Detatched garage and EVSE

[g-and-h_electric]

I need some code section clarification on this. I have to give a new client a price on an EVSE in a detatched garage ( have no more info than that at this time).

It is my understanding of the 2020 code that I WILL need a sub panel capable of at least 70 amp. The garage will need the following circuits 1) 20 Amp for GFCI receptacles in each bay ( presume 2 car garage with a single 2 car wide door), 2) 15Amp lighting circuit, 3) 15 Amp door opener circuit, 4) 60 Amp ( 48 amp charger) EVSE circuit.

My interpretation of the code is that no only do I need the appropriate "single means of disconnect for all branch circuits, but that I will also have to then bring the garage to current code. Am I correct?

Any code sections that support or disprove me will be greatly appreciated.

Remember I have neither seen the job yet, nor contacted the local AHJ.


Thank you all


Howard

 

[tortuga]

The funny thing about detached garages is they are both a 'residential occupancy' while they are not 'dwelling unit'.
The outdoor feeder to a detached garage should have a ampacity of at least the calculated load per article 220.40.
You can use the minimum lighting load for a residential occupancy of 3VA per sq ft or the 125% of the connected lighting load. And 180VA per receptacle etc. Equipment like the charger EVSE would be per 220.14(K)

 

[g-and-h_electric]

TY, got it on the load calculation! As the EVSE, is a separate branch, and the lighting door op and receptacles (at an existing minimum another), I WOULD need a subpanel with either a single main breaker, or less than 6 branch breakers, correct? My understanding for a detatched garage is 1 branch circuit or feeder to it with disconnecting means for all within the structure.

Howard

 

[tortuga]

Yeah the main disconnect at the garage has to be at least 60 amps per 225.39
You can of course use a panel with a 100A main pre installed since the protection of the feeder will be at the house (70A or whatever you choose)

 

[LarryFine]

The garage will need the following circuits 1) 20 Amp for GFCI receptacles in each bay ( presume 2 car garage with a single 2 car wide door), 2) 15Amp lighting circuit, 3) 15 Amp door opener circuit, 4) 60 Amp ( 48 amp charger) EVSE circuit.

I would definitely choose a 100a feeder and panel based on this.

 

[jaggedben]

I would definitely choose a 100a feeder and panel based on this.

I would likely put #4 on a 90A breaker (75C wiring method) unless the client told me they wanted to pay for more.

 

[infinity]

Did anyone do the actual load calculation for this garage? From a practical standpoint 60 amps is probably enough for the feeder.

 

[jaggedben]

Did anyone do the actual load calculation for this garage? From a practical standpoint 60 amps is probably enough for the feeder.

The EVSE alone requires 60A because it's continuous. So anything else makes it over 60. I believe the rest is just 3VA per sqft so likely under 10A, but maybe possibly it's a greater than 800sqft garage.

 

[g-and-h_electric]

Hey guys, just wanted to thank you for all the input on this! Turns out all the client wants is a rough price, and MAYBE he is going to buy an EV!
What a "waste of time"!..... 60 ft 1" HW buried plus the #4 wont be cheap.

Anyway, again thank you to all for the help!


Howard

 

[LarryFine]

What a "waste of time"!..... 60 ft 1" HW buried plus the #4 wont be cheap.

Consider larger and aluminum.

 

[g-and-h_electric]

Larry, great idea, but I dont think aluminum is allowed in most of the Chicago suburbs (which is where this job is). Also the 50+ ft of trenching even if I had the helper from the shop do it wont be cheap. I think this guy was looking for the $2000.00 or less job.....

 

[Gene B]

You can save a little money by not oversizing the neutral...it only needs to be as large as the EGC.