member
 
Join Date: May 2007
Posts: 220
Default

Bizarre Workshop Wiring


No amperage on the ground as far as I can tell... I used one of those induction type amp meters... Ground is connected to "ground" via 3 seperate points at the switch/panel... To the Main Panel in the house via the 2 wire and 1 ground wire and also to the 2 grounding rods...

There's obviously current going back on any of the individual neutral returns...
slakker is offline   Reply With Quote
Old 11-05-2007, 09:14 PM   #4
Union Electrician
 
goose134's Avatar
 
Join Date: Nov 2007
Location: Chicago, USA
Posts: 615
Default

Bizarre Workshop Wiring


Well, it sounds like you are fine. The way you described the incoming feed, I was concerned that they used the ground as a neutral. But re-reading your post it sounds like the neutral is derived seperately at the shed. It seems like it should be ok. Anyone else?
goose134 is offline   Reply With Quote
Old 11-06-2007, 10:51 AM   #5
Member
 
Join Date: Jul 2007
Posts: 1,590
Default

Bizarre Workshop Wiring


It doesn't sound fine to me. First, you should have two hot wires, 1 neutral and one ground coming from the main panel and going to the subpanel in the shed. The neutrals should be on a seperate bar than the grounds in the subpanel and the neutral and ground bar should not be bonded to each other. The ground rod at the shed should go to the ground bar in the subpanel. But I really don't understand what you are saying with your wiring description. You seem to be confusing neutral with ground.

Fir
jogr is offline   Reply With Quote
Old 11-06-2007, 12:32 PM   #6
Member
 
Join Date: May 2007
Posts: 220
Default

Bizarre Workshop Wiring


I was hoping to be more articulate... imagine what you've described but no neutral back to the main panel PLUS the neutral and ground are bonded together at the sub panel/switch.

You mentioned neutral and ground should NOT be bonded together... why? It's already bonded in the main panel... is there a ground loop issue I should consider?

However, my real question is more around what are the safety concerns and issues. The long term solution is to re-run the whole circuit, just want to get a sense of what type of priority this is given all the other stuff I have to fix up in this "frankenstien" of a house...
slakker is offline   Reply With Quote
Old 11-06-2007, 01:12 PM   #7
Member
 
Join Date: Apr 2007
Location: Downeast Maine
Posts: 999
Default

Bizarre Workshop Wiring


Sounds like a normal 3-wire service to a detached building sub-panel. If there are NO other metallic connections to the main building (copper water pipe, cable, telephone wire, etc) then my understanding is that it's an allowable way to wire a subpanel. I hear that in 2009 it will no longer be allowed for new installations.

If you wanted to "update" it, or if you have a copper water pipe going out there or something, then you just need to pull a ground wire out to the garage, hook all white wires to the neutral bar, all greens/bare to a ground bar, and then remove the screw that bonds the neutral buss to the box case. That way ground and neutral will be separate all the way back to the house. You still need the ground rods, but they should be attached to the ground bar in the sub.

I'm not a pro, so take my advice with a grain of salt, but it sounds to me like a safe 3-wire installation, from what you've said.

Edit: I just noticed that you plan to convert this to an underground feed. In that case I'd definitely just run 4 wires, and separate ground and neutral in the sub, as I described above. It's safe the way it is now, but for the cost of one more wire, I'd definitely update it so you don't have to worry about future expansions.
NateHanson is offline   Reply With Quote
Old 11-06-2007, 01:19 PM   #8
Member
 
Join Date: Jul 2007
Posts: 1,590
Default

Bizarre Workshop Wiring


I guess you were articulate - I just couldn't believe what I was reading. So they used the ground wire to serve as the neutral and bonded neutral to ground in subpanel. Not good.

Having your ground and neutral bonded in the subpanel makes it so you can get fried under certain circumstances. I think one of the real electricians who comes on this site posted a nice diagram in another thread.

Your system right now will make things run so everything gives the illusion of being ok. But under certain conditions death can result.

