Detached Garage Circuit Planning

[JediDVC]

Hi, first time post and short term member. Thanks in advance for any and all suggestions.

I am starting a detached garage project in north Texas (east of Dallas). My town has adopted NEC 2020. I plan on doing all of the work except concrete and masonry and have secured a permit - not flying under the radar. I have dealt with the inspector before and he is a retired electrical inspector from the City of Dallas but seems a reasonable guy to deal with based on my pool project last year. I have finished basements and bathrooms previously but nothing in this type of work. Once I get service to the garage, I am very confident on finishing the rest. My questions center on the electrical service.

The garage will be 25’x40’ with 9’ ceilings about 10’ from my home. Last year, I had a licensed electrician run a circuit to a sub panel on the exterior rear of my home for an in ground pool and eventually to support this project.

Origin - In my attached garage, I have 2 - 200 amp Eaton CH panels. One of them was used for this pool circuit and sub panel. My electrician installed a double throw 60 amp breaker.

Run - The rise, run, and drop (up inside the garage drywall, across attic, down outside on the surface of brick in conduit) to the sub panel is 85 feet. He used Encore Type SE, Style R 2-2-2-4 Aluminum wire.

End - Eaton BR48 Type 3 Rainproof cabinet with sub panel which has four slots. The pool uses a double throw 20 amp 230v for a variable speed pump and a third slot of 20 amp for the LED lights and service/convenience outlet at the pool equipment location. That run is about 60 feet.

The proposed run from the exterior sub panel to the panel in the garage will be 30 feet at most, including rise/fall. I intend to put the entire garage run in conduit prior to pouring the foundation/slab.

The pool electrician that completed the run from the sub panel to the pool equipment said that my first electrician did not give me a big enough panel to also do the garage. I know there is supposed to be at least a single 20 amp circuit to a detached garage. My proposed demand in the garage will be run of the mill for the most part. LED lights overhead in all likelihood, wall outlets, garage door opener outlet (one 16x7 door). I will sub-frame it for a 13x13 office area with a mini split. 9k BTU seems to be the smallest available and most appear to be 120v, but will plan on a 220v circuit in case. No welder, compressor or other heavy use items will be used, just hand held tools. Also no full size refrigerator (may have a mini in the office) or freezer planned. I am all about building in expansion and not trying to be cheap or skimp, but realistic based on the future use and demand.

Here are the questions:

1. Do I need to upgrade the 60A breaker in the attached grade panel? Probably a good idea regardless. However, based on the run, size of wire, and potential load, what size upgrade is appropriate? I tried to use the manufacturer spec sheet to determine the max amp load for the wire, but it is not making sense to me with the temperature matrix.

2. Is that exterior sub panel too small and will need to be upgraded before running the garage circuit?

3. What size breaker at the sub panel for the garage?

4. What size and type of wire from the exterior sub panel in the conduit to the garage panel?

5. While I am here begging for advice, will I need GFCI breakers only in the garage, or do I need AFCI capable breakers as well?

I know I need 2 grounding rods for the garage. Open to any other missed items on my part.

Sorry for being so wordy, but I see more questions and fights on thread replies due to a lack of information by the original posters. If I have missed anything needed, please let me know. Thanks again.

 

[cmandp]

I cannot answer most of your questions but I believe the Aluminum 2-2-2-4 SER run from your main panel to your outside sub-panel can only handle 75A Edit: (Yeah I followed the line on the table wrong its 90A like everyone said). And your 4 slot sub-panel has no more space for a double pole breaker to feed the garage. The feed to the sub-panel would need to be increased anyway I think to have a decent size supply to the new garage.

You should do a load calculation on the new garage so you know how to size the feed.

Those more experienced than me can advise better on what to do. But to me I'd just run a new feed on a new breaker directly to the new garage from your main panel.

 

[ddawg16]

Welcome to GJ from a fellow Native Texan (mid cities area)...but now living in California

Just so I have this right....
Your 60A double throw...is actually a 60A/220 feed.
Your pool is the 220 Vac motor and 120 Vac for lights.

