Shed wiring question

[rbstern]

Getting ready to do a shed project that has the following parameters:

1) Power to shed will be from an exterior, post-mounted meter and breaker panel.

2) Distance from panel to shed anticipated to be approximately 50'.

3) Shed needs two circuits:
a) 20A dedicated to an HVAC split system (can be either 240v or 120v) and
b) 20A circuit for three outlets.

My question: Does this application require a subpanel in the shed? The NEC is a bit tricky to interpret for a specific case: It seems that if the HVAC is 240v, it is not considered a parallel feeder with the second 20A/120v line, and both circuits to the shed can be wired directly to the external breaker panel, without a need for a subpanel.

I don't have a problem doing a subpanel, if it's required by code, but the shed will be a temporary setup, and since I have a breaker panel nearby with ample capacity, so I don't want to overkill this, if I don't have to.

 

[ponytug]

For non-professionals at least, the NEC is not simple in my opinion, but I believe that you need a sub-panel. AC units alone get a waiver, but do need a disconnect nearby, but you have more than that. Therefore, I think you need the sub panel. More here, if you want;
Sub-panel, MLO or Main-Breaker requirements

I am not an NEC expert!

All the best,

Peter

 

[rbstern]

For non-professionals at least, the NEC is not simple in my opinion, but I believe that you need a sub-panel. AC units alone get a waiver, but do need a disconnect nearby, but you have more than that. Therefore, I think you need the sub panel. More here, if you want;
Sub-panel, MLO or Main-Breaker requirements

I am not an NEC expert!

All the best,

Peter

I think that discussion you linked focuses on a different issue: Whether or not the sub-panel needs a main breaker to protect the feed and circuits in the subpanel. Pretty sure, with only two circuits, I wouldn't need a main breaker in a sub-panel. The breaker in the source panel (on the post I described) provides the needed protection.

My question is whether or not the subpanel is required.

EDIT: Aware of the need for AC disconnect.

 

[JPRambo]

What is the amp draw of the mini split(?) On 120volt?
If only 50' I think I would put a 2/4 circuit panel and put 240v/30a 4 wire to it.

 

[Topzide]

If 50' from post panel, just run a 20amp and what you need for hvac from there. No different than in house with panel on opposite side. As long as proper gauge wire for loads and length and you said was temporary. If you had a sub panel laying around, use it. Not sure if a local code would need more. A lot of mobile homes are set up with panel outside on pole.

 

[rbstern]

What is the amp draw of the mini split(?) On 120volt?
If only 50' I think I would put a 2/4 circuit panel and put 240v/30a 4 wire to it.

IIRC, 17 amps on 120v, and 9 amps on 240v.

 

[JPRambo]

IIRC, 17 amps on 120v, and 9 amps on 240v.

I think you will end up with nuisances tripping of circuit breaker at that amperage. Keeping it below 16 is recommended at 80% of 20 amps.

 

[MossRoad]

I think that discussion you linked focuses on a different issue: Whether or not the sub-panel needs a main breaker to protect the feed and circuits in the subpanel. Pretty sure, with only two circuits, I wouldn't need a main breaker in a sub-panel. The breaker in the source panel (on the post I described) provides the needed protection.

My question is whether or not the subpanel is required.

EDIT: Aware of the need for AC disconnect.

I'd guess that if you have a panel at the meter on the pole, that is considered your main panel, and any panel after that would be wired as a sub-panel.

 

[LouNY]

I wouldn't bother with a sub panel.
I'd run a 12/3 with grd for 240 v for the AC and a 12/2 with grd for the 20 amp receptacles.

Now you mentioned 3 120V receptacles are they going to be heavily loaded were a single 20 Amp breaker will not be sufficient?

If so then I'd consider a sub panel feed with a 30 Amp two pole on #10 wire or go whole hog and #6 with a 50 Amp,
then add the breakers you need at that panel.

 

[MAX-24-Dean]

Getting ready to do a shed project that has the following parameters:
1) Power to shed will be from an exterior, post-mounted meter and breaker panel.
2) Distance from panel to shed anticipated to be approximately 50'.
3) Shed needs two circuits:
a) 20A dedicated to an HVAC split system (can be either 240v or 120v) and
b) 20A circuit for three outlets.
My question: Does this application require a subpanel in the shed? The NEC is a bit tricky to interpret for a specific case: It seems that if the HVAC is 240v, it is not considered a parallel feeder with the second 20A/120v line, and both circuits to the shed can be wired directly to the external breaker panel, without a need for a subpanel.

