Upgrading 3 wire SE system to 4 wire

[egwmiv]

Hello! I've been scouring my code book and cant find a specific answer to my issue. When upgrading an existing 3 wire system with a separate service disconnect current code require an EGC run to the breaker panel (which is considered a sub-panel). My question is, if there is an existing 3 conductor bundle (SER cable), is it permissible to run a separate EGC conductor? Our local AHJs are insisting that a new 4 conductor bundle be run in lieu of adding the single conductor. Can anyone point out where NEC deals with this?

Thanks in advance!

 

[petersonra]

Hello! I've been scouring my code book and cant find a specific answer to my issue. When upgrading an existing 3 wire system with a separate service disconnect current code require an EGC run to the breaker panel (which is considered a sub-panel). My question is, if there is an existing 3 conductor bundle (SER cable), is it permissible to run a separate EGC conductor? Our local AHJs are insisting that a new 4 conductor bundle be run in lieu of adding the single conductor. Can anyone point out where NEC deals with this?

Thanks in advance!

300.3(B) generally you have to run the EGC within the same cable.

It might help if you drew a sketch of what is there and another sketch of what you want to accomplish because your description is a little confusing to me.

Service conductors don't need an egc.

If you are adding an outside disconnect as required by the 2020 code, I think there is a special rule that might allow this without an egc, but I do not have a copy of the 2020 code.

 

[GoldDigger]

egwmiv, your occupation lists Sales.
Are you a salesman for an electrical contractor? Is the sytem being upgraded yours or a customers?
Our Forum rules do not allow us to assist DIY users.

 

[egwmiv]

egwmiv, your occupation lists Sales.
Are you a salesman for an electrical contractor? Is the sytem being upgraded yours or a customers?
Our Forum rules do not allow us to assist DIY users.

GD, I do work for a contractor, we do generator install, sales and service. I do the estimating and project management.

 

[egwmiv]

300.3(B) generally you have to run the EGC within the same cable.

It might help if you drew a sketch of what is there and another sketch of what you want to accomplish because your description is a little confusing to me.

Service conductors don't need an egc.

If you are adding an outside disconnect as required by the 2020 code, I think there is a special rule that might allow this without an egc, but I do not have a copy of the 2020 code.

The specific project is adding 2 Non-SE ATS' to a 400 amp system that has service disconnects feeding 2 main panels. The existing wire is a 3 wire SER run in a crawlspace. We will need to bring the system up to code and upgrade to 4 wire if we install the ATS's. In order to replace the existing wire with a new 4 wire SER, it would mean running two 60ft sections of new SER cable, which isn't cheap these days. But the right way to do it isn't always the cheapest or easiest

 

[tortuga]

... We will need to bring the system up to code and upgrade to 4 wire if we install the ATS's. In order to replace the existing wire with a new 4 wire SER, it would mean running two 60ft sections of new SER cable, ...

Thats correct.
Also watch out for 3-wire ranges and dryers, if they are the old NEMA 10-50 style they might also need to converted to 4-wire, because altering a service to a sub panel you loose the exception under 250.140.

 

[don_resqcapt19]

In general, the rule in 300.3(B)(3) will let you run the EGC along side the existing SE cable. 300.11(D) will not permit you to use the SE cable to support the added EGC.

 

[tortuga]

In general, the rule in 300.3(B)(3) will let you run the EGC along side the existing SE cable.

Where do you get that?
300.3(B)(3) references 250.130(C) which only applies to branch circuits.
250.134 Ex 2 (DC circuits)
and 250.102(E) Bonding conductors.

 

[wwhitney]

300.3(B)(3) references 250.130(C) which only applies to branch circuits.

Isn't that 300.3(B)(2) "Grounding and Bonding Conductors"? 300.3(B)(3) is "Nonferrous Wiring Methods".

Cheers, Wayne

 

[tortuga]

Isn't that 300.3(B)(2) "Grounding and Bonding Conductors"? 300.3(B)(3) is "Nonferrous Wiring Methods".

Cheers, Wayne

Right thanks type'o
Upon further thought a bonding conductor and a EGC are the same thing per the definitions so the 250.102(E)(2) might apply but thats limited to 6 feet.
Then if its existing SE cable you have the bare neutral to deal with..

 

[wwhitney]

Right thanks type'o
Upon further thought a bonding conductor and a EGC are the same thing per the definitions so the 250.102(E)(2) might apply but thats limited to 6 feet.

But Don was referencing 300.3(B)(3), which is for any non-ferrous wiring method. Which would include SE cable. So the EGC could be run in a separate non ferrous wiring method, alongside the existing SE cable.

Cheers, Wayne

 

[don_resqcapt19]

The section I cited acts as an exception to the main rule, as explained by Wayne in post 11.

 

[tortuga]

Duha thanks
Please excuse me as I bang my head on the wall.

 

[kwired]

But Don was referencing 300.3(B)(3), which is for any non-ferrous wiring method. Which would include SE cable. So the EGC could be run in a separate non ferrous wiring method, alongside the existing SE cable.

Cheers, Wayne

Yes, but:

Right thanks type'o
Upon further thought a bonding conductor and a EGC are the same thing per the definitions so the 250.102(E)(2) might apply but thats limited to 6 feet.
Then if its existing SE cable you have the bare neutral to deal with..

You can't really use that bare conductor in the existing SE cable for anything but an EGC on load side of the service disconnecting means.

 

[wwhitney]

You can't really use that bare conductor in the existing SE cable for anything but an EGC on load side of the service disconnecting means.

That sounds right although the citation is escaping me. But then you can just run an insulated neutral in a separate non ferrous wiring method, alongside the existing SE cable.

Cheers, Wayne

 

[LarryFine]

How about a single-conductor SER?

 

[Fred B]

Is there a prohibition to putting the ATS inside next to the existing panel if access to pulling new service wire is prohibitive? (Don't have my code book with me.)Then you connect your 4wire from there. Of course that then might require longer gen cable.

The specific project is adding 2 Non-SE ATS' to a 400 amp system that has service disconnects feeding 2 main panels. The existing wire is a 3 wire SER run in a crawlspace. We will need to bring the system up to code and upgrade to 4 wire if we install the ATS's. In order to replace the existing wire with a new 4 wire SER, it would mean running two 60ft sections of new SER cable, which isn't cheap these days. But the right way to do it isn't always the cheapest or easiest

Sounds like maybe the existing system was not compliant to begin with, (feeders from the 400A with disconnects to the seperate panels should already have been 4 conductors.) now your left with fixing it. Sounds like a change order to me.
Everything after that first disconnect is no longer service conductors, but feeder conductors.
Perhaps 215,225 or 230 has your answer.

 

[kwired]

Is there a prohibition to putting the ATS inside next to the existing panel if access to pulling new service wire is prohibitive? (Don't have my code book with me.)Then you connect your 4wire from there. Of course that then might require longer gen cable.


Sounds like maybe the existing system was not compliant to begin with, (feeders from the 400A with disconnects to the seperate panels should already have been 4 conductors.) now your left with fixing it. Sounds like a change order to me.
Everything after that first disconnect is no longer service conductors, but feeder conductors.
Perhaps 215,225 or 230 has your answer.

I agree, don't think what was there was compliant in the first place as it appears to be feeders and not service cables so should have had EGC's to begin with.

 

[tortuga]

Sounds like maybe the existing system was not compliant to begin with, (feeders from the 400A with disconnects to the seperate panels should already have been 4 conductors.)

Good catch