Add 220V power tool circuit to existing sub-panel

[Dave Millman]

My workshop sub-panel is powered from two dedicated 110V 40A breakers off the main panel 100 feet away. The sub-panel has adjacent open breaker slots available. The four existing 110V 15A breakers supply lighting and outlets.

Can a 220V circuit be added to the sub-panel for a new power tool? The tool is rated at 220V, 1Ph, 7.5A.

Thank you.

 

[Reach4]

My workshop sub-panel is powered from two dedicated 110V 40A breakers off the main panel 100 feet away.

A subpanel is normally powered from a double pole breaker, and not two separate breakers. You will need to change that before adding a 240 volt circuit out of the subpanel.

 

[Sponsor]

 

[Fitter30]

Sub panel 40 amps wired from house with #8 wire?

 

[Afjes]

My workshop sub-panel is powered from two dedicated 110V 40A breakers off the main panel

A subpanel is normally powered from a double pole breaker, and not two separate breakers.

Two individual circuit breakers is acceptable (and meets code) for 240 circuits (and to feed sub panels) as long as there is a tie bar linking the two breakers. This ensures that the two breakers are on opposite legs of the service and also it will make you shut off both if needed to.

Yes, a 240 volt circuit can be added to the sub panel. You say the tool (240v) is 7.5 amps. However, will it trip the sub panel main breaker? We don't know what you will be running off the other 15amp breakers (at the same time) but I would think you would not have everything running at the same time. Normally a "load calculation" is done to see if the service (the sub panel in this case) will accept the load of 7.5amps but I would think it would. You would have to be running other tools at full load amp rating of the receptacles to trip the 40amp breaker in the main panel feeding the sub panel.

What 240v tool are you going to be using on the workshop circuit you are adding so you know the proper receptacle to install on the circuit. Does the tool/device have a name plate on it? If so can you take a pic of it and post it this way we can guide you as to what you need to install for a breaker, gauge wire/cable and the proper receptacle.

 

[Dave Millman]

Does the tool/device have a name plate on it? If so can you take a pic of it and post it this way we can guide you as to what you need to install for a breaker, gauge wire/cable and the proper receptacle.

It’s a bandsaw. I don’t have easy access to the tool right now, but this is from the manufacturer: