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sub panel - 3 wires


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Anyone know what year they required sub panels to have four wires (hots, ground & neutral) and neutrals and grounds to be on separate bars?

Inspected a 1956 house that had a new sub panel (not sure of the year but in the last 15 years for sure). I would think that the new sub panel would be required to have the separate ground and neutral wires from the main panel right? Can't imagine how they would get around the requirement here (other issues in the box as well).

Two separate questions. Thanks.

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There are exceptions for "existing premises wiring systems only" that might apply. See 250.32(B)(1). I don't think you have to replace old existing wire just because the sub-panel itself is newer. But it depends on some conditions.

Now if they did run new wire, then definitely, they would need 4-wires. (I don't know when that became code.)

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There are exceptions for "existing premises wiring systems only" that might apply. See 250.32(B)(1). I don't think you have to replace old existing wire just because the sub-panel itself is newer. But it depends on some conditions.

Now if they did run new wire, then definitely, they would need 4-wires. (I don't know when that became code.)

Thanks. It is old wire.

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That panel is fairly new. Newer then 15 years thats for sure.

I'll bet it's no older then 8 or maybe 5 years.

I see incorrect breakers, multiple neutrals per terminal, grounds and neutrals on the same bterminal bar.

I am going to say that if you are replacing the panel, you must install it to the code in force at the time of installation. That means the feeder cable must be correct also, both in size and number of conductors.

Using the old cable that does not meet the code when the panel was installed, means that the panel can not be up to code either.

So yes the feeder cable shall be replaced !! Leaving like it is creates a dangerous situation, a possible deadly situation.

By having the neutral bonded down to the panel, you have created a parallel path for the neutral currents.

Grounds are not designed to carry current, thats why they can be bare.

Neutrals DO carry current back to the source. By having the neutral bonded to the panel can you have now allowed those neutral currents to flow on the exposed metal can, the metal panel cover, and any thing else that is grounded,( water pipes and such) In a fault there can be an extremely large amount of current going across those metal parts.

be Smart and cover you r butt- Call it out as dangerous and incorrect.

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There are exceptions for "existing premises wiring systems only" that might apply. See 250.32(B)(1). I don't think you have to replace old existing wire just because the sub-panel itself is newer. But it depends on some conditions.

Now if they did run new wire, then definitely, they would need 4-wires. (I don't know when that became code.)

the existing premise wiring exception is for branch circuit wiring for receptacles. You are allowed to replace receptacles on a 2 wire ( ungrounded) circuit IF you use the proper devices. When replacing receptacles on 2 wire circuits you need to use either a non grounding receptacle or a gfci receptacle and label it as no equipment ground.

Tha exception does not cover feeders to a sub panel as there is a real life threatening situation created by doing so.

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A GFCI outlet device is an improvement over an ungrounded outlet but it doesn't prevent a voltage spike, such as might be generated by a lightning bolt striking the power line, from passing through unscathed and damaging expensive personal property such as TV's, computers, etc. Surge devices installed on ungrounded branch circuits would offer only the appearance of surge protection since they use varisters to bypass the energy of the spike directly to ground via the grounding connection. No ground...no protection from spikes. Today's codes require grounding and bonding. That should be sufficient justification for us to recommend that grounding be installed, unless we're going to offer the client an inspection that is as old as the house.

Just my thoughts, is all.

Marc

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Anyone know what year they required sub panels to have four wires (hots, ground & neutral) and neutrals and grounds to be on separate bars?

1923.

There were exceptions for dryers & ranges and for separate buildings, but those exceptions went away in 1996 & 1999.

Inspected a 1956 house that had a new sub panel (not sure of the year but in the last 15 years for sure). I would think that the new sub panel would be required to have the separate ground and neutral wires from the main panel right? Can't imagine how they would get around the requirement here (other issues in the box as well).

That's the sort of thing for which the AHJ might make an exception. However, yes, if someone were actually to follow the rules, a sub panel from that time period would certainly have needed a 4-wire feeder unless it was in a different building.

- Jim Katen, Oregon

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There are exceptions for "existing premises wiring systems only" that might apply. See 250.32(B)(1). I don't think you have to replace old existing wire just because the sub-panel itself is newer. But it depends on some conditions.

Now if they did run new wire, then definitely, they would need 4-wires. (I don't know when that became code.)

the existing premise wiring exception is for branch circuit wiring for receptacles. You are allowed to replace receptacles on a 2 wire ( ungrounded) circuit IF you use the proper devices. When replacing receptacles on 2 wire circuits you need to use either a non grounding receptacle or a gfci receptacle and label it as no equipment ground.

Tha exception does not cover feeders to a sub panel as there is a real life threatening situation created by doing so.

Huh?

250.32 Buildings or Structures Supplied by Feeder(s) or

Branch Circuit(s).

That is not "for branch circuit wiring for receptacles". The exceptions do apply to feeders to a sub-panel, even if they may not be applicable in this particular case.

The OP asked a specific question and I pointed him to code that MIGHT apply depending on the location of the sub-panel and if other conditions were met. Clearly they are not (no GEC, etc), but he stated there were other known issues in the box.

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I read the original post as having the subpanel in the same structure/building as the main(service) panels is located in.

That being the case article 250.32 does not come into play as that is for a separate buildings / structures.

Article 250.32 (A) - tells us that buildings or structures fed by a feeder or branch cicuits SHALL have a grounding electrode OR a Grounding electrode system. This means a ground wire ran with the feeder or a grounding electrode system installed as per article 250.50.

The ONLY exception to this is when a single branch circuit is ran to the structure.

The original post shows neither of these.

So either way there must be a grounding electrode conductor or a equipment grounding conductor

The original post shows neither of these

Also don't forget, the feed to a sub panel is a FEEDER

Article 215 tells us about Feeders.

215.12 tells us about Identification for Feeders

215.12(A) Grounded Conductor (neutral) The grounded conductor of a feeder SHALL be identified in accordance with 200.6

200.6 Tells us that the grounded conductor (neutral) needs to be INSULATED.

The original post shows a BARE grounded conductor (neutral)

So that install is incorrect on a multitude of different levels.

NO grounding Conductor ( or ground electrode conductor if in a separate structure)

The use of a bare grounded conductor

Grounding conductors and grounded conductors in the same terminal

Multiple grounded conductors in the same terminal

incorrect circuit breakers

I can tell by the picture, but if that main back fed breaker is a snap in and is not held in place by a fastner that requires other then a pull to release it, it needs to have one installed according to article 408.36

I would also question the size of that grounded conductor, looks small to me but it may not be.

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Article 250.32 (A) - tells us that buildings or structures fed by a feeder or branch cicuits SHALL have a grounding electrode OR a Grounding electrode system. This means a ground wire ran with the feeder or a grounding electrode system installed as per article 250.50.

The ONLY exception to this is when a single branch circuit is ran to the structure.

Jack, This would be a ground rod or some other form of electrode, not a grounding conductor run with the feeder. The ground rod would be required regardless, unless the outbuilding is served by a single circuit. This would apply whether the feeder was a 3 or 4 wire.

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