It appears that things could be corrected by running a 4 wire to the subpanel and separating the neutrals and grounds. But with the fundamentals being wrong you better check out everything very carefully.
jogr is offline   Reply With Quote
Old 11-06-2007, 01:24 PM   #9
Member
 
Join Date: Jul 2007
Posts: 1,590
Default

Bizarre Workshop Wiring


Nate types faster than me and brings up an interesting point. Perhaps if there is no other connection between the building the risk is mitigated???
jogr is offline   Reply With Quote
Old 11-06-2007, 01:40 PM   #10
Member
 
Join Date: Apr 2007
Location: Downeast Maine
Posts: 999
Default

Bizarre Workshop Wiring


Quote:
Originally Posted by jogr View Post
Nate types faster than me and brings up an interesting point. Perhaps if there is no other connection between the building the risk is mitigated???
I'm pretty sure that his setup not only "mitigates the risk", but is actually completely code compliant (at least in ME, USA). I just installed a 3-wire feeder for a subpanel in a detached shop. I pulled a permit and it passed inspection. Sounds just like the one the poster describes.
NateHanson is offline   Reply With Quote
Old 11-06-2007, 02:02 PM   #11
Electrician philosopher
 
Join Date: Aug 2007
Location: Lilburn, GA
Posts: 838
Default

Bizarre Workshop Wiring


It's compliant, but not for long. I would add the fourth wire if I was repulling this, keeping all the neutrals and grounds seperate. Google objectionable current.

Edit to add....I've never been to Canada!!! Don't know the rules up there!!!
Andy in ATL is offline   Reply With Quote
Old 11-06-2007, 07:27 PM   #12
Member
 
Join Date: May 2007
Posts: 220
Default

Bizarre Workshop Wiring


Thanks for all the feedback, I'll double check the codes for up here and see what it says... I don't have a full code book, but one of those abridged versions for homeowners, so we'll see what I can find...

BTW> There are no other metallic runs to the shed... just the overhead feeder...
slakker is offline   Reply With Quote
Old 11-06-2007, 07:33 PM   #13
Electrician philosopher
 
Join Date: Aug 2007
Location: Lilburn, GA
Posts: 838
Default

Bizarre Workshop Wiring


I guess the moral of the story is.... no matter if you are in
Can, the US , or frikkin Honduras... It is MUCH BETTER AND SAFER to keep the grounds and neutrals seperate except where they are bonded together at the service entrance to your house.
Andy in ATL is offline   Reply With Quote
Old 11-06-2007, 11:10 PM   #14
Union Electrician
 
goose134's Avatar
 
Join Date: Nov 2007
Location: Chicago, USA
Posts: 615
Default

Bizarre Workshop Wiring


Andy, I agree with you 100%. The neutral should only be bonded at the point of service. I said it was OK because of the installation being overhead. If there is a raceway installed you should never bond the neutral again. This was one of the reasons I had asked him to meter his ground. My concern was the ground was functioning as a return to the main load center. I would recommend piping it over to the shed and remove the bonds.
goose134 is offline   Reply With Quote
Old 11-07-2007, 10:09 AM   #15
Member
 
Join Date: May 2007
Posts: 220
Default

Bizarre Workshop Wiring


Quote:
Originally Posted by goose134 View Post
I would recommend piping it over to the shed and remove the bonds.
I'm not sure I understand... can you elaborate? Don't want to screw it up when I redo this...

slakker 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
need: "new construction" book on wiring bjherron Electrical 4 09-21-2007 02:23 PM
Replacing wiring in middle of run, ungrounded lighting circuit alexz Electrical 3 07-05-2007 08:53 PM
Wiring an outlet in the garden wackerjr Electrical 8 05-28-2006 08:18 AM
Knob & Tube wiring - How concerned should we be? hotdiggitydog Electrical 6 04-11-2006 07:52 PM
Garage - Protecting wiring installation eastment Electrical 4 11-26-2005 11:52 AM




Top of Page | View New Posts

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