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We recently purchased a new home that has a 16 x 30 steel building in the back yard approximately 100ft from the main panel. The building has power run to it off a 60 amp breaker in the main panel. The current sub panel is an old fuse box that desperately needs an upgrade. It appears that at some point a previous owner started to upgrade the electrical but never finished. There are three #2 aluminum feeders 2 hot and one neutral but no ground. I am going to replace the sub panel with a new GE panel and want to know the proper way to add a ground. Can I just run #4 wire from the panel to two grounding rods outside of the building or do I need to run a new wire back to the main?

The big reason I'm asking is that if I am going to pull a new wire I'm going to end up redoing the whole feed with a larger wire so that I can run a 125 amp sub panel. The building will eventually become my new shop with power hungry equipment. If I can safely get it up and running now for a minimum of expense that would be great otherwise I will have to plan for the larger project. Thanks for the advice.

Shawn in New Orleans

  • How long ago was this installed? Prior to 2008? Also don't bother fitting the ground rod, that is NOT a substitute for a proper ground. – Harper Mar 8 '18 at 21:28
  • I was told post Katrina so sometime after 2006 but couldn't be certain. I assumed I was going to have run the additional wire just don't really want to. All the wiring inside the building is newer Romex. It seems like they did everything but replace he panel. I have no idea why. – Shawn Hardy Mar 8 '18 at 22:08
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    Sounds like they limbo'd under the Code requirement which happened in NEC 2008 and was ratified a year or two later depending on jurisdiction. That was foolish and cheap; the change was not a surprise and was done for very good reasons. – Harper Mar 8 '18 at 22:16
  • Is the feeder run as a direct bury cable or pulled through conduit? – ThreePhaseEel Mar 8 '18 at 23:27
  • The 3 feeders are run through 1 1/4" PVC – Shawn Hardy Mar 8 '18 at 23:46
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Since it is an existing installation you don't need the ground wire until you upgrade it.

Your inspector may even allow you to use the 3-wire method with the new panel until you replace the wiring.

Fuse panels are not necessarily obsolete until they are no longer serviceable.

You could use it as-is unless you have the need for more than 60 amps right away. If it is working fine now don't be in a big hurry to spend your money.

Good luck!

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