Another "Sub panel in the Shed" thread

[slackdaddy1]

I have a 12'x10' Shed 6' from the side wall of the detached shop. The electric meter for the shop along with the shop's 200A panel (inside) are on this wall about 9' from the corner of the shed. The shop has it's own 200A service and ground rods in no way associated with the house.

I am moving my compressor to the shed (80 gallon, 5 HP (230v on 30A breaker now) and would like 1 or maybe 2 115v circuits in the shed.
A sub panel in the shed seems like the obvious choice ?? Burying PVC conduit 18" deep from the shed and an LB body into the back of the panel and pulling 15' of THNN would be easy.
(rural area, there will not be permit/inspection)

Questions
Do I have to drive separate ground rods for the shed,, or can I hook onto the garage ground rods that are 9' away from the shed??
Unbond the neutral bar in the sub panel,,

Or should I just run a 230 circuit and a 115 circuit from the shop panel and forgo a sub panel?
I DO plan on adding a wall switch in the garage and a contactor for remote on/off of the compressor,, HMM.

So with the remote on/off of the compressor in mind,, suggestions on what path I should take.

 

[wyliesdiesels]

I have a 12'x10' Shed 6' from the side wall of the detached shop. The electric meter for the shop along with the shop's 200A panel (inside) are on this wall about 9' from the corner of the shed. The shop has it's own 200A service and ground rods in no way associated with the house.

I am moving my compressor to the shed (80 gallon, 5 HP (230v on 30A breaker now) and would like 1 or maybe 2 115v circuits in the shed.
A sub panel in the shed seems like the obvious choice ?? Burying PVC conduit 18" deep from the shed and an LB body into the back of the panel and pulling 15' of THNN would be easy.
(rural area, there will not be permit/inspection)

Questions
Do I have to drive separate ground rods for the shed,, or can I hook onto the garage ground rods that are 9' away from the shed??

I see no reason why you cant do that

Unbond the neutral bar in the sub panel,

yes the feeder to this subpanel needs to be 4-wire and the neutral bus needs to be unbonded.

Or should I just run a 230 circuit and a 115 circuit from the shop panel and forgo a sub panel?
I DO plan on adding a wall switch in the garage and a contactor for remote on/off of the compressor,, HMM.

So with the remote on/off of the compressor in mind,, suggestions on what path I should take.

a subpanel is easier than running separate underground circuits.

 

[sparky 1971]

So with the remote on/off of the compressor in mind,, suggestions on what path I should take.

Use a toggle switch in the shop to make and break the control wiring off of the compressor pressure switch. Use a switch that lights up when on and put it with the rest of the shop switches to cut down on the probability of forgetting to turn the compressor off.

 

[mike93lx]

If it really will only be the compressor and two 120v circuits, I'd probably run a line for the comp into a disconnect then a MWBC into a two pole switch and two gfci's. Then add your control circuit for the compressor.

There are only so many circuits that could be needed in a 12x20, so the added flexibility of a panel seems unnecessary.

 

[75gmck25]

You don't really need to install a sub-panel in the shed if you only need two 120 volt circuits.

If you bury a 12/3 MWBC line to the shed you will have the capability for two 20 amp circuits. Check the local code for this installation (even if it is not inspected, code compliance is still the right solution), but it used to only require burying the correct Uf-B wire (initially I used the incorrect term "wet rated NM" wire) at 12" for this single 120 volt run (although you will get two 120 volt circuits). It's a simple, compliant solution for this type of requirement.

 

[PCustoms]

You don't really need to install a sub-panel in the shed if you only need two 120 volt circuits.

If you bury a 12/3 MWBC line to the shed you will have the capability for two 20 amp circuits. Check the local code for this installation (even if it is not inspected, code compliance is still the right solution), but it used to only require burying the correct wet-rated NM wire at 12" for this single 120 volt run (although you will get two 120 volt circuits). It's a simple, compliant solution for this type of requirement.

What exactly is wet rated NM?

 

[mike93lx]

What exactly is wet rated NM?

