How many amps do I need for detached garage?

[frankd]

pretty soon gasoline cars will be outlawed and you'll be forced to drive EVs. then you'll want the 90A service in your garage.

Is 90a what's required to charge EV's? Seems like alot.

 

[slow]

Is 90a what's required to charge EV's? Seems like alot.

many home level 2 chargers are are put on 60 amp circuits and run 48 amps continuous

 

[jeepxj]

Is 90a what's required to charge EV's? Seems like alot.

generally the "normal" size so far for home charging is 7.7kw.
32A at 240v roughly. but you panel wise you can only steady pull 80% of the rated breaker. so breaker wise you need 40a. per car. so thats 80a right there for your normal 2 car house.

now this is an option i really like for 2 car households. 16a dual charging, 32 when just one is pulling. one 50a outlet. good to go.
https://store.clippercreek.com/level2/level2-20-to-32/dual-ev-charging-station-nema-6-50-plug


16a charging at 240v is 3.8kw. that will fill up the vast majority of EV's over night from nearly dead to nearly full. we're talking hundreds of miles in a night.

 

[frankd]

. This is a storage building near our summer/hunting cabin. its normally vacant.

Well, that bit of info was never shared. When you mentioned storage building/ garage, being GJ, I think most assumed this was at your residence or home.

Yeah... I probably should've started with that. Lol. Sorry.

 

[Denwood]

30 is lots for your application. 60 if you’re planning to charge an EV when present.

 

[quickfarms]

Personally I would run #8 and use a 50 amp breaker, just bought a 500 foot spool of black for $218. Next is a spool of White.

I used #8 to run two welder circuits decades ago and put 30 amp breakers on them, due to the plug, and now the upgrade is a new breaker and plug.

Now you are going to love this. I was at a shop looking through there clearance area and picked up a partial spools of #10 green and black for $30 plus tax

 

[crazybrit]

and you need two ground rods at the shop

Is this true? I thought NEC only required two if resistance test failed.

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[crazybrit]

Yeah... I probably should've started with that. Lol. Sorry.

Yes always good to share such infgo from start. This, said, when I'm doing something I like to think of next owner and possible resale improvements.

If future owner might be using space for more tasks its frustrating to have to redo because previous owner went cheap.

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[mcbane]

Personally I would run #8 and use a 50 amp breaker, just bought a 500 foot spool of black for $218. Next is a spool of White.

I used #8 to run two welder circuits decades ago and put 30 amp breakers on them, due to the plug, and now the upgrade is a new breaker and plug.

Now you are going to love this. I was at a shop looking through there clearance area and picked up a partial spools of #10 green and black for $30 plus tax

What happened to those spoils? Fell off a truck at highway speed? Incredibly it looks like wire is ok.


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[mcbane]

Is this true? I thought NEC only required two if resistance test failed.

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The resistance test cost more than a second ground rod.


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[TractorJeff]

Has anyone checked Voltage Drop verses distance in all these Wire size/Amps recommendations?

 

[jeepxj]

mobile home feeder comes in many sizes. 150' should be 1/0 at 90a right?

 

[frankd]

Personally I would run #8 and use a 50 amp breaker, just bought a 500 foot spool of black for $218. Next is a spool of White.

I used #8 to run two welder circuits decades ago and put 30 amp breakers on them, due to the plug, and now the upgrade is a new breaker and plug.

Now you are going to love this. I was at a shop looking through there clearance area and picked up a partial spools of #10 green and black for $30 plus tax

Thanks. No one seems to stock number 8 aluminum around here. 6 seems to be the smallest I could find...which is fine because it's only .30 cents per foot. So I'm leaning towards rhat

 

[crazybrit]

The resistance test cost more than a second ground rod.

True but not the same as being required.

 

[lilredex]

If you intend to install a stick welder make it at least 50 Amp. My garage came with only 30 Amp and I have been limping (and cursing) along with that for the last thirty years.

 

[jeepxj]

If you intend to install a stick welder make it at least 50 Amp. My garage came with only 30 Amp and I have been limping (and cursing) along with that for the last thirty years.

why not upgrade?

 

[Syberia]

I ran 60 amps two years ago when the only thing I was planning on powering was a welder, but now between two EVs, a mini split, compressor, wife's animal shed, etc., that's barely adequate.

 

[jeepxj]

I ran 60 amps two years ago when the only thing I was planning on powering was a welder, but now between two EVs, a mini split, compressor, wife's animal shed, etc., that's barely adequate.

I think if you searched on here the most common answer is mobile home feeder for 90a. MHF usually under half the cost to go 100a.

 

[Crazyjake8493]

I see it's already been mentioned, but here's another vote for 2-2-2-4 MHF in aluminum. Well under $2/ft and good for 90 amps. A 60 amp breaker should be easy to find (and cheaper than a 90A) and should be more than enough.

 

[Innovate1]

I see it's already been mentioned, but here's another vote for 2-2-2-4 MHF in aluminum. Well under $2/ft and good for 90 amps. A 60 amp breaker should be easy to find (and cheaper than a 90A) and should be more than enough.

wireandcableyourway.com lists 2246 MHF for $1.40 per foot. Those same conductors in xhhw are a total of $1.16 per foot. They didn't list the price for 2224 so I compared what I could. You can get lots more choices in buying the individual strands too.

 

[Syberia]

I think if you searched on here the most common answer is mobile home feeder for 90a. MHF usually under half the cost to go 100a.

