We have an old house (1927) with a detached garage. I have a full panel and sub panel we added during a recent renovation/addition, pretty sure both panels are all filled up. If I want to get a Tesla charger in the my garage, pretty sure I'm going to have to trench out from the basement corner out to the garage. Probably about 50-75 feet depending on the angle (we have a paver patio to avoid). Will we need a new sub panel in the garage? estimated cost? waiting on my electrician but curious if anyone had a similar layout...
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What all goes into getting power to a detached garage?
- Thread starter MOD220
- Start date
aerodyne
2 of 3 EV's - Defect Free!
Research TMC with search function
Time
Money
TL;DR,
Direct bury 6/2 cable, 50A GFCI breaker, Nema 6-50, plus additional Gen2 MC.
If you need more than 27mi/hr, then more money will be needed. See the TT charging guide, Tesla Tap site.
Time
Money
TL;DR,
Direct bury 6/2 cable, 50A GFCI breaker, Nema 6-50, plus additional Gen2 MC.
If you need more than 27mi/hr, then more money will be needed. See the TT charging guide, Tesla Tap site.
I've seen this issue a few times here on this forum. As mentioned, search for it, either through this site, or just throw this line into Google:
"detached garage" site:teslamotorsclub.com
There are types of cable you can direct bury, but I personally just wouldn't be very comfortable with that. So yes, I would probably do the trenching and lay conduit in there. Since you're biting the bullet to do this big amount of work with the digging and such, this is one to future proof some, so you don't ever have to try to redo it later. Run bigger conduit and thicker wire than you need for just the charging at this point. Then, for flexibility and to be able to adjust things later, have the garage end of it come up into a sub-panel. That way, you can have bus bars and breakers and such, so you can put in a 240V connection for charging and maybe a couple of small 120V circuits for a couple of outlets and an overhead light or something.
"detached garage" site:teslamotorsclub.com
There are types of cable you can direct bury, but I personally just wouldn't be very comfortable with that. So yes, I would probably do the trenching and lay conduit in there. Since you're biting the bullet to do this big amount of work with the digging and such, this is one to future proof some, so you don't ever have to try to redo it later. Run bigger conduit and thicker wire than you need for just the charging at this point. Then, for flexibility and to be able to adjust things later, have the garage end of it come up into a sub-panel. That way, you can have bus bars and breakers and such, so you can put in a 240V connection for charging and maybe a couple of small 120V circuits for a couple of outlets and an overhead light or something.
aerodyne
2 of 3 EV's - Defect Free!
Sorry if I was not clear, should have said, "Sheathed cable UL rated for direct bury"
In some locations, Sch 40 conduit is not allowed, and Romex in conduit is questionable.
Could not find Sch 80 in my Homeless Despot.
Good points on adding capability. If you have significant sunk costs with a trench (sorry) you might as well plan for future capability with subpanel and outlets as you mentioned
In some locations, Sch 40 conduit is not allowed, and Romex in conduit is questionable.
Could not find Sch 80 in my Homeless Despot.
Good points on adding capability. If you have significant sunk costs with a trench (sorry) you might as well plan for future capability with subpanel and outlets as you mentioned
First thing is that you need to determine what your needs are. Don't assume that the only solution is a 50A+ solution. For many people, a single 120V plug is more than adequate. Trenching, replacing panels and everything else may be really expensive, it's not necessarily worth it.
Look at options.
Look at options.
Also converting a 120 volt 15 amp circuit to a 240 volt 15 amp circuit may be a lot cheaper. 12 amp 240 volt EVSE is not expensive and is a good overnight charger for many commuters.
Something to consider.
If u are going to dig as Rocky mentioned ..I would go with conduit and THWN( can get that off bulk reel at HD) ..to future proof incremental cost to go with #3 or #4 wire .. Romex not supposed to run in conduit or for wet conditions
TiggerTime
Member
I have a detached garage and when it was build we put it on it's own meter.. So the House and garage are on separate lines coming off the grid.
Vinc
Member
Exact same layout, but we got lucky and the main panel had just enough left for the new 240V line. We ran the cable overhead using piping instead of digging. It did not break the bank, permits and all.
eprosenx
Active Member
I actually would heavily consider using XHHW (or rather XHHW-2) instead of THWN (really THWN-2). It is more durable and robust for pulling in conduit outdoors.
But either way is fine as long as you meet all the specifications of the cable.
THHN vs. XHHW: What Is the Difference?
