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Blown Fuse = Service Replacement; Old Code Question #88512 06/14/04 11:02 AM
Joined: Jul 2003
Posts: 26
rlrct Offline OP
Homeowner's sitting in their weekend cottage and turns on the ceiling fan this past weekend. Fan suddenly stops working - blown fuse. Trace it to low voltage on 1 incoming leg (25 v). LOPOCO comes, pulls the meter. Sure 'nuff, one of the clips in the meter base wasn't tight enough and the connection heated. You can see the discoloration on the underground service lateral where the aluminum conductor heated up. Need to replace the meter base. It turns out the entire service through and including the panelboard will need to be replaced. Why?

The GES, which consists of (1) 1/2" ground rod and a single armored grounding wire (looks like #10), is bonded to the meter base. From the meter, SE cable runs to a 100 amp disconnect. From there, old SE cable runs to the original, screw-in fuse panelboard. There is an unfilled hole in the fuse panel for the original service disconnect where the panel was "converted" from 3-wire service equipment to a 3-wire subpanel. There is an armored grounding cable that runs to the copper water pipe where it's attached within 5' of the water service entrance with a standard, tagged and labelled, clamp. Unfortunately, that conductor to the water pipe is only satisfying 250.104, because about a foot to the right of the clamp, the copper transitions to PVC where it's PVC to and through the foundation.

So, we have:
  • a 100-amp service, with
  • a panelboard with no isolated ground which should be 4-wire,
  • fed by SE cable with no grounded conductor,
  • where the uninsulated grounding conductor is current carrying and connects to
  • a GES which is undersized for the service.

BTW, loads include electric range with double oven, hot water heater and dryer.

Was it ever code-compliant to run just a 3-wire feed from the SD to a panelboard, where the bonding was at/before the SD? Sort of doesn't matter, because the whole mess is being corrected now, but I am curious about the code from the early 1970's when this was done.


[This message has been edited by rlrct (edited 06-14-2004).]

[This message has been edited by rlrct (edited 06-14-2004).]

2017 / 2014 NEC & Related Books and Study Guides
Re: Blown Fuse = Service Replacement; Old Code Question #88513 06/14/04 01:33 PM
Joined: Mar 2001
Posts: 345
tdhorne Offline
If the service disconnectting means is not located in or on the building were that panel is mounted it would still be lawful today to run a three wire cable as the feeder as long as there are no parallel conductve paths betwen the two locations.
Tom H

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
Re: Blown Fuse = Service Replacement; Old Code Question #88514 06/14/04 01:41 PM
Joined: Jul 2003
Posts: 26
rlrct Offline OP
This is a single family residence. The service disconnect is on a basement wall (within 5' of the meter). The panelboard is about 12' away on another basement wall.

Re: Blown Fuse = Service Replacement; Old Code Question #88515 06/14/04 06:19 PM
Joined: Dec 2003
Posts: 751
earlydean Offline
In my experience it never has been allowed by code.

Re: Blown Fuse = Service Replacement; Old Code Question #88516 06/15/04 03:04 PM
Joined: Mar 2004
Posts: 46
andyp95 Offline
IMO the service disconnect should be considered the main,and the 12' away panelboard should be considered a subpanel and be fed with a 4 cond. cable i.e. SER with a bonded ground bar and a seperate isolated nuetral bar.


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