Uf-b

 

[wyliesdiesels]

the correct wet-rated NM wire at 12" for this single 120 volt run (although you will get two 120 volt circuits). It's a simple, compliant solution for this type of requirement.

No such thing as wet rated NM and 18” is required unless the circuit is fed by a GFCI

 

[wyliesdiesels]

Uf-b

Which isnt NM.

 

[mike93lx]

Which isnt NM.

Its non metallic.

I bet you could figure out what he meant.

Let's clarify and educate instead of just busting balls. Until this board is sparkies only, there will always be things like this coming up

 

[wyliesdiesels]

Its non metallic.

I bet you could figure out what he meant.

Let's clarify and educate instead of just busting balls. Until this board is sparkies only, there will always be things like this coming up

theres specific definitions in the NEC. will we stick to them or not. UF-B is not NM-b nor is NM-b UF-B. has nothing to do with ball busting

 

[mike93lx]

theres specific definitions in the NEC. will we stick to them or not. UF-B is not NM-b nor is NM-b UF-B. has nothing to do with ball busting

Geez bud. I get that using the right definitions is important but also get that many don't know them.

Saying "there is no such thing as wet rated NM" without adding anything to help on that subject is unhelpful at best.

A simple "I think you mean UF-B" is not hard

 

[slackdaddy1]

You don't really need to install a sub-panel in the shed if you only need two 120 volt circuits.

If you bury a 12/3 MWBC line to the shed you will have the capability for two 20 amp circuits. Check the local code for this installation (even if it is not inspected, code compliance is still the right solution), but it used to only require burying the correct wet-rated NM wire at 12" for this single 120 volt run (although you will get two 120 volt circuits). It's a simple, compliant solution for this type of requirement.

It would be 1) 30amp 230v and 1) 20amp 115v (possibly 2

 

[mike93lx]

It would be 1) 30amp 230v and 1) 20amp 115v (possibly 2

Are you familiar with a MWBC? You can add a second hit and share the neutral and ground wire, giving you another circuit for low cost. You need to hook it up to a two pole breaker (the style you use for a 240v circuit), then use a pair of gfci receptacles. After those receptacles, you need to keep the wiring separate.

 

[slackdaddy1]

Are you familiar with a MWBC? You can add a second hit and share the neutral and ground wire, giving you another circuit for low cost. You need to hook it up to a two pole breaker (the style you use for a 240v circuit), then use a pair of gfci receptacles. After those receptacles, you need to keep the wiring separate.

Mildly familiar,, just not with piggybacking on an active 240v, 30amp line that feeds a motor.
So I am basically doing a subpanel in the shed,, but not using a subpanel or any breakers out there?

Not sure I can fit (or it's safe) 10awg wire on a 120v GFCI outlet?

 

[mike93lx]

Mildly familiar,, just not with piggybacking on an active 240v, 30amp line that feeds a motor.
So I am basically doing a subpanel in the shed,, but not using a subpanel or any breakers out there?

Not sure I can fit (or it's safe) 10awg wire on a 120v GFCI outlet?

No, it's a second circuit and completely separate. You run a 3 or 4 wire for the comp (either are fine since you don't need a neutral) and a 4 wire for the MWBC. Comp is on a 30a breaker, MWBC is on a 20a if you run #12.

If you want to only run one circuit, you need a sub.

10 is fine for a 120v circuit (voltage isn't what matters, it's current). In this case, it would be a waste as the run is so short, but as an example, I have a MWBC to a shed that is 130' from a sub, so I ran #10 in order to have the full 20a once I account for voltage drop

 

[Bigbandguy]

Suggest framing a small roofed closet outside the shed for the compressor. The damn thing will deafen you if it is inside the workshop with you. An outside box will make the place much more comfortable to work in and just as easy to wire up. Just a thought.

 

[Raisedonadeere]

Framing a small shed could be a very good idea, I agree.

