Garage wiring-opinions

[timversustheworld]

In your opinion would this situation comply with the 2020 NEC

1. Existing 14-3 branch circuit to a garage
2. Garage gets torn down and rebuilt
3. 14-3 gets brought into a subpanel in the newly rebuilt garage, converting the 14-3 to a feeder
4. From the garage subpanel a 14-2/15 amp breaker is used for lighting
5. A 12-2/20 amp breaker is used for receptacles

Legal? Why or why not?

 

[Ponchik]

Your 14 AWG is protected by 15A. Yet you are installing 20A circuit for the receptacles. When the load on the receptacles gets higher than 15A your feeder will trip. You do realize that?

 

[timversustheworld]

Your 14 AWG is protected by 15A. Yet you are installing 20A circuit for the receptacles. When the load on the receptacles gets higher than 15A your feeder will trip. You do realize that?

Yes, I am aware of that. My state is telling me that the situation as described is legal-I disagree with them.

 

[LarryFine]

Welcome to the forum.

The 20a breaker will effectively be a switch, and as said above, the breaker at the supply end is the OCPD.

 

[Ponchik]

Yes, I am aware of that. My state is telling me that the situation as described is legal-I disagree with them.

Why do you disagree?

 

[ActionDave]

May not be smart but it's not illegal.

 

[timversustheworld]

Why do you disagree?

I don't feel that I can meet the requirements of 210.11 (C) (4) with a 15 amp breaker at the house and 14 gauge wiring ahead of the subpanel/20 amp breaker in the garage

 

[hbiss]

What purpose would using a 20A breaker serve? It is legal in this instance, by the way. The 14ga wire (and everything after it) is protected back at the house by the 15A breakers.

Why not just use another 15A breaker for the receptacles? It might save you from running back to the house.

-Hal

 

[timversustheworld]

What purpose would using a 20A breaker serve? It is legal in this instance, by the way. The 14ga wire (and everything after it) is protected back at the house with a 15A breaker.

Why not just use another 15A breaker for the receptacles? It might save you from running back to the house when the lights go out.

-Hal

I realize now that it appears that I am asking if it is legal to have a higher sized breaker after a smaller. The real question though is that in the situation described, am I meeting the requirements of 210.11 (C) (4)?

 

[wwhitney]

am I meeting the requirements of 210.11 (C) (4)?

It meets the letter if not the spirit of 210.11(C)(4). 210.18 defines the rating of a branch circuit in terms of the branch circuit OCPD, not the smallest upstream OCPD. So you can apparently have a 20A branch circuit on a 15A feeder.

Now if 220 requires or required that you assign a total load to the garage of more than 1800VA, then that would be a violation. So an obvious way to avoid this loophole would be amend 220 (if it hasn't been already, I didn't check).

Cheers, Wayne

 

[timversustheworld]

So by this reasoning I could then also run a 15 amp feeder to a subpanel within a dwelling and then feed my required 20 amp bathroom receptacle circuit from this? Or my small appliance branch circuits?

 

[LarryFine]

So by this reasoning I could then also run a 15 amp feeder to a subpanel within a dwelling and then feed my required 20 amp bathroom receptacle circuit from this? Or my small appliance branch circuits?

In that regard, my opinion is no. A 20a circuit is to be expected to be able to supply 20 amps.

In other words, you're right; 210.11(C)(4) would require a feeder capable of at least 20 amps.

 

[kwired]

It meets the letter if not the spirit of 210.11(C)(4). 210.18 defines the rating of a branch circuit in terms of the branch circuit OCPD, not the smallest upstream OCPD. So you can apparently have a 20A branch circuit on a 15A feeder.

Now if 220 requires or required that you assign a total load to the garage of more than 1800VA, then that would be a violation. So an obvious way to avoid this loophole would be amend 220 (if it hasn't been already, I didn't check).

Cheers, Wayne

with the multiwire supply conductor you do have up to 3600 VA available but you only have 1800 available for an individual 120 volt load.

A potential solution if OP doesn't want to run new supply is to install a 240 x 120/240 transformer and then this is ok presuming total load calculation is not over 3600 VA.

 

[winnie]

I agree with post #10.

IMHO you have a violation of the spirit of the code, but not the letter of the code. It is clear that the code requires a branch circuit with a 20A rating. Code also defines the rating of the branch circuit as being from the final overcurrent device. So IMHO you pass the letter of the code.

But clearly you can never use the full capability of that 20A branch circuit, and code mandates a 20A circuit in that location.

Analogous situation: you install a 20A circuit to a garage, using a 20A breaker and 12ga UF cable. The garage is 1800 feet away from the panel. Compliant or not??

-Jon

 

[kwired]

I agree with post #10.

IMHO you have a violation of the spirit of the code, but not the letter of the code. It is clear that the code requires a branch circuit with a 20A rating. Code also defines the rating of the branch circuit as being from the final overcurrent device. So IMHO you pass the letter of the code.

But clearly you can never use the full capability of that 20A branch circuit, and code mandates a 20A circuit in that location.

Analogous situation: you install a 20A circuit to a garage, using a 20A breaker and 12ga UF cable. The garage is 1800 feet away from the panel. Compliant or not??

-Jon

NEC compliant - yes. Voltage drop is only a suggestion here.

I have ran into ~1800 foot feeder before, to a maintenance shed on a golf course. It was #2 aluminum triplex with 4 AWG neutral. They were telling me the issues and I first though open neutral. But eventually determined nothing wrong with it other than just simply too small for that distance to put much load at all on it without seeing large voltage variances depending on how balanced the load is.

That been many years ago now. Today I might at least suggest step up/step down to try to make that a little better. Back then they just decided to deal with it instead of upsizing the feeder.

 

[wwhitney]

So by this reasoning I could then also run a 15 amp feeder to a subpanel within a dwelling and then feed my required 20 amp bathroom receptacle circuit from this? Or my small appliance branch circuits?

Article 220 gives you a 1500VA requirement for each of those circuits. So again, compliant to the letter if your 15 amp supplied subpanel supplies at most one of those circuits per leg. But you couldn't supply all 3 from one such subpanel. And obviously contrary to the spirit or intention of the code.

Cheers, Wayne

 

[jap]

The new sub panel is nothing more than a glorified wirenut at this point.

JAP>

 

[sgtsparky]

What purpose would using a 20A breaker serve? It is legal in this instance, by the way. The 14ga wire (and everything after it) is protected back at the house by the 15A breakers.

Why not just use another 15A breaker for the receptacles? It might save you from running back to the house.

-Hal

As long as the maximum load is below 15 amps I believe it would be legal, what is the lighting load and how many receptacles, complete a load calculation to see. I can see an inspector saying it is not as a single 1800w load would be larger than the feeder was sized for.

 

[sgtsparky]

So by this reasoning I could then also run a 15 amp feeder to a subpanel within a dwelling and then feed my required 20 amp bathroom receptacle circuit from this? Or my small appliance branch circuits?

No there is a requirement for a 20 amp circuit for the kitchen x2, bathroom(s) and laundry , you can run smaller circuits as long as the required load calculations are met,

 

[kwired]

No there is a requirement for a 20 amp circuit for the kitchen x2, bathroom(s) and laundry , you can run smaller circuits as long as the required load calculations are met,

And more recent editions of NEC require at least one 20 amp circuit to the garage, with some variances depending on which year of what that circuit can or can not supply.