Your opinion of existing 3 wire Dryers and Ranges on Sub panel

[brother]

I suppose this is more of a question for inspectors. A buddy of mine sent me a link to their states electrical Newsletter. Apparently the inspectors are requiring contractors to run new circuits for dryers and ranges when they only swapping or adding a panel and the existing panel becomes a subpanel. It was my understanding that as long as you didn't touch those existing branch circuits or didn't uncover over 50% of the wall you would not have to do that. Apparently some have been redtag on this.

What is your opinion of this? Does your area require you to rewire the dryer and stove when you only added a subpanel and didn't touch the existing branch circuits? This can be extra time consuming and extra money depending on how far and what crawling around you have to do to run that new 4 wire.

Here is what it says:

Changing an Existing 3-wire Service into a 4-wire Sub-Panel & Existing 3-Wire Circuits
Occasionally, inspectors encounter an existing service panel that has been modified into a 4-wire sub-panel. This may cause the existing 3-wire range and clothes dryer circuits to be out of compliance with NEC 250.140. When a service panel is modified to a 4-wire sub-panel, any existing 3-wire range or clothes dryer circuits are no longer compliant with 250.140, exception and must be modified to meet code. Code does not allow running a 4-wire feeder and re-bonding the equipment grounding conductor to the neutral downstream of the newly created sub-panel

 

[suemarkp]

One of the code requirements for the exception that allowed the grounded conductor to also be a grounding conductor is that the circuit must originate from a Service panel and not a sub panel. Changing the main panel to a sub makes it non-compliant with the original rule. See 250.140 Exception (3) -- "and the branch circuit originates at the service equipment."

I think that article was in the Washington Electrical Currents newsletter. Seems like a good call to me.

 

[GoldDigger]

I suppose this is more of a question for inspectors. A buddy of mine sent me a link to their states electrical Newsletter. Apparently the inspectors are requiring contractors to run new circuits for dryers and ranges when they only swapping or adding a panel and the existing panel becomes a subpanel. It was my understanding that as long as you didn't touch those existing branch circuits or didn't uncover over 50% of the wall you would not have to do that. Apparently some have been redtag on this.

What is your opinion of this? Does your area require you to rewire the dryer and stove when you only added a subpanel and didn't touch the existing branch circuits? This can be extra time consuming and extra money depending on how far and what crawling around you have to do to run that new 4 wire.

Given that the exception in 250.140 lists four conditions. all of which must be met, and condition 3 is as shown below [2011], I do not see any way of avoiding doing this in the face of that AHJ interpretation except to re-run the branch circuit to the new service panel. But in that case it would no longer be an existing circuit, and you are out of compliance anyway.

(3) The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service- entrance cable and the branch circuit originates at the service equipment.

HOWEVER:

Let A = the grounded conductor is insulated,
B = the grounded conductor is uninsulated,
C = the grounded conductor is part of a Type SE cable,
D = the branch circuit originates at the service equipment.

Like many of the code provisions, the simple sentence "A, or B and C and D" could either mean:

1. (A or (B and C)) and D [meaning not allowed to originate at a sub-panel, ever] or
2. A or (B and C and D) [meaning that if you have an insulated grounded conductor the branch circuit does not have to originate at the service panel]

The miniscule clue of the presence of only one comma, after A, tilts the argument slightly in the direction of the second interpretation IMHO.

I think that if the existing grounded conductor is uninsulated there is no interpretation that would allow the branch circuit to originate at a subpanel.
And adding an insulated conductor to the existing run would allow you to bring it totally into compliance except for the small issue of the grounded conductor not being part of the original cable assembly, but would probably not be any easier than replacing the whole branch circuit.

Does anybody have any explanatory material or CMP/ROP comments which could clarify the intent of that wording?

 

[brother]

One of the code requirements for the exception that allowed the grounded conductor to also be a grounding conductor is that the circuit must originate from a Service panel and not a sub panel. Changing the main panel to a sub makes it non-compliant with the original rule. See 250.140 Exception (3) -- "and the branch circuit originates at the service equipment."

I think that article was in the Washington Electrical Currents newsletter. Seems like a good call to me.

I see the part about the 'service equipment'. Must have missed that part. Well, it appears anytime one puts in a bid to do a panel change and have to put in a subpanel then there has to be a bid for the 2 circuits for the stove and dryer.

 

[norcal]

If the dryer circuit is 10/3 NM what would be the problem if fed from a subpanel? If the cable does not have a grounding conductor, leave it as-is, if it does the receptacle could be upgraded to 4-wire.

 

[GoldDigger]

If the dryer circuit is 10/3 NM what would be the problem if fed from a subpanel? If the cable does not have a grounding conductor, leave it as-is, if it does the receptacle could be upgraded to 4-wire.

Reread post #3.
Two possible interpretations of (3):
In one, the requirement is that in all cases the old branch circuit must originate in the service panel if there is no separate EGC present.
In the other, the origination requirement does not apply if the grounded conductor is insulated.
Which is correct?

 

[Little Bill]

Reread post #3.
Two possible interpretations of (3):
In one, the requirement is that in all cases the old branch circuit must originate in the service panel if there is no separate EGC present.
In the other, the origination requirement does not apply if the grounded conductor is insulated.
Which is correct?

The latter, it's been explained to me several times.
The neutral can be bare if part of an SE cable and originates in the main service panel.
An insulated neutral can originate in a sub panel.
This, of course is in old installations.

