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electrical sub-panel question - mound - 04-19-2021
Looks like a move to a new house may be in our near future.
In my current home I ran a 100amp sub-panel to my garage off the main 200 amp panel do power the garage wood shop.
The potential new house also has a 200amp main panel, but there already exists a 100amp sub-panel that was put in place to power an addition to the home at some point in the past. Could I still run another (a third) sub-panel into the garage from the main panel?
RE: electrical sub-panel question - MT Woodworker - 04-19-2021
Call your electrician....
As I am sure you know, electrical can start fires and yes kill folks.
Dealt with electrical fires on transport category aircraft, bad news.
RE: electrical sub-panel question - Splinter Puller - 04-19-2021
(04-19-2021, 08:09 AM)mound Wrote: Looks like a move to a new house may be in our near future.
In my current home I ran a 100amp sub-panel to my garage off the main 200 amp panel do power the garage wood shop.
The potential new house also has a 200amp main panel, but there already exists a 100amp sub-panel that was put in place to power an addition to the home at some point in the past. Could I still run another (a third) sub-panel into the garage from the main panel?
Sure you can. They are all breaker-ed at the main along with the main so if by some rare instance you ran too much draw it would trip the main at 200 amps. or the individual subpanel breaker at 100 amps.
Just run the main feeds large enough.
RE: electrical sub-panel question - MT Woodworker - 04-19-2021
Are you going to get a permit the new panel?
RE: electrical sub-panel question - TDKPE - 04-19-2021
There is no rule as to how much ampacity you can put in subpanels. If you put a shop in your basement and ran some new circuits to power it, or ran a feeder to a subpanel, the service is still providing the same power.
What matters is the connected load that's actually drawing current. You could, and probably do or will, have 400A worth of circuits, but they don't draw full power or more but rarely (motor starting, for instance), they don't usually even draw normal load very often (general purpose receptacle circuits all around the house), and many are seasonal where your furnace and/or space heaters don't run when the A/C is running.
If you want to analyze your system, use the NEC worksheet for service sizing to see where you are. But in most normal houses, like those that aren't running a grow operation in the basement (
), the average power draw is actually quite puny. Like 2000 kWh/mo, which averages to something like 12A at 240V (out of 200A at 240V in my case) or 24A at 120V. Slapping an ammeter on the incoming service conductors will also show surprisingly low typical current at any point in time.But to be honest, the average home shop doesn't actually need much power unless you're running a high output arc welder with electric resistance heat, and even then, it's mostly intermittent except for the heat.
[attachment=34911]
RE: electrical sub-panel question - mound - 04-19-2021
(04-19-2021, 09:45 AM)MT Woodworker Wrote: Are you going to get a permit the new panel?
I will ask if it's required.. When I did so on my existing property (same town as new property) they told me no permit was required. I did still get an inspection
RE: electrical sub-panel question - mound - 04-19-2021
(04-19-2021, 10:00 AM)TDKPE Wrote: There is no rule as to how much ampacity you can put in subpanels. If you put a shop in your basement and ran some new circuits to power it, or ran a feeder to a subpanel, the service is still providing the same power.
What matters is the connected load that's actually drawing current. You could, and probably do or will, have 400A worth of circuits, but they don't draw full power or more but rarely (motor starting, for instance), they don't usually even draw normal load very often (general purpose receptacle circuits all around the house), and many are seasonal where your furnace and/or space heaters don't run when the A/C is running.
If you want to analyze your system, use the NEC worksheet for service sizing to see where you are. But in most normal houses, like those that aren't running a grow operation in the basement (
But to be honest, the average home shop doesn't actually need much power unless you're running a high output arc welder with electric resistance heat, and even then, it's mostly intermittent except for the heat.
Thanks!
RE: electrical sub-panel question - TDKPE - 04-19-2021
(04-19-2021, 10:07 AM)mound Wrote: Thanks!
You're welcome. If that image is too hard to read, which the forum image function seems to do, PM me and I'll email a crisp file. The 2MB+ file was too big to post.
RE: electrical sub-panel question - MT Woodworker - 04-19-2021
I did 100 amp in my shop
As my electrician said, much more capacity than you will probably ever use
RE: electrical sub-panel question - TDKPE - 04-19-2021
(04-19-2021, 10:21 AM)MT Woodworker Wrote: I did 100 amp in my shop
As my electrician said, much more capacity than you will probably ever use
Almost certainly, unless you have electric resistance heat or other huge loads.
100A service is 200A of 120V power. Or 32 hp (electrical). It's a lot for a hobby shop. Or even a small commercial shop.