Detached Garage Load Calcs
#1
03-13-17, 02:16 PM
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Detached Garage Load Calcs
So in doing the whole house load calcs to figure if my panel can handle adding a detached garage, how exactly do I treat the garage? As it stands today, my calculation for my whole house is 124 amps, I'm on 150 amp service. Do I add the square footage to the total load? I don't plan to hard-wire anything in the garage. If so any additional amperage used by the garage would fall into the 40% group as 100% only applies to the first 10kW.
#2
03-13-17, 02:27 PM
Are you planning on running power to the garage is why you are doing load calcs? You don't need to get all technical with the calcs using square footage. Just estimate the highest total load on the main panel at one time and then estimate the total highest load you anticipate at one time in the garage.
#4
03-13-17, 02:50 PM
Just guesstimate the most power you will ever use at any one time. Pick Thanksgiving, you have a mess of people over and are cooking the big dinner. Every burner on the range is running, a coffee pot perking away, maybe a toaster oven and the microwave along with the lighting. Now, with all these people in the way do you think you are going to go out in the shop and do some arc welding?
#5
03-13-17, 02:53 PM
Oh it's good to do some estimates of the loads but you don't need to get into the weeds doing it. If you have space in the main panel to add a DP breaker to feed the garage I'm confident you can add a 60A breaker to do so and will not have any issues. Now that is saying you don't have some uncommon high power usage in your home. Such as running a kiln or power lights to grow pot or on demand water heaters.
#6
03-13-17, 02:59 PM
Here is a great site if you are planning your garage. It covers everything from Electrical to Heat to Tools. The Garage Journal Board - Powered by vBulletin
#7
03-13-17, 03:03 PM
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Now, with all these people in the way do you think you are going to go out in the shop and do some arc welding?
Oh it's good to do some estimates of the loads but you don't need to get into the weeds doing it.
I just ordered a Murray 50A breaker, that should do well with whatever I'll be doing in the shop (moderate woodworking/aircraft building). Thanks
#9
03-13-17, 03:20 PM
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In case you aren't aware for power to the garage, you need a four wire feeder, isolated neutral in subpanel, and ground rods.
#12
03-13-17, 04:20 PM
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Yeah I should be good there. 3 #8 THWN red-black-white and a #10 ground, copper, in 1" sch 80 pvc at the building entrances, sch 40 for the run, rated for 50 amps at 75C, 75C breakers at both ends. #6 bare copper ground, unspliced, to two 8' rods at least 6' apart buried below grade. That's the plan so far.