Gotta share this. In a move I wanted my compressor running before I got my detached garage built. I put the compressor in a 12x16 2x4 metal siding shed with 2x8 floor joists covered in 1' plywood flooring. Did a subpanel etc. When I turned on the compressor it made a most horrible racket and could not keep it from dancing around on the floor. It had always sounded smooth and no thought of vibration for past 30 years on concrete floors so even though I knew there could be some different dynamics with the wood floor to explain the dancing around I thought something had happened during the move and 6 months storage to damage it, like rusting the cylinders or something. Well, the compressor checked out, I bolted it down and it ran fine but boy what a racket in that shed. It now sits in my garage plumbed in and purrs like compressors do.

 

[slackdaddy1]

Suggest framing a small roofed closet outside the shed for the compressor. The damn thing will deafen you if it is inside the workshop with you. An outside box will make the place much more comfortable to work in and just as easy to wire up. Just a thought.

Currently the compressor IS in my 22x32' shop,, I am moving it to the shed 8' from the shop.

 

[yatg]

No, it's a second circuit and completely separate. You run a 3 or 4 wire for the comp (either are fine since you don't need a neutral) and a 4 wire for the MWBC. Comp is on a 30a breaker, MWBC is on a 20a if you run #12.

If you want to only run one circuit, you need a sub.

10 is fine for a 120v circuit (voltage isn't what matters, it's current). In this case, it would be a waste as the run is so short, but as an example, I have a MWBC to a shed that is 130' from a sub, so I ran #10 in order to have the full 20a once I account for voltage drop

Thought you could only have a single circuit/feeder to a structure in most cases.

 

[sparky 1971]

Thought you could only have a single circuit/feeder to a structure in most cases.

Not anymore. I don't remember if the 2017 or 2020 allowed multiple circuits to another building but it happened. I see no reason for it in this case, when a feedercould be run just as easy, but if the shed already had a 120 circuit and a 240 circuit was added, it would be allowed.

 

[finn]

Use a toggle switch in the shop to make and break the control wiring off of the compressor pressure switch. Use a switch that lights up when on and put it with the rest of the shop switches to cut down on the probability of forgetting to turn the compressor off.

You still need a disconnect within eyesight of the hard wired compressor, don’t you?

Seems easiest to put that in the shed and use the breaker in the shop as an alternative.

I personally wouldn’t be comfortable energizing a compressor without being able to lay eyes on it while doing so.

 

[sparky 1971]

.

 

[sparky 1971]

You still need a disconnect within eyesight of the hard wired compressor, don’t you?

The shed is 12X10 so if he puts a sub panel out there, which is what I was going with, a breaker in the sub can be the disconnect since within eyesight is within 50' and unobstructed from view.

Seems easiest to put that in the shed and use the breaker in the shop as an alternative.

If it's a feeder, everything in the shed will get turned off, and he will have to remember to do it every time. Not so bad to forget to turn it on, but forgetting to turn it off could result in a lot of unnecessary run cycles. And I wouldn't want to have to go in the shop every time all I wanted to do was turn the lights on in the shed just to get something.

I personally wouldn’t be comfortable energizing a compressor without being able to lay eyes on it while doing so.

If it's a switch opening and closing the control, what's the difference from that and the pressure switch closing every time the pressure get's low enough?

 

[finn]

The shed is 12X10 so if he puts a sub panel out there, which is what I was going with, a breaker in the sub can be the disconnect since within eyesight is within 50' and unobstructed from view.


If it's a feeder, everything in the shed will get turned off, and he will have to remember to do it every time. Not so bad to forget to turn it on, but forgetting to turn it off could result in a lot of unnecessary run cycles. And I wouldn't want to have to go in the shop every time all I wanted to do was turn the lights on in the shed just to get something.

If it's a switch opening and closing the control, what's the difference from that and the pressure switch closing every time the pressure get's low enough?

That’s sort of what I was getting at. I wouldn’t want to control the compressor from the shop.. Running 240 to the shed and then installing a sub panel seems the way to go. That means new separate ground rods, I believe, since it’s technically in a separate structure (in order to prevent grounding loops).

 

[Firstram]

So with the remote on/off of the compressor in mind,, suggestions on what path I should take.

I have used cheap Christmas tree remotes to trigger 50 amp relays for dust collectors. If you can get a reliable signal from inside the shop it will work great. Just use a relay with 120 vac coil to power up the compressor.