 

[iwire]

The latter, it's been explained to me several times.
The neutral can be bare if part of an SE cable and originates in the main service panel.
An insulated neutral can originate in a sub panel.
This, of course is in old installations.

That is incorrect, forever and always the NEC has required 3 wire range and dryer circuits to originate at the service panel.

 

[roger]

That is incorrect, forever and always the NEC has required 3 wire range and dryer circuits to originate at the service panel.

It has been a requirement since I started in the 70's

The wording in the 90 NEC (the oldest I have available at the moment) article section 250-6(c) is the same as it is in 250.140 Exception 3


Roger

 

[suemarkp]

That is incorrect, forever and always the NEC has required 3 wire range and dryer circuits to originate at the service panel.

Something that backs this up is mobile homes never allowed the 3 wire range/dryer connections (whether NM or SE cable), as they are usually "subpanels" in the mobile home. 550.16(A)(2) is where this is located now, but you'll probably find the same restriction many year back in the code.

 

[Little Bill]

That is incorrect, forever and always the NEC has required 3 wire range and dryer circuits to originate at the service panel.

You won't convince me I'm wrong when all the inspectors here read it the same as I do.
If they had meant for all of exception 3) to mean all three wire wire circuits had to originate at the service equipment, they would have put a comma after the word "cable". The way it is written it means if you use SE cable with bare neutral it has to originate at the service.

If you want it to mean what you believe, put in a proposal for a comma!

Exception: For existing branch-circuit installations only
where an equipment grounding conductor is not present in
the outlet or junction box, the frames of electric ranges,
wall-mounted ovens, counter-mounted cooking units,
clothes dryers, and outlet or junction boxes that are part of
the circuit for these appliances shall be permitted to be
connected to the grounded circuit conductor if all the following
conditions are met.
(1) The supply circuit is 120/240-volt, single-phase,
3-wire; or 208Y/120-volt derived from a 3-phase,
4-wire, wye-connected system.
(2) The grounded conductor is not smaller than 10 AWG
copper or 8 AWG aluminum.
(3) The grounded conductor is insulated, or the grounded
conductor is uninsulated and part of a Type SE service entrance
cable and the branch circuit originates at the
service equipment.
(4) Grounding contacts of receptacles furnished as part of
the equipment are bonded to the equipment.

 

[roger]

Posting to get to page 2

Roger

 

[GoldDigger]

If you want it to mean what you believe, put in a proposal for a comma!

That would be an RFC, right?

 

[Little Bill]

That would be an RFC, right?

RFC=request future comma

then yes!

 

[curt swartz]

I have always interpreted it to only require the circuit to originate at the service panel if the neutral is uninsulated. This is how every apartment, condo, townhouse and probably 50% of the single family dwellings are wired in California.

If the intent was to always require the 3-wire circuit to originate at the service panel why would this requirement be part of (3) instead of a separate line?
The requirements are:
(1) Insulated
or
(2) can be uninsulated if from the service panel

 

[Little Bill]

I have always interpreted it to only require the circuit to originate at the service panel if the neutral is uninsulated. This is how every apartment, condo, townhouse and probably 50% of the single family dwellings are wired in California.

If the intent was to always require the 3-wire circuit to originate at the service panel why would this requirement be part of (3) instead of a separate line?
The requirements are:
(1) Insulated
or
(2) can be uninsulated if from the service panel

That's the way I see it too.

If their intent was for all 3-wire circuits to originate at the service I don't see why they even bothered to mention insulated and uninsulated. Could have just said all 3-wire circuits must originate at the service and only SE cable would be allowed to be uninsulated.

 

[GoldDigger]

RFC=request future comma

then yes!

Actually, it would be a Request For Comma [Comment]?
With apologies to the IETF.

 

[brother]

Its interesting to see how the language and punctuation can have such a profound effect on this issue. I basically feel if there is not a real safety hazard with the subpanel, then I see no reason to force people to rewire the dryer and the kitchen.

Maybe the CMP needs to clarify that section of the NEC.

 

[mbrooke]

That is incorrect, forever and always the NEC has required 3 wire range and dryer circuits to originate at the service panel.

I disagree, from my take on the wording as long as its not a type SEU cable an insulated neutral can exist from a subpanel as grounding conductor downstream.


I have seen hundreds of condos and apartments with sub panels where a 3 wire circuit was used for either the range or dryer and it passed inspection. I also don't think I've ever seen a NEMA
14-30 or 14-50 in a residential minus a few mobile homes latter on pre 1997.

 

[mbrooke]

I have always interpreted it to only require the circuit to originate at the service panel if the neutral is uninsulated. This is how every apartment, condo, townhouse and probably 50% of the single family dwellings are wired in California.

If the intent was to always require the 3-wire circuit to originate at the service panel why would this requirement be part of (3) instead of a separate line?
The requirements are:
(1) Insulated
or
(2) can be uninsulated if from the service panel

That and nearly every single commercial install where you find a non grounding type twist lock or straight blade. In my area we have tons of older restaurants with cooking appliances that have a non grounding plug like a 208 steam warmer buffet, 208 for the heaters 120 for the lamps. Plug is something like a NEMA 18-20R or a twist lock run in conduit; insulated neutral coming from a sub panel. I think the reasoning behind not using an SEU in a sub in that the neutral is bare. Landing it on the neutral bar could cause it to also short against the can bypassing the separation in a subpanel.