2-2-4-SEU for Garage subpanel

[BTSaw]

I think electrician installed 2-2-4 SEU cable between the house 200A service panel and detached garage 100A subpanel. I think it should be 2-2-2-4 cable instead of 2-2-4. I can’t confirm because I’m out of town. Can someone site the NEC section stating a 4-conductor cable is necessary, so I can confront electrician and get him change it. Does it matter if it’s SER or SEU cable?

 

[Speedy Petey]

Do you not believe what folks here are saying?
http://www.diychatroom.com/f18/2-2-4-seu-smaller-neutral-157486/

 

[walrus]

I think electrician installed 2-2-4 SEU cable between the house 200A service panel and detached garage 100A subpanel. I think it should be 2-2-2-4 cable instead of 2-2-4. I can’t confirm because I’m out of town. Can someone site the NEC section stating a 4-conductor cable is necessary, so I can confront electrician and get him change it. Does it matter if it’s SER or SEU cable?

How did he run SEU to a detached building? Depends on what code you are on if 3 wire or 4 wire

 

[Speedy Petey]

Depends on what code you are on if 3 wire or 4 wire

The allowance for a "3-wire" feeder was removed several code cycles ago. I highly doubt a recent 3-wire installation would have been complaint.

 

[pattenp]

The required 4th conductor is the equipment ground. I believe 2005 was the year the code changed to 4 from 3 for 240V feeds.

2011 NEC 250.32 (B) (1) An equipment grounding conductor is to run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrodes.

 

[wyliesdiesels]

I think electrician installed 2-2-4 SEU cable between the house 200A service panel and detached garage 100A subpanel. I think it should be 2-2-2-4 cable instead of 2-2-4. I can’t confirm because I’m out of town. Can someone site the NEC section stating a 4-conductor cable is necessary, so I can confront electrician and get him to change it. Does it matter if it’s SER or SEU cable?

A 4-wire feeder is required between buildings(NEC 250.32B1) when there is other metal/grounding paths between the buildings. If there is no other "conductive" path between the buildings, then there is an exception and a 3-wire feeder is allowed.(NEC 250.32B1,2)

So, is there other metal pathways between the buildings(i.e. water or gas pipe, conduit, etc.)?

 

[BTSaw]

Thanks for the response and NEC info. It's exactly what I needed.

 

[Speedy Petey]

If there is no other "conductive" path between the buildings, then there is an exception and a 3-wire feeder is allowed.(NEC 250.32B1,2)

And this exception was removed after the 2005NEC.

 

[pattenp]

You may want to check with your local electrical inspector. In my area they require the 4 conductors regardless. I guess the feeling is you never know if some other conductive path may be made in the future.

 

[pattenp]

And this exception was removed after the 2005NEC.

My brain gets a little twisted when I read the exception clause as to what it's really saying. But unless the wording has changed that exception is still in the 2011. 250.32 (B) (1) (2) There are no continuous metallic paths bonded to the grounding system in each building or structure involved.

 

[walrus]

The allowance for a "3-wire" feeder was removed several code cycles ago. I highly doubt a recent 3-wire installation would have been complaint.

You can highly doubt anything you want, but my understanding is some areas are still on 99 and some areas don't accept every code in the NEC.My state Maine doesn't. So unless you know what code he is on...............

 

[BTSaw]

I don't have any metal conductors between the house and detached garage. Water line is PEX, electrical conduit is gray pvc, do not have a gas line. Thanks for the responses.

 

[wyliesdiesels]

The allowance for a "3-wire" feeder was removed several code cycles ago. I highly doubt a recent 3-wire installation would have been complaint.

Whoops! I guess its time to get a new code book! Mine is 2005!

The required 4th conductor is the equipment ground. I believe 2005 was the year the code changed to 4 from 3 for 240V feeds....

It must have changed in '08 because my code book is '05 and its in there!

 

[Speedy Petey]

My brain gets a little twisted when I read the exception clause as to what it's really saying. But unless the wording has changed that exception is still in the 2011. 250.32 (B) (1) (2) There are no continuous metallic paths bonded to the grounding system in each building or structure involved.

Read it carefully.

(B) Grounded Systems.

(1) Supplied by a Feeder or Branch Circuit. An equipment grounding conductor, as described in 250.118, shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).

Exception: For installations made in compliance with previous editions of this Code that permitted such connection, the grounded conductor run with the supply to the building or structure shall be permitted to serve as the ground-fault return path if all of the following requirements continue to be met:
........continued...

They are referring to exiting installations in that they do not have to be retrofitted.

 

[Speedy Petey]

You can highly doubt anything you want, ............

And I certainly will.

 

[pattenp]

Read it carefully.

They are referring to exiting installations in that they do not have to be retrofitted.

Yeah.. after posting my brain twisted comment I went back and read that section through a couple of times and then realized it was referring to existing 3 wire installs under previous code. I was reading something else into it.

 

[hidollartoys]

The main issue here is the OP stated the conductors were for a "sub-panel" and the garage is detatched. Which in all cases requires 4 wires.

 

[sberry]

Even if it was legal and you were under old code its still not a good idea to feed 3 wire.

 

[Speedy Petey]

The main issue here is the OP stated the conductors were for a "sub-panel" and the garage is detatched. Which in all cases requires 4 wires.

I think the point is that previous codes DID allow a "3-wire" feeder to a detached structure under the right circumstances.

 

[hidollartoys]

The OP was written in a way that would indicate this is new work.

Maybe BTSaw could/should specify weither it is new or old work.

 

[Speedy Petey]

The OP was written in a way that would indicate this is new work.

Maybe BTSaw could/should specify weither it is new or old work.

The thread on the other forum was just as confusing.

 

[BTSaw]

The house is unconstruction and detached garage is 95% complete.

Not to confuse the topic, but what if I installed a subpanel in my house off of my service panel, is SER 4 conductor cable required too?

 

[Speedy Petey]

Not to confuse the topic, but what if I installed a subpanel in my house off of my service panel, is SER 4 conductor cable required too?

Yes.

 

[pattenp]

Branch or Feeder circuits past the first main disconnect require an equipment grounding conductor. So if you add a 120V branch/feeder you'd need 3 conductors (Hot, Neutral, EG). If you add a 240V branch/feeder you'd need 4 conductors (Hot, Hot, Neutral, EG). You can change the 2-2-4 feeder to 120V and mark one of the #2 conductors as neutral(white) and that would make it code compliant but I'm sure that's not what you want to do.

 

[wyliesdiesels]

The house is unconstruction and detached garage is 95% complete.

Not to confuse the topic, but what if I installed a subpanel in my house off of my service panel, is SER 4 conductor cable required too?

Hopefully, the walls are still open in the garage(I doubt it being 95% done) then it will be easier to change. Otherwise, its on his dime to redo the rock and paint and of course pay for the cable! But, u should check with your building department and see what code cycle they're on and as to whether it will pass! If they're on NEC 2005, then 3-wire is allowed. But, if it were mine, I would still do a 4-wire SER regardless of what code cycle my town was on!

And ditto to what pattenp said about sub-panels and 4 wire feeders!