Shed Sub Panel

[racer12306]

I am trying to figure out the most cost effective way to set up the sub panel in my shed. The chief inspector told me I needed a main (don't know if it was for the switching ability or the circuit protection, haven't looked it up in the code yet).

I will have a 40A 2 pole in the house, #8 THWN through PVC to the sub panel. I should only need 4 breaker slots: 1 15A for overhead lights, 2 20A for outlets and 1 20A for a dedicated air compressor.

I'd like a little room for upgrade, but not a ton because it's just a shed and I don't plan on living here forever, ie if I need to add a circuit for something I don't want to have to buy a new panel just to do it.

Any tips?

 

[mrb]

get a 8/16 (8 space -16 cir with tandems) MLO homeline panel, use a backfed 40A DP breaker for the main (dont forget the holddown kit). Make sure panel has seperate neutral and ground busses. Dont install the green bonding screw. Run 3x #8 + 1x #10 ground from the house to the panel. You need two 8ft ground rods 6 feet apart at the shed, these get connected to the ground bar in the panel as does the #10 ground from the house. When you buy the wire, buy white wire for the neutral -cant reidentify #8.

 

[racer12306]

I was planning on running 4x #8. I doubt there is much of a cost difference between the #8 and #10. The #8 is $0.31/foot. one red, one black, one white and one green.

One thing I have been wondering is what size to run to the ground rods, #10?

I'm guessing this is the panel you are talking about: http://www.homedepot.com/h_d1/N-5yc1vZ1xhc/R-100121449/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Can you provide a link to a holddown kit so I will know what I'm looking at when I go to buy it?

I'm having a hard time wrapping my head about how the backfed breaker works since it would only energize one of the two bars and it would be 240V at that. Can anyone explain that for me?

 

[sberry]

If you have a panel with more than 6 spaces you need a main, number 8 to the ground rods.

 

[sberry]

This is just personal, if I was going to the trouble of doing this it would have 6 wire, not that it is needed most of the time but in the event that one ever wants to run a welder that requires 50A service it is there.

 

[racer12306]

I don't know if I would ever have room, physically, for a welder. Plus anything I need welded I can run up to my Dad's and do there.

This is mainly for a small workshop and storage.

 

[mrb]

If you have a panel with more than 6 spaces you need a main, number 8 to the ground rods.

its not 6 spaces, its six handles. You could put in a 40 space panel with only 6 handles and be fine. If using the six handle rule the panel has to be marked as suitable for use as service equipment, and under 2005 cannot be a lighting and appliance panelboard (cant serve outlets and lights) but this seems to be gone in 2008.

 

[mrb]

I was planning on running 4x #8. I doubt there is much of a cost difference between the #8 and #10. The #8 is $0.31/foot. one red, one black, one white and one green.

One thing I have been wondering is what size to run to the ground rods, #10?

I'm guessing this is the panel you are talking about: http://www.homedepot.com/h_d1/N-5yc1vZ1xhc/R-100121449/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Can you provide a link to a holddown kit so I will know what I'm looking at when I go to buy it?

I'm having a hard time wrapping my head about how the backfed breaker works since it would only energize one of the two bars and it would be 240V at that. Can anyone explain that for me?

you have to use a 2 pole breaker for the backfed main. Instead of connecting your feeder wires to the two hot busses, you connect them to the breaker. The breaker supplies the two busses.

The holddown kit for that panel is p/n HOM4RK2LA

 

[sdowney717]

HOM4RK2HA
is a back fed main circuit retaining kit for 150-225
Amp homeline lugs panels

I was wondering if it looks any different than HOM4RK2LA
the 2HA is a rectangular stamped piece that surrounds the breaker

ECK carries this. some homeline stuff is hard to find

 

[mrb]

HOM4RK2HA
is a back fed main circuit retaining kit for 150-225
Amp homeline lugs panels

I was wondering if it looks any different than HOM4RK2LA
the 2HA is a rectangular stamped piece that surrounds the breaker

ECK carries this. some homeline stuff is hard to find

they are different. One is for each panel size.

 

[Aceman]

Price out a 100 amp main breaker panel first before you buy the main lug and backfed breaker. For how cheap I've been getting MB panels lately, I'm done backfeeding 2 pole breakers in main lug panels.

 

[racer12306]

Bumping this back up because I have aquired a free Square D QO8-16L100DS.

