when did sub panels start requiring 4 wires ?

[Stevenfyeager]

I just got done running a 4 wire cable to a sub panel my dad ran in his house in 1978. (And I isolated the neutrals) He had run a 3 wire cable and we are getting ready to sell his house. A home inspector would've caught that. I'm assuming in 1978, the code was different ?

 

[infinity]

I would guess that the 4-wire feeder been part of the NEC for 80-90 years.

 

[Stevenfyeager]

I would guess that the 4-wire feeder been part of the NEC for 80-90 years.

wow

 

[Little Bill]

I would guess that the 4-wire feeder been part of the NEC for 80-90 years.

Not for a separate building. That was only changed in either the 05 or 08 code. There were some stipulations such as no metallic paths between buildings.

 

[yesterlectric]

In a number of old houses you find armored cable, which means that even if it was three wire single phase it could have still had an equipment ground and been practically 4 wire. The practice of doing that is still legal in most cases.

Are you sure that neutral and equipment grounds were connected together at the panel?

 

[jaggedben]

Recently I've been running into a surprising (to me) number of cables with no EGCs, both for branch circuits and feeders. It seems to date to the 1950s or 60s. I suspect that at the time it must have been permitted for the branch circuits because otherwise the 12awg cable would seemingly not have been compliant for any use. I'm less sure about the 100A feeders, since that cable might have been compliant for services or for certain appliances, and simply misused in the instances I've seen. I also know that statewide code adoption was in its infancy during those decades so as far as I know it's possible it was locally compliant but prohibited in the NEC at the time.

 

[ptonsparky]

It would have been wrong in ’78. I started business in 80 and had been doing 4 wire feeders well before that.

 

[DrSparks]

Not for a separate building. That was only changed in either the 05 or 08 code. There were some stipulations such as no metallic paths between buildings.

Yeah I remember that. No water pipes etc. It was wired like a service.

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[junkhound]

I just got done running a 4 wire cable to a sub panel my dad ran in his house in 1978. (And I isolated the neutrals) He had run a 3 wire cable and we are getting ready to sell his house. A home inspector would've caught that. I'm assuming in 1978, the code was different ?

Was it same code cycle that require 4 prong clothes dryer plugs? Don't recall year exactly, mid 90's IIRC.

 

[norcal]

Was it same code cycle that require 4 prong clothes dryer plugs? Don't recall year exactly, mid 90's IIRC.

3-wire ranges & dryers finally went away in the 1996 NEC. What would matter is when that edition was adopted.

 

[infinity]

Not for a separate building. That was only changed in either the 05 or 08 code. There were some stipulations such as no metallic paths between buildings.

True, but I didn't get a sense from the OP that this was a separate structure.

 

[James L]

I don't think I've ever seen a 4-wire feeder before 1970s. I think there was a long time, at least in this area, that it would have just been viewed as part of the service instead of a feeder

 

[Stevenfyeager]

True, but I didn't get a sense from the OP that this was a separate structure.

It was in the same structure, right next to the main panel.