Can I install a larger breaker than the feed breaker in a subpanel?

[GoldDigger]

I do not.
If the device does not adequately protect the conductor then it is not an OCPD for those conductors and for all practical purposes does not exist. The 30A breaker is the branch circuit breaker.

But if the OP installs 50A conductors, then the 50A breaker becomes a branch breaker? OK.

 

[jaggedben]

For those who think it is illegal. Would you also say it is illegal feed a sub panel in your garage that is main lug only with 60 amps and put 10 20 amp breakers in it? Because it is not.

No, because each circuit - the feeder and the branch circuits - are properly protected at their rating and point of supply.

Also, how about if I put a subpanel in my shop, w/ a 100 A breaker as the disconnect, but use a 90 amp breaker in the main panel feeding it, since the ampacity of the wire feeding it doesn't support 100 A.

All good. Although it makes no pratical difference in most situations, I'd say the code requires the 90A breaker to be at the point of supply. So if you switched their locations, I'd say that's wrong.

Note that if someone taps the feeder to install a solar inverter output, you'd be required to downsize the 100A at the shop to a 90A. (705.12(D), 2014 code)

So basically he has a correctly wired 30 amp circuit but the addition of a GFCI device into the circuit has caused an NEC violation.

I am not seeing the logic in this in the least and I don't believe that is what 240.21 is restricting.

There's two circuits here; a feeder and a branch circuit. If he had not mentioned that the 50A breaker is in a subpanel, then I wouldn't say there's a violation. But when you put distribution in the middle of a circuit then the upstream conductors are no longer the branch circuit, they're a feeder.

I do not.
If the device does not adequately protect the conductor then it is not an OCPD for those conductors and for all practical purposes does not exist. The 30A breaker is the branch circuit breaker.

Even though the 30A is the breaker for a feeder supplying a subpanel?? I'm gonna believe you just missed that part.

The NEC generally addresses the current installation, what someone may do in the future is not typically a factor (e.g. there is nothing in Section 240 that deals with preventing a protective device from being changed)

There are a lot of sections of the code (e.g. marking and grouping) that are aimed at ensuring that the next guy can figure out what's going on and not need an original set of plans to avoid screwing things up. I'd say that putting the proper size breaker where the branch circuit begins is just of a piece with that.

 

[jim dungar]

There's two circuits here; a feeder and a branch circuit. If he had not mentioned that the 50A breaker is in a subpanel, then I wouldn't say there's a violation. But when you put distribution in the middle of a circuit then the upstream conductors are no longer the branch circuit, they're a feeder.

The NEC does not use the term 'subpanel'.
Whether the 30 A is a feeder or a branch OCPD is immaterial. The only issue is if the 30A conductors after the 50A GFI are adequately protected.
The NEC does not prevent an OCP from serving as both a feeder and a branch circuit protective device at the same time.

 

[jim dungar]

There are a lot of sections of the code that are aimed at ensuring that the next guy can figure out what's going on(e.g. marking and grouping)...

Then simply mark the 50A as being for GFI protection only.

...and not need an original set of plans to avoid screwing things up.

Actually most codes and standards require accurate one-lines rather than simply marking.

 

[jaggedben]

The NEC does not prevent an OCP from serving as both a feeder and a branch circuit protective device at the same time.

Sure it does. The feeder and the branch circuit are different circuit conductors.

 

[petersonra]

Sure it does. The feeder and the branch circuit are different circuit conductors.

how about a service where there is just one load and the service OCPD directly feeds that load?

 

[donaldelectrician]

Then simply mark the 50A as being for GFI protection only.


Actually most codes and standards require accurate one-lines rather than simply marking.

Can you use a different cb to provide the GFI circuit protection ? A 50A instead of the required 30A gfci ?




Don

 

[ActionDave]

Can you use a different cb to provide the GFI circuit protection ? A 50A instead of the required 30A gfci ?




Don

In the scenario being discussed I say yes.

Do I ever expect myself to? No.

 

[jaggedben]

how about a service where there is just one load and the service OCPD directly feeds that load?

That service doesn't have any feeders.

I don't get what's difficult to understand about that.

 

[ActionDave]

Sure it does. The feeder and the branch circuit are different circuit conductors.

And the only requirement for either is they be protected adequately.

 

[donaldelectrician]

But if the OP installs 50A conductors, then the 50A breaker becomes a branch breaker? OK.

Most probably the Manufacture calls for a 30A GFCI CB to protect the circuit , not a 50A GFCI .

That would be my objection .