I have tried to find a hold down to back feed a breaker and haven't had any luck. Any advice for this one? Maybe I'm just looking in the wrong places.

 

[Charles (in GA)]

get a 8/16 (8 space -16 cir with tandems) MLO homeline panel, use a backfed 40A DP breaker for the main (dont forget the holddown kit).

Recall discussion a couple of weeks ago, the panel disconnect/main has to be rated at least 60 amps for three or more circuits. (NEC 225.39); 15 amp min for one circuit, 30 amp min for two circuits, 100 amp min for a one family dwelling, and for ALL OTHER situations, 60 amp minimum.

The panel can be supplied by less amperage, the breaker in the main panel can be 40 amp with #8 wire, but the DISCONNECT at the shed must be rated to at least 60 amps.

Charles

 

[Charles (in GA)]

Bumping this back up because I have aquired a free Square D QO8-16L100DS.

I have tried to find a hold down to back feed a breaker and haven't had any luck. Any advice for this one? Maybe I'm just looking in the wrong places.

It appears that a PK5RK is the number for a hold down bracket for Square D type QO double pole breakers used as a main

http://ecatalog.squared.com/pubs/Ci...kers/QO-QOB Circuit Breakers/48840-225-01.pdf

Charles

 

[kmacht]

Home depot has a homeline main breaker panel for about $47 that includes the panel, a 100amp main breaker, and 5 20 amp breakers. You won't find much cheaper than that. This is what I ran. As far as wire, look into 2-2-2-4 aluminum service cable. It too can be found at home depot and is $1.50 a foot. That may seem expensive but you get all 4 conductors in one cable. For the THHN 8 gage you are talking about at 31 cents a foot times 4 that already comes to $1.24 a foot. For 25 cents more a foot you can have up to 90 amp service. Even if you only want 40 right now, it is cheaper to put in the bigger wire now than to change it out later. The only thing the main breaker kit doesn't include is a seperate grounding bar. They have these at home depot in the same isle for about $3.

Keith

 

[racer12306]

It appears that a PK5RK is the number for a hold down bracket for Square D type QO double pole breakers used as a main

http://ecatalog.squared.com/pubs/Ci...kers/QO-QOB Circuit Breakers/48840-225-01.pdf

Charles

Thanks for the info. I noticed that it says those are for 150-200A panels. This is only a 100A panel. Is that still the right way to go?

Home depot has a homeline main breaker panel for about $47 that includes the panel, a 100amp main breaker, and 5 20 amp breakers. You won't find much cheaper than that. This is what I ran. As far as wire, look into 2-2-2-4 aluminum service cable. It too can be found at home depot and is $1.50 a foot. That may seem expensive but you get all 4 conductors in one cable. For the THHN 8 gage you are talking about at 31 cents a foot times 4 that already comes to $1.24 a foot. For 25 cents more a foot you can have up to 90 amp service. Even if you only want 40 right now, it is cheaper to put in the bigger wire now than to change it out later. The only thing the main breaker kit doesn't include is a seperate grounding bar. They have these at home depot in the same isle for about $3.

Keith

I'm really not going to go above 40A. I only have 100A in the house and it's just a shed. So if I wanted more power in the shed I wouldn't be comfortable keeping the 100A in the house so I would need to up that. It's just a 12x16 shed so I don't have the space to put anything big. My dad is less than 30 min away and has everything I would ever think of needed, so until I have a bigger lot I'll go there.

 

[Norcal]

If you have a panel with more than 6 spaces you need a main, number 8 to the ground rods.

# 6 & 8 AWG needs additional protection such as conduit or armor.

 

[mrb]

its not 6 spaces, its 6 handles. You could have 6 2 pole breakers.....or an 84 space panel with 6 breakers....or......

 

[Charles (in GA)]

Thanks for the info. I noticed that it says those are for 150-200A panels. This is only a 100A panel. Is that still the right way to go?

Sorry, I didn't do enough searching.

Go HERE and look at the very first box of five items listed "retaining kits".

For the most POSITIVE way to get the part number is to look at the piece of paper glued to the inside of the panel door. It will have the part number of all approved accessories for a particular panel.

Here is an example of my Siemens panel. Most brands are similar in the info they give you.

Look in the accessories, there is a "main breaker retainer" MBR1.......

You Square D should have something similar.

Charles

 

[racer12306]

Thanks a bunch for the help.

I should be able to finish up with all the electrical inside of the shed this weekend. Then I'll work on getting a trencher to bury the feeders.