I have done this twice in two different locations. At our house in Chicago we added a sub panel with a 100-amp circuit and trenched that to the detached garage. It connects to a shutoff panel, then feeds to a Tesla wall charger that provides 70amps/240volts to our X. The total costs with electricians/permitting/inspections and the wall charger was $4200.
I also ran a similar setup at my folks’ house in Michigan that we frequently visit. In this case, we added a 60amp breaker to a new replement main panel and trenched that to the detached garage. There it connects to a sub panel and branches to a garage-outlet 15-amp/120volt circuit and a 50-amp/240volt NEMA 14-50 outlet. We are using the Tesla mobile charger cable (with interchangeable plugs) to charge. Note that the mobile charger will only draw 30amps. (Tesla also sells a dedicated 50-amp mobile charger that will draw the full 50-amps) This cost us $3,200.
Good luck with your project!
Can run in conduit, but is not allowed in wet conditions.
I had thought of that, but didn't mention it in my previous comment. A lot of older buildings use those masts coming out of the roof to run electric supply lines to other buildings, but that is out of favor and it seems like very few jurisdictions would still allow that to be added to anything now.
That's 32 amps and 40 amps.
aerodyne
2 of 3 EV's - Defect Free!
That's 32 amps and 40 amps.[/QUOTE]
30 amps max is what it says on the MC Gen 2 adapter. Tesla says the regulators made them label it that way. Tesla says it is OK to run at 32A.
I did run full 32, on my recently purchased Gen 2. I found the cable got much warmer than the thicker cable of Gen 1 MC at 40A.
My thought is with only a one year warranty on the Gen 2 MC, run it derated at 27A. That is 20 mi/hr, good enough for me
30 amps max is what it says on the MC Gen 2 adapter. Tesla says the regulators made them label it that way. Tesla says it is OK to run at 32A.
I did run full 32, on my recently purchased Gen 2. I found the cable got much warmer than the thicker cable of Gen 1 MC at 40A.
My thought is with only a one year warranty on the Gen 2 MC, run it derated at 27A. That is 20 mi/hr, good enough for me
Yes, I know, and that was covered in another thread that the 30A marking was some eyerolling compliance with a document kind of thing that even Tesla doesn't expect you pay attention to and isn't really applicable to use.
That being said, however, with it being a 32A max device, I would still turn mine down a few amps, as you said you have done. I still have the old 40A 1st generation UMC, and I always keep the amp setting at about 32 instead of 40, because it keeps it very cool and doesn't heat it up much. Temperature cycling does wear on electronics connections, so it should extend the life of it some in the long term by not going so far in the daily cycles of hot and cold.
aerodyne
2 of 3 EV's - Defect Free!
I do not believe that running the Gen 2 at 32A is a safety problem, but since it only has a 1 year warranty, and there have been recent supply issues, makes sense to me not to run it at full capacity unless needed.
I keep the Gen 1 with a full complement of adapters in the car for road trips.
It has the balance of the 4 year warranty.
I also want to preserve my single on board charger which maxes out at 4O A.
My home set up to the MC connector is capable and rated for running at 50A continuous.
I keep the Gen 1 with a full complement of adapters in the car for road trips.
It has the balance of the 4 year warranty.
I also want to preserve my single on board charger which maxes out at 4O A.
My home set up to the MC connector is capable and rated for running at 50A continuous.
I strongly doubt that. 50A continuous times the 125% overrating requirement would need a 62.5 amp circuit, which you would need to round up to 65, and there's not an outlet type bigger than 60, much less one that the UMC has a plug for.
And why not? Don't come back with limited regen, because that's not a real issue. Don't respond with the battery is cold, because if it is in a garage, that's not really a big thing. and I don't think that we've heard the average daily trip.
Realistically the electrician is going to pick the cable based on local practices and code. At my house that included conduit, but you should know that new wire can't usually be pulled through old underground conduit. So if you think you will someday need more power for 2 EVs you will either need to put in heavier wire today or redig in the future.
50A shared between two EVs would be enough for most families.
Electricians will almost always recommend a new sub panel in a detached garage when adding a charger. I'm not sure if the subpanel is a good idea, or just a way to raise the price.
aerodyne
2 of 3 EV's - Defect Free!
I was not clear. Only running 40A..could not run more if I tried, car limited to 40.
Everything except the breaker and MC can handle 50A continious, should I decide to pull more, would upgrade to 60A breaker and I guess a WC.
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