Don

 

[iwire]

There's two circuits here; a feeder and a branch circuit. If he had not mentioned that the 50A breaker is in a subpanel, then I wouldn't say there's a violation. But when you put distribution in the middle of a circuit then the upstream conductors are no longer the branch circuit, they're a feeder.

I disagree with your opinion here.

The NEC does not distinguish a branch circuit from a feeder due to the installation of a subpanel in this case the subpanel contains a GFCI device not branch circuit OCPD.

The branch circuit OCPD is back at the main panel.

 

[jaggedben]

And the only requirement for either is they be protected adequately.

They must be protected at the point of supply. Interpret that how you will, but it's more specific than 'adequately.'

I disagree with your opinion here.

The NEC does not distinguish a branch circuit from a feeder due to the installation of a subpanel in this case the subpanel contains a GFCI device not branch circuit OCPD.

The branch circuit OCPD is back at the main panel.

Having reviewed the definitions, I agree with you unless or until someone puts another load (or source) into the subpanel. They make enclosures that are designed for a single circuit breaker; the OP would do well to use such a one if the intent is that it serves only as a place to insert the GFCI device into the branch circuit. In that case I'd drop my objections.

 

[GoldDigger]

Just to add another off the wall "what if?":
If you add s PV backfeed breaker in the subpanel, then the 30A feeder breaker no longer protects the branch circuit to the level the load requires.

 

[jim dungar]

....The feeder and the branch circuit are different circuit conductors.

There are many situations with booster and lubricating pumps where they are fed from the main motor circuit protective device.
What about almost every control power transformer or surge protective device?

A conductor used as both a feeder and a branch circuit must meet both sets of code requirements.

 

[ActionDave]

They must be protected at the point of supply. Interpret that how you will, but it's more specific than 'adequately.'
They are protected at their point of supply.

The 30A breaker does that. Every thing downstream is protected. The code is satisfied.

240.21 Location in Circuit
Overcurrent protection shall be provided in each ungrounded
circuit conductor and shall be located at the point where the
conductors receive their supply except as specified in
240.21(A) through (H). Conductors supplied under the pro-
visions of 240.21(A) through (H) shall not supply another
conductor except through an overcurrent protective device
meeting the requirements of 240.4

The exceptions all deal with tap conductors; those are allowed to have their correctly sized overcurrent protection farther downstream from their point of supply.

Having reviewed the definitions, I agree with you unless or until someone puts another load (or source) into the subpanel. They make enclosures that are designed for a single circuit breaker; the OP would do well to use such a one if the intent is that it serves only as a place to insert the GFCI device into the branch circuit. In that case I'd drop my objections.

So this is just a design issue for you.

Although the CMPs keep adding pounds of new requirements that fly in the face of 90.1 this is a case of the code remaining true to its purpose.

 

[electrofelon]

There are many situations with booster and lubricating pumps where they are fed from the main motor circuit protective device.
What about almost every control power transformer or surge protective device?

A conductor used as both a feeder and a branch circuit must meet both sets of code requirements.

Also wouldnt the OP have conductors that are both a feeder and a branch circuit if that 'subpanel' had a second breaker in it? Say he has a 30 amp OCPD feeding conductors supplying a panelboard which has a 50 amp and a 20 amp breaker supplying branch circuits. Wouldnt the conductors between the 30A OCPD and the panelboard be both a feeder and a branch circuit? I say the 30 amp breaker is "the final overcurrent device protecting the circuit..." making those conductors a branch circuit, but that 20 amp breaker makes it a feeder too.

 

[jim dungar]

Also wouldnt the OP have conductors that are both a feeder and a branch circuit if that 'subpanel' had a second breaker in it? Say he has a 30 amp OCPD feeding conductors supplying a panelboard which has a 50 amp and a 20 amp breaker supplying branch circuits. Wouldnt the conductors between the 30A OCPD and the panelboard be both a feeder and a branch circuit? I say the 30 amp breaker is "the final overcurrent device protecting the circuit..." making those conductors a branch circuit, but that 20 amp breaker makes it a feeder too.

I agree.

 

[GrassElectric]

Sounds like the main panel needs upgrading so you can put the proper breaker for the hot tub?


Sent from my iPad using Tapatalk

 

[Dennis Alwon]

I disagree with your opinion here.

The NEC does not distinguish a branch circuit from a feeder due to the installation of a subpanel in this case the subpanel contains a GFCI device not branch circuit OCPD.

The branch circuit OCPD is back at the main panel.

Are you saying a gfci breaker does not have ocp???