3 WIRE SUB PANEL UPGRADE

[Jazzman]

A couple of years ago I pulled a permit and installed a new 4 wire 60 amp sub panel to my well house for new submersible pump. My barn/shop which is located about 25’ away was wired in the 90’s and only has a 3 wire(no ground) service. Would bringing a ground wire from well house sub panel to barn meet code for current 4 wire requirements? Otherwise, house is over 100’ away.

Thanks

 

[wwhitney]

No, not a good idea, and the grounding wire in a 60 amp feeder is likely too small for a 100A feeder.

As we discussed, if there's no other metallic path between the barn and house, there's nothing really wrong per se with your existing 3 wire feeder. I expected the 4 wire feeder requirement is mostly about providing a solution that is more robust, in case there are other metallic paths.

Cheers, Wayne

 

[Sponsor]

 

[Jadnashua]

Look at it this way...neutral and ground are tied together back at the main panel and likely the transformer supplying it. Ground is not supposed to carry any current. But, most metal bits are bonded to the ground wire to provide an alternate path to ground should a hot wire accidentally touch something it shouldn't, providing an alternate path to ground to either blow the fuse or trip the circuit breaker protecting that circuit. Without a ground wire, if there's a fault, it provides a layer of safety. It can also help if there's a nearby lightning strike.

There are probably millions of older stoves and dryers out there without a ground connection using a 3-wire plug/connector. They rarely hurt someone unless the insulation gets damaged. It's safer if there's a ground connection.

 

[wwhitney]

Just want to chime in that most of the function of the EGC has to do with bonding to provide a low current fault path back to the supply neutral conductor, and very little of it has to do with connecting to earth. It would really be clearer if we didn't use the word "ground" and used the terms "bond" and "earth" as appropriate; this would avoid the mistaken idea that "current wants to return to ground." In the previous post, the word ground should be read as "bonding conductor" except for the bit about the transformer and the bit about lightning.

Cheers, Wayne

 

[Jazzman]

Thanks for you replies gentlemen! I guess I’m better off leaving well enough alone. However, both sub panels are rated for 60 amps if that was to make a difference. I think ground wire was a #10 in pump house sub panel.