When to replace electrical feeders?

[Mevlevi]

We are replacing Federal Pacific panels in a building built in 1970. Should the feeders also be replaced? Is the decision based on number of years in service? Testing?

 

[ptonsparky]

What is being changed besides the panels? Are bonding and grounding up to today’s standards? Meg the conductors, look at the instal. Clean and neat or a cluster?

 

[LarryFine]

I wouldn't replace wire based on age alone.

 

[Peter Furrow]

What wiring method was used for the feeders to the panel?
Is it a 3-wire service entrance cable?
Does the panel you’re replacing have two hots, neutral and grounding..?


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[Mevlevi]

What is being changed besides the panels? Are bonding and grounding up to today’s standards? Meg the conductors, look at the instal. Clean and neat or a cluster?

It is a commercial building. Wiring is 3P, 4W with the conduit used as ground. The main switchboard was replace 5 years ago, together with GEC. Minimal additions to the branch circuits over the years. The wiring is neat.

 

[Mevlevi]

I wouldn't replace wire based on age alone.

Ok. What criteria would you use to recommend either keeping the wiring or replacing the feeders?

 

[ptonsparky]

Ok. What criteria would you use to recommend either keeping the wiring or replacing the feeders?

See your post 5.

 

[Mevlevi]

What wiring method was used for the feeders to the panel?
Is it a 3-wire service entrance cable?
Does the panel you’re replacing have two hots, neutral and grounding..?


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Wiring is in conduit. It partially runs under slab and rises up in a chase. Panel has 3 hots, neutral and the conduit is used as EGC.

 

[ptonsparky]

And have the feeders tested.

 

[Peter Furrow]

Wiring is in conduit. It partially runs under slab and rises up in a chase. Panel has 3 hots, neutral and the conduit is used as EGC.

The metallic conduit serves as an equipment grounding conductor and is embedded in the slab. Us beachside electricians in Florida have seen countless buildings and condominiums where the equipment grounding conductor is lost because of rusted metallic conduit in the slab. I would test the equipment grounding in the feeders to the panels. Of course you know you have to separate your equipment grounding and your neutrals in the panel.
But if there’s not an effective ground fault current path in the feeders from the panel back to the main that could be a problem..


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[kwired]

I wouldn't replace wire based on age alone.

Did you feel that way before you had some age on yourself?

JK, I probably wouldn't either. 1970 probably used THW conductor. Thicker insulation might be as good or better than THHN/THWN especially if subject to same abuse during installation.

 

[ptonsparky]

The under slab conduit would be bothersome to me.