We are in the planning stages for a 40×40 detached garage / shop I am building and need to know what will be required in Everett, WA 98204 to bring power to the building.
- First off, I will need to run a high powered arc welder that currently is running off a 40A dual-pole breaker so that if I need to crank it up to its highest setting, I wouldn't have issues with the breaker popping when making long welds.
- The new shop will also have a dual stack oven that you normally find in a kitchen that we use for powder coating parts.
- Plus I want extra power available so if the oven is on, someone is welding, and someone else turns on the shop vac and all the lights, I am not popping breakers.
- I also plan to add even larger machine shop type equipment with time, like CNC machine, lathe, and mill (that's hopefully not going to require 3 phase).
I read other articles that say tie into the house breaker, which is only a 200A panel. I added up all the existing breakers as-is, which come to more than 200 amps. But I do not really know how much power would actually be drawn on each circuit if everything in the house was to be turned on, appliance and heat wise (all lights are already LED to conserve power, and heaters are all 220v in each bedroom).
For example, the kitchen lights are only a handful of LED bulbs and outlets with no real power being drawn, but has a 20A breaker. Same goes for nearly every circuit off that panel. So I am probably sure I could run a sub panel off it.
But let's say there are 4 roommates in the house running every appliance, plus 3 people in the shop doing the same. I don't know if that would equal more than 200 amps. But the last thing I want to do is risk it.
So my questions are:
- Can I run conduit off my meter on the outside of the house, instead of the existing house panel, and install another 150-200A panel 60' away in my shop?
- I would like the ability, over time, to add a bunch of machine shop equipment like CNC machine, lathe, mill, and etc without having to do all new electrical service to the shop again 2-3 years later. What should I do to not have future issues?
- Will conduit off the meter work instead of the house panel? If so what size conduit and cable to the new shop panel?
Best Answer
First. Next time you're welding and a breaker trips, put the tool down, walk away, and don't use the tool again until you have corrected the wiring defect (i.e. too-small wire for the tool and a breaker that is correct to protect that wire).
Talk to your power company about uploading that meter
Normally I would say "no way" because the meter itself and the service lateral (the pole line/underground from the transformer) would also need to have the capacity, and it usually doesn't.
However yours sounds like an all-electric house. I've seen all-electric houses provisioned for 400A. So it's possible the power company has already dropped a service lateral fit for 400A. In which case yeah, you could feed a second 200A main breaker right next to the meter pan and have that feed the garage.
Otherwise you will need to upgrade service, and depending on costs you may be better off getting a separate drop/meter.
This is completely determined by the power company and their peculiar situation on your block, we cannot possibly advise you other than to talk to them.
Given a project of this scope and safety impact, it goes without saying that you must communicate with the power company and must also pull permits with your local AHJ and do the inspection rigmarole. Generally AHJs are ok with people doing their own work, provided they are not a landlord (in which case no) or working commercially (in which case maybe). Doing this "gypsy" is out of the question.
You need to know more about exactly what your loads are
It sounds like you have only a coarse grasp of the electrical loads in your house. It is time for you to do a proper survey.
You are looking for watts or VA and need to eventually turn that into amps by dividing by volts. For instance a 2000W heater which runs on 240V is -- anyone, anyone, Bueller? 8.3333 amps at 240V.
For a resistive heater, Watts and VA are identical. For most others, VA is more important - Watts is what you pay for, VA is what trips the breaker. (to be more precise, VA is the power you must provision.) When different, use VA.
Get the numbers off the machines' nameplates. If no nameplate and they plug in, just get a $30 Kill-a-Watt and measure the machine underway. You'd be surprised what is almost nothing (coffee grinders) and what is a lot (coffee makers). Kill-a-Watt is not as helpful as nameplate, because nameplate is professionally tested.
Motors are special; get their running amps and horsepower. Locked rotor amps (a rather large number compared to the others) is not that important, nor is RPM.
Make a spreadsheet of the whole kit-n-kaboodle, you can do 240V and 120V loads separately. Then think about what is likely to be on at the same time (NOT heat and A/C hopefully) but even moreso, in the shop. Do you expect to use the lathe and planer at the same time?
Once you have done this survey, a bunch of really educational numbers will fall out the bottom and you'll know what to do next.
Think more about conservation
LED bulbs are nice, but it is "rearranging deck chairs on the Titanic" if you have resistive electric heat. I would go one of two ways on that. One is convert your resistive heaters to heaters that mine Bitcoin - you're still using a lot of electricity but at least you're getting paid. The other is go heat pump, which is ideal in a place freezes are rare; this will greatly lower your energy consumption and give you more headroom to run the shop.