That potentially leaves 30+ Amps/220 for the garage.

Your 60A/220 is actually good for 120A/120V (almost)

I doubt your pool motor actually pulls more than 10A. Those lights? 2-3 Amps. So, you have plenty of power for the garage.

Your bigger issue is the sub-panel outside. You need more spaces.

I would get a different panel with more spaces.

If it was me....
6 Space sub
2 Double breakers, 1 for pool motor (20A) and a 40A for the garage.
1 20A for pool lights.

In the garage, another 6 space panel.
1 20A double breaker (for your 220)
4 20A single breakers.

Don't worry if things sound like they add up to be too much. My main panel is 200A...but if you add up the amps on all the handles, it's over 600 Amps.....

I have 50 A/220 going to my garage. I have never tripped any of the breakers.

Detached garage....no AFCI...but everything has to be GFCI now. You might consider using GFCI breakers just to make life easier.

 

[pattenp]

I cannot answer most of your questions but I believe the Aluminum 2-2-2-4 SER run from your main panel to your outside sub-panel can only handle 75A. And your 4 slot sub-panel has no more space for a double pole breaker to feed the garage. The feed to the sub-panel would need to be increased anyway I think to have a decent size supply to the new garage.

You should do a load calculation on the new garage so you know how to size the feed.

Those more experienced than me can advise better on what to do. But to me I'd just run a new feed on a new breaker directly to the new garage from your main panel.

If the feeder is underground you can't use SER even if in conduit. Also #2 aluminum is 90A.

 

[JediDVC]

I cannot answer most of your questions but I believe the Aluminum 2-2-2-4 SER run from your main panel to your outside sub-panel can only handle 75A. And your 4 slot sub-panel has no more space for a double pole breaker to feed the garage. The feed to the sub-panel would need to be increased anyway I think to have a decent size supply to the new garage.

You should do a load calculation on the new garage so you know how to size the feed.

Those more experienced than me can advise better on what to do. But to me I'd just run a new feed on a new breaker directly to the new garage from your main panel.

I saw the 75A as well and agree. Thanks.

 

[JediDVC]

Welcome to GJ from a fellow Native Texan (mid cities area)...but now living in California

Just so I have this right....
Your 60A double throw...is actually a 60A/220 feed.
Your pool is the 220 Vac motor and 120 Vac for lights.

That potentially leaves 30+ Amps/220 for the garage.

Your 60A/220 is actually good for 120A/120V (almost)

I doubt your pool motor actually pulls more than 10A. Those lights? 2-3 Amps. So, you have plenty of power for the garage.

Your bigger issue is the sub-panel outside. You need more spaces.

I would get a different panel with more spaces.

If it was me....
6 Space sub
2 Double breakers, 1 for pool motor (20A) and a 40A for the garage.
1 20A for pool lights.

In the garage, another 6 space panel.
1 20A double breaker (for your 220)
4 20A single breakers.

Don't worry if things sound like they add up to be too much. My main panel is 200A...but if you add up the amps on all the handles, it's over 600 Amps.....

I have 50 A/220 going to my garage. I have never tripped any of the breakers.

Detached garage....no AFCI...but everything has to be GFCI now. You might consider using GFCI breakers just to make life easier.

Thanks for the welcome dawg. I appreciate it and your response. I totally spaced off that it is 220V 60 A. That makes total sense. I had a feeling that I would need to change the cabinet outside of a separate circuit as cmandp suggested. Good call on the GFCI breakers in the garage cabinet, that was my intention. I checked and my pool pump (Pentair VSF) has a max draw of 16A, which I never hit as you said, even in prime mode when it starts up. I guess one other observation is that Eaton’s next size breaker is 70A, but probably not worth fooling with.

