ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
FPE in Germany
by NORCAL - 10/16/19 08:24 AM
Help with aging employee advice.
by Bill Addiss - 10/15/19 10:58 PM
Fuse blower plug?
by gfretwell - 10/13/19 03:23 PM
Power factor and transformer efficiency
by TeslaEdison - 10/13/19 04:05 AM
Permit Snafus...AHJs and Contractors Jump in
by HotLine1 - 10/10/19 07:35 AM
New in the Gallery:
FPE Breaker panel in germany
What is this for?
Who's Online Now
0 registered members (), 14 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
sub panel without equipment ground? #94107 07/06/05 06:04 PM
Joined: Sep 2004
Posts: 138
royta Offline OP
A customer has a sub-panel on an the inside of an exterior wall of a barn type building. I need to remove this panel and install a new panel on the other side of the wall (outside of the building). I guess that doesn't really matter to you.

Here's my situation. There is a meter/main combo on the side of the house which feeds a sub-panel located in the house. The main panel also fed a 240V branch circuit going to a disconnect located at the back of the house. Somebody before me removed the interior of the disconnect and used it as a junction box to feed the same sub-panel I am trying to relocate. Here's the problem, there is no equipment ground between the main and sub-panel. There are only two 120V legs and a Neutral between the two panels. For ground at the sub-panel, there is a grounding electrode. I am trying to squeeze under 2002 NEC 250.32(B)(2) and bond the neutral bar to the sub-panel can. It would be easy to pull an equipment ground between the junction box and the sub-panel, however it won't be so easy to get a ground between the junction box and the main panel (both are on exterior walls of the house). I qualify under parts 1 & 2 of the Article, but part 3 seems to catch me. Where...ground-fault protection of equipment has not been installed on the common ac service. Since this is a residential installation, there is obviously ground-fault protection located somewhere in the house. However, it is not coming from the main panel, only the sub-panel located in the house. Does this still fall under the "common ac service"? Besides this, the junction box (old disconnect), contains splices of the current carrying conductors feeding the barn sub-panel.

What can I legally get away with?

2017 / 2014 NEC & Related Books and Study Guides
Re: sub panel without equipment ground? #94108 07/06/05 10:12 PM
Joined: Sep 2003
Posts: 649
winnie Offline
I am not sure about the exact wording here, which _might_ cause problems if there are GFCIs on branch circuits. However, as far as the _reason_ for part 3 of this article, GFCIs on branch circuits are not relevant.

The issue is ground fault detection on the entire service. A bond between neutral and ground at the subpanel would be a connection between circuit conductors and ground downstream of this ground fault detection. Depending upon how the ground fault detection is implemented, such a bond could desensitize the ground fault detection or could cause false tripping.

I rather doubt that this residence has service ground fault protection [Linked Image]


Re: sub panel without equipment ground? #94109 07/06/05 10:15 PM
Joined: Sep 2004
Posts: 138
royta Offline OP
Excellent. It looks like I go back tomorrow and finish the job. Thanks.


edit -- How do I bond the junction box? Do I attach the Neutral to it?

[This message has been edited by royta (edited 07-06-2005).]

Re: sub panel without equipment ground? #94110 07/06/05 11:46 PM
Joined: Sep 2003
Posts: 649
winnie Offline
It sounds to me like the 'junction box' is on the side of the building with the service. Since 250.32(B)(2) applies to _detached_ structures, it seems to me like you would have to run an equipment ground to the junction box...which on re-reading your original post seems to be the problem.

Remember that the only time you can run a subpanel like a 'service' with bonded ground and neutral is if the subpanel is in a detached structure with no metallic pathways between the two structures.



2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
Attic Rat
Attic Rat
Bergen Co.,N.J. USA
Posts: 524
Joined: December 2003
Show All Member Profiles 
Top Posters(30 Days)
sparky 10
Popular Topics(Views)
259,540 Are you busy
194,935 Re: Forum
184,367 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3