Unfortunately I went with 1" PVC and #6 copper so I definitely can't replace with MHF. Looks like if I start tripping breakers I can get away with #4 copper for the same 90 amps (technically 85 but I believe a 90 amp breaker is allowed by code) since the panel itself is good for 100 amps. Of course at that point I'm probably close to maxing out my house service at 125 amps.

Of course, an easier thing to do might be to lower the charge rate on one of the cars if it becomes an issue.

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[ROBZ71LM7]

Tesla chargers pull 48A continuous and require a 60A breaker.

 

[jeepxj]

Tesla chargers pull 48A continuous and require a 60A breaker.

that is the max setting on the current generation wall connector. you can set your max rating down to 15a breaker size.

https://www.tesla.com/sites/default...ng/Gen3_WallConnector_Installation_Manual.pdf

page 5.


the portable unit only pulls 32a max. even if its on a 14-50/6-50 receptacle.

 

[jeepxj]

Unfortunately I went with 1" PVC and #6 copper so I definitely can't replace with MHF. Looks like if I start tripping breakers I can get away with #4 copper for the same 90 amps (technically 85 but I believe a 90 amp breaker is allowed by code) since the panel itself is good for 100 amps. Of course at that point I'm probably close to maxing out my house service at 125 amps.

Of course, an easier thing to do might be to lower the charge rate on one of the cars if it becomes an issue.

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ya could get fancy fancy and stick 240-480 single phase transformers on each end making your underground line a 480 circuit.

 

[aggie113]

I have a 200amp panel pulling 120amp from the pole. Doubt I'll every need it but didn't cost much more in a new build. Future plans include solar on the roof of the garage feeding the house.

 

[dcg9381]

Future plans include solar on the roof of the garage feeding the house.

The economical price point is at 90A. I don't think many people will outrun this, but just put in 3" conduit in case of future use.
I put 30A of solar on my shop also...

 

[rburke65]

If you feel a 4 or 6 will be enough, then run 4 or 6.

 

[Bradc1989]

Yes, and to add to what Alfred said, conduit is required for the entire run, above and below grade.

Make sure you run 4 conductors, and you need two ground rods at the shop

2 grounding rods in the shop or one at each panel?

 

[mike93lx]

2 grounding rods in the shop or one at each panel?

2 at the shop

 

[Bradc1989]

2 at the shop

Why’s that? I’m in the middle of wiring a shop that is sub fed and i was under the impression there was one at the sub panel and one at the main breaker panel. Just curious as to why you have 2 at the shop

 

[mike93lx]

Why’s that? I’m in the middle of wiring a shop that is sub fed and i was under the impression there was one at the sub panel and one at the main breaker panel. Just curious as to why you have 2 at the shop

Code.

One is possible if you can prove resistance. If you are asking this, you don't have the equipment to do that, so just drive in a second one

 

[Metal-Marc]

Why’s that? I’m in the middle of wiring a shop that is sub fed and i was under the impression there was one at the sub panel and one at the main breaker panel. Just curious as to why you have 2 at the shop

Lower the impedance to ground. In plain english, you will have a better ground.

Telecom shacks have even more ground rods in the ground, but that is another subject.

 

[Bradc1989]

Lower the impedance to ground. In plain english, you will have a better ground.

Telecom shacks have even more ground rods in the ground, but that is another subject.

Interesting, makes me have more questions but I’ll go to google so as to not clutter this thread anymore

 

[dcg9381]

Interesting, makes me have more questions but I’ll go to google so as to not clutter this thread anymore

It's a "separate structure":

This should help:

https://www.ecmweb.com/national-ele...-qa-grounding-and-bonding-for-remote-building

 

[HamAndEggs]

Never read the full thread, but just recently I moved my service entrance TO my garage. Now I have 200a at my garage, and could easily go to 400a

Just came here to brag

 

[Metal-Marc]

Never read the full thread, but just recently I moved my service entrance TO my garage. Now I have 200a at my garage, and could easily go to 400a



Just came here to brag

Hahaha, that's the best way to do it.

 

[3rdgendslmech]

you can use thwn. I think all #2 thhn is dual rated thwn. its a little cheaper than xhhw-2 and easier to pull. buy your wire from a local supply house it'll probably be cheaper than the box store and they'll spool up 4 spools for you.

also, to make life easier run the outside conduit up the exterior wall and LB directly into the panel. I put my LB way down low, and then had to do another LB on the inside to get the wire up to the panel. pulling through back-to-back LBs with large guage wire is a pain. xhhw-2 made it even harder. i'd use 2" conduit and 2" LBs, minimal extra cost vs 1-1/4" and will make life easier.

I had to do something like this when I ran my wires into the house. I live in a split level with the main panel in the basement. Exterior LB is a few inches off the ground ran conduit through the house to a LB that enters the bottom of the panel. Had to put an access panel right under the cover for the main breaker panel. I ran #2 dual rated THHN in 1 1/2 conduit and it pulled pretty easy for a 130 foot run

 

[andyvh1959]

I built a detached 24x28 garage, about 20' from my attached garage, Installed a 100 amp sub panel. Its connected to the 200 amp main panel with #2 THHN copper in buried 1-1/2 conduit, two ground rods at the detached garage. I have three 30 amp circuits in the detached garage, one for my MIG welder one for the air compressor, another 30 amp for an eventual boiler to run the heated floor, the rest are 20 amp and 15 amp outlets.