I don't have a problem doing a subpanel, if it's required by code, but the shed will be a temporary setup, and since I have a breaker panel nearby with ample capacity, so I don't want to overkill this, if I don't have to.

Yes, a sub panel will be required. NEC 225.30

 

[bigtiller]

I think putting 3 outlets on a 20 amp circuit and a second circuit for an HVAC will leave you wanting more in the near future.

If you put a 100 amp breaker box in the shed and run a heavy enough line to feed it from the pole, it will be there and ready for your future projects inside the shed.

 

[MossRoad]

I wouldn't bother with a sub panel.
I'd run a 12/3 with grd for 240 v for the AC and a 12/2 with grd for the 20 amp receptacles.

Now you mentioned 3 120V receptacles are they going to be heavily loaded were a single 20 Amp breaker will not be sufficient?

If so then I'd consider a sub panel feed with a 30 Amp two pole on #10 wire or go whole hog and #6 with a 50 Amp,
then add the breakers you need at that panel.

I'm not saying this is the case with the OP, but in some areas it's against code to run more than one circuit to an outbuilding. Two or more requires a sub panel.

 

[MossRoad]

I think putting 3 outlets on a 20 amp circuit and a second circuit for an HVAC will leave you wanting more in the near future.

If you put a 100 amp breaker box in the shed and run a heavy enough line to feed it from the pole, it will be there and ready for your future projects inside the shed.

That's similar to what I did for our garage.

I ran a 50 amp 220v circuit from the house to the garage into a disconnect. Then I put an 8 or 10 place box under the disconnect(can't remember off the top of my head). This allowed me to disconnect the garage from the house if I wanted work in the box.

 

[rbstern]

I'm not saying this is the case with the OP, but in some areas it's against code to run more than one circuit to an outbuilding. Two or more requires a sub panel.

And that's where the NEC gets confusing. There are a variety of exceptions to NEC 225.30, and I'm trying to understand if they apply.

Ultimately, I'll put a sub-panel in if I have to. Just want to make sure that's what is required.

 

[newbury]

but the shed will be a temporary setup

Define "temporary".
My son built some wooden steps outside a new house in Pa., it was supposed to have concrete when finished.
The house was not considered "finished" and FULLY taxable until the temporary steps were torn out and the concrete steps were poured and inspected by the county.
It took YEARS.

 

[MossRoad]

And that's where the NEC gets confusing. There are a variety of exceptions to NEC 225.30, and I'm trying to understand if they apply.

Ultimately, I'll put a sub-panel in if I have to. Just want to make sure that's what is required.

My thoughts are if you go with no sub panel, and I may have missed or be incorrect about some things, you're going to have to at the minimum:

- take up 3 breaker slots in the original panel.
- one single pole breaker.
- one double pole breaker.
- one cable with 2+N+G out to the shed for 110
- one cable with 3+G out to the shed for 220
- anything else that I can't think of.

If you go with a sub panel:

- take up two breaker slots in the original panel
- one double pole breaker in original panel
- one sub panel at the shed
- one single pole breaker at the shed
- one double pole breaker at the shed
- one larger cable with 3+G from original panel to shed

Pros:
- you'll take up 1 less slot at the original panel.
- no 110v cable from house to shed needed.
- room for additional circuits at the shed in the future (big plus for me)
- only 1 wire to run

Cons:
- one more breaker to purchase
- one sub panel to purchase
- may have to purchase an additional ground rod
- heavier feeder wire to shed will cost more.
- two cables have to leave the house and enter the shed
- it may be the only legal way to get 2 circuits to the garage in your area

Anyhow, just some things to think about. It's always nice to have power in an outbuilding. And it seems like I'm always wishing I had an additional outlet on mine.

Good luck with your project.

 

[MossRoad]

Got me thinking about how I wired our garage. This is a diagram of the entire setup from meter, through house, to garage. Kinda grainy, but you get the idea.

 

[ponytug]

@rbstern Why penny pinch on this one? Why wouldn't you just put in a sub panel? I would put in a sub panel and future proof your options, as @MossRoad did.

All the best,

Peter