 

[bamawildcat]

Agree with above, the outdoor sub-panel installed doesn't have room for another two pole breaker. Easy solution may be to buy his 6 space brother, and transfer the guts and front panel (and thus listing sticker) to the existing can on the wall: https://www.homedepot.com/p/Eaton-B...g-Loadcenter-with-Cover-BR612L125RP/100164090

Also, your electrician put Square D Homeline breakers in your Cutler Hammer/Eaton box. If those aren't on the sticker inside, you may want to swap then for Eaton breakers before your next inspection.

 

[JediDVC]

If the feeder is underground you can't use SER even if in conduit. Also #2 aluminum is 90A.

Thanks. Understood on the wire use underground. I was probably switching to copper from the exterior sub panel to the garage panel. I am not sure the 90A is correct. It states 75A at 60 degrees Celsius (140F) and 90A at 75 degrees Celsius (167F). I am assuming they are talking ambient temperatures? That was part of my questioning of the chart.

 

[JediDVC]

Agree with above, the outdoor sub-panel installed doesn't have room for another two pole breaker. Easy solution may be to buy his 6 space brother, and transfer the guts and front panel (and thus listing sticker) to the existing can on the wall: https://www.homedepot.com/p/Eaton-B...g-Loadcenter-with-Cover-BR612L125RP/100164090

Also, your electrician put Square D Homeline breakers in your Cutler Hammer/Eaton box. If those aren't on the sticker inside, you may want to swap then for Eaton breakers before your next inspection.

Thanks Bama. Good points.

 

[pima67]

Another point to consider is that the pool pump (for cleaner I assume ) can be scheduled to run very early in the morning. Usually it doesn't need to run all day. Or at least you can schedule to run the pump during times you would not be in the garage using other equipment.

 

[JediDVC]

Another point to consider is that the pool pump (for cleaner I assume ) can be scheduled to run very early in the morning. Usually it doesn't need to run all day. Or at least you can schedule to run the pump during times you would not be in the garage using other equipment.

Yes. It runs daily from 8-5 and absolutely can be changed. Good point. Thank you.

 

[JediDVC]

I ordered the BR 125 amp 6 space 12 circuit box that Bama suggested. I am going to go that route and retro it up. Thanks. Anybody have suggestions for the wire run from the exterior sub panel to the garage panel?

 

[pattenp]

Thanks. Understood on the wire use underground. I was probably switching to copper from the exterior sub panel to the garage panel. I am not sure the 90A is correct. It states 75A at 60 degrees Celsius (140F) and 90A at 75 degrees Celsius (167F). I am assuming they are talking ambient temperatures? That was part of my questioning of the chart.

Up until 2017 NEC #2 Al SER was limited to 60degC if run within insulation or 75degC if not run within insultion. That changed with 2017 NEC so it's now just 75degC for 90A.

 

[pattenp]

I ordered the BR 125 amp 6 space 12 circuit box that Bama suggested. I am going to go that route and retro it up. Thanks. Anybody have suggestions for the wire run from th e exterior sub panel to the garage panel?

I assume in conduit underground. If so, use individual conductors of Al XHHW-2. This is 75degC wire, so #1 is 100A and #2 is 90A. The ground can be #6 Al for up to 100A.

 

[ddawg16]

Make sure you

I ordered the BR 125 amp 6 space 12 circuit box that Bama suggested. I am going to go that route and retro it up. Thanks. Anybody have suggestions for the wire run from the exterior sub panel to the garage panel?

install a double pole breaker rated for the same Amps as the feeder breaker and then run the power to the box through it.
When you have more than 6 breakers in a sub, it has to have a main disconnect.

Someone at the NEC concluded if the **** hit the fan, a guy can't turn off more than 6 breakers quickly.

 

[JediDVC]

I assume in conduit underground. If so, use individual conductors of Al XHHW-2. This is 75degC wire, so #1 is 100A and #2 is 90A. The ground can be #6 Al for up to 100A.

That is correct - PVC underground from the exterior sub panel on the house to the garage panel coming up in the slab through the base/sill plate.

 

[ddawg16]

That is correct - PVC underground from the exterior sub panel on the house to the garage panel coming up in the slab through the base/sill plate.

