masterofnone
DIY
I would like to ask advice on a breaker size.
Back in 2001 I turned my garage into a woodworking shop with several 240v machines. To power them I put in a 100 amp subpanel supplied by an 80 foot run of 4 gauge romex (two hots, neutral and ground) from the main panel under the house to the garage. I used a 60 amp breaker at the main panel end, either out of caution or because I happened to have one, I forget. Since I'm the only one ever using the equipment, there is only ever one machine (max 30 amp circuit but more usually 20 amp) plus the dust collector (30 amp circuit) plus some ceiling lighting (originally flourescents, now LEDs) running at any given time. This has worked fine for 21 years, never tripped once.
Now we have just bought an electric car and I want to install a 48 amp Level 2 charger for it, powered off the same subpanel. With the 60 amp supply breaker I will not be able to run any of my shop tools while charging the car. So I want to upsize this breaker and my question is: how high can I go?
What I don't know is the insulation rating of the 4 gauge romex. I've looked at the exposed wires in the subpanel and don't see anything printed on the insulation. I haven't gone under to look at the romex sheathing yet--access is through the master bedroom closet--but I don't know if anything's printed on it either.
Can anyone suggest what was the common rating of this cable back in 2001 (sure am hoping THHN) and what would be the maximum safe breaker size I can use?
Back in 2001 I turned my garage into a woodworking shop with several 240v machines. To power them I put in a 100 amp subpanel supplied by an 80 foot run of 4 gauge romex (two hots, neutral and ground) from the main panel under the house to the garage. I used a 60 amp breaker at the main panel end, either out of caution or because I happened to have one, I forget. Since I'm the only one ever using the equipment, there is only ever one machine (max 30 amp circuit but more usually 20 amp) plus the dust collector (30 amp circuit) plus some ceiling lighting (originally flourescents, now LEDs) running at any given time. This has worked fine for 21 years, never tripped once.
Now we have just bought an electric car and I want to install a 48 amp Level 2 charger for it, powered off the same subpanel. With the 60 amp supply breaker I will not be able to run any of my shop tools while charging the car. So I want to upsize this breaker and my question is: how high can I go?
What I don't know is the insulation rating of the 4 gauge romex. I've looked at the exposed wires in the subpanel and don't see anything printed on the insulation. I haven't gone under to look at the romex sheathing yet--access is through the master bedroom closet--but I don't know if anything's printed on it either.
Can anyone suggest what was the common rating of this cable back in 2001 (sure am hoping THHN) and what would be the maximum safe breaker size I can use?
