HI.
I have a 100 amp service panel in my home. What is the largest subpanel breaker I can use on this setup. This is for a garage/shop running small compressor, battery charger, small benchtop tools, 3/4hp 110 lathe, 3/4 hp 110 mill, small welder, but not all at once.
Can I run 100 amps or should it be less than the main.
Thanks for you advice,
Lyle

You can use a 100 amp breaker if you like. The issue is the chance of overloading your 100 amp main.

On all machinery you have a ID tag telling you what the machine uses for instance, 120 volts/ 15 amps 230/240 V/ 6.5 amps.. Lesser voltage requires more amps, ( @ 120 V you might use 15 amps,but when you hook it up using 240 you'll use approx. 1/2 the power or amps ) look at your highest recommended amp output from your choice of all your tools, if it's say 30 amps, put a 50 or 60 in to be safe. Like you said, you can only use 1 at a time plus the lighting... You should be safe

Thanks TK,
I doubt if I'll ever use 100 amps but wanted to make sure it's feasible.
Cheers,
Lyle

To begin with you are going at this backwards.

You need to calculate the anticipated load for your shop and then size the feeder cable and breaker for that amount or slightly larger.

For example you may only need 40 or 50 amps in the shop and not 100 amps.

Next you need to make sure that the existing panelboard allows for the size breaker you want to use.

I seriously doubt that a manufacturer of a 100 amp. Panelboard is going to allow a 100 amp breaker to be used. Call the manufacturer and verify this.

While it is possible, it would be a bad to do that.

Thanks guys for all your answers. Small 30 amp welder would be the highest amperage item so I will go with the 60 amp which will be cheaper as well. I look at the size of #3 wire and can't imagine a breaker with that size lugs.
Anway, thanks again
Lyle