While you are at it....do an Ufer ground. Especially since you are pouring a slab.

Ufer ground is better than ground rods

 

[Norcal]

Your house has CH panels which are top of the line, mixing them with the worst panel on the market Eaton BR (I call them Zinsco II), is not a great idea namely because they are not interchangeable with each other & the BR line caters to bottom end of the market like Zinsco catered to in their time.

 

[JediDVC]

Your house has CH panels which are top of the line, mixing them with the worst panel on the market Eaton BR (I call them Zinsco II), is not a great idea namely because they are not interchangeable with each other & the BR line caters to bottom end of the market like Zinsco catered to in their time.

Thanks for the observation. I had no idea on their reputation. I’m not impressed with their website to get spec info, etc. I’m also a little miffed at the electrician right now for a couple of items, some of them here, but also now recalling the lead-up to hiring him. He had good reference/reviews. I feel now he did the job just well enough, perhaps thinking he may not get the additional work for the garage, but who knows. I never told him that I was thinking of doing it myself. But if he did get called back, why screw yourself if you do get the follow-on work? SMH

 

[ddawg16]

Thanks for the observation. I had no idea on their reputation. I’m not impressed with their website to get spec info, etc. I’m also a little miffed at the electrician right now for a couple of items, some of them here, but also now recalling the lead-up to hiring him. He had good reference/reviews. I feel now he did the job just well enough, perhaps thinking he may not get the additional work for the garage, but who knows. I never told him that I was thinking of doing it myself. But if he did get called back, why screw yourself if you do get the follow-on work? SMH

Electricians are kinda like Car paint shops.

Maco will do a decent job......but if you want a really good job....ya gotta pay

 

[u2slow]

Just for a different perspective... I skipped the electrical entirely so as to direct all funding toward bringing the building to lockup. After that, I could dabble with utilities as time/funds allowed.

 

[JediDVC]

Thanks to everyone for the feedback. It was very helpful!

 

[JediDVC]

Agree with above, the outdoor sub-panel installed doesn't have room for another two pole breaker. Easy solution may be to buy his 6 space brother, and transfer the guts and front panel (and thus listing sticker) to the existing can on the wall: https://www.homedepot.com/p/Eaton-B...g-Loadcenter-with-Cover-BR612L125RP/100164090

Also, your electrician put Square D Homeline breakers in your Cutler Hammer/Eaton box. If those aren't on the sticker inside, you may want to swap then for Eaton breakers before your next inspection.

Thanks for the feedback. I went that route and finished the breaker box swap out - with the correct breakers. It looks good and appreciate the suggestion for the time savings.

 

[bad_idea]

Looks like you have gotten sound advice. I have a nugget on the conduit from the house to the shop. NEC requires any PVC conduit exposed to possible damage must be schedule 80. That means the chunk of conduit coming out of the ground at each end needs to be schedule 80. To simplify things I ran schedule 80 the whole way for my run. I also heat bent the conduit with a heat gun as no one had schedule 80 90s or 45s in town, was fairly simple. I also bought my conduit at the local electrical supply house as the box stores do not carry schedule 80. I used 1 1/2" to have plenty of room to pull the 2-2-2-4 MHF I used through. Also, cable lube makes all the difference in the world pulling the cable in.

 

[JediDVC]

Looks like you have gotten sound advice. I have a nugget on the conduit from the house to the shop. NEC requires any PVC conduit exposed to possible damage must be schedule 80. That means the chunk of conduit coming out of the ground at each end needs to be schedule 80. To simplify things I ran schedule 80 the whole way for my run. I also heat bent the conduit with a heat gun as no one had schedule 80 90s or 45s in town, was fairly simple. I also bought my conduit at the local electrical supply house as the box stores do not carry schedule 80. I used 1 1/2" to have plenty of room to pull the 2-2-2-4 MHF I used through. Also, cable lube makes all the difference in the world pulling the cable in.

Thank you. And you provided more as well. I noticed Lowe’s only had schedule 40 and figured HD would be the same. I was looking at 1 1/2” too.