I realize many of you are professionals and I am likely to get numerous “Call an electrician…” responses, but I want to understand what I’ve got and best approach to get what I want after modifying existing circuitry. Here’s the existing condition… and yes I have contacted an electrician who is going to come to my location….
At my newly purchased house which we are remodeling (built circa 1968) I have the following set of panel/subpanels:
1 Main/primary/first Square D panel with a 200A breaker - two black 120V lines, one black w white stripe neutral conductor and one black ground wire from the meter directly adjacent. This panel and meter are mounted to an exterior brick wall outside the house, directly opposite a utility room with 3 secondary or subpanels. This panel supplies power to the three subpanels, all of which are Square D QO Load Center catalog number QO 12-24. They each have one black 120V black line, one red 120V line, and one large twisted aluminum wire connected to one (or both?) of the ground and neutral bars which are directly adjacent to one another. The bare aluminum wire runs back to the main panel.
One subpanel is fed by a 125V breaker and only has 120V “mini/narrow” Square D breakers. This subpanel has what appears to be separate but adjacent neutral and ground bars, but all the white neutrals and bare copper ground wires from the circuits are connected to just one of these…it’s packed.
The other two subpanels are each fed by a 100A breaker in the main. They have same black and red 120V lines inbound which have lugs at top and the twisted aluminum wire attached to one or both of the neutral and ground bars which are near the bottom of the panel box. Both of these other two subpanels only have 240V breakers. Each breaker serves an old ceiling mounted radiant heat system above each room. The circuits in these two panels consist of two wire Romex without a ground in the NM cable jacket. Each black and white wire carries 120V to a box and were connected at a controller (rheostat?) mounted in each room. From there the “heat wires” run up to the ceiling where they disappear into the Sheetrock. I presume they attach to a grid/mat embedded in the plaster layer over the Sheetrock. The heat wires and controllers will be removed. These two panels appear to have one green insulated ground wire for each breaker connected to one of the bars. These green wires enter the panel separately from the two wire Romex which connect to each breaker.
Finally, my objectives/questions:
1) I want to convert a number of the existing 240V radiant heating circuits to 120V circuits and use them to minimize the number of outlets/lights/appliances on the existing 120V circuits.
2) Can I use the two existing subpanels which only have 240V breakers by swapping out for 120V breakers? Connect white (now neutral) wire to the unoccupied bar?
3) I’m assuming I (and electrician) must ensure the neutral and ground bars are not bonded in the old 240V panels(?)
4) what about the existing subpanel with only 120V breakers - should we split up the neutrals and bare copper ground wires onto separate bars and ensure they are not bonded?
Appreciate your patience with the lengthy description and any suggestions. Tried to attach photos but couldn’t get it to work.
At my newly purchased house which we are remodeling (built circa 1968) I have the following set of panel/subpanels:
1 Main/primary/first Square D panel with a 200A breaker - two black 120V lines, one black w white stripe neutral conductor and one black ground wire from the meter directly adjacent. This panel and meter are mounted to an exterior brick wall outside the house, directly opposite a utility room with 3 secondary or subpanels. This panel supplies power to the three subpanels, all of which are Square D QO Load Center catalog number QO 12-24. They each have one black 120V black line, one red 120V line, and one large twisted aluminum wire connected to one (or both?) of the ground and neutral bars which are directly adjacent to one another. The bare aluminum wire runs back to the main panel.
One subpanel is fed by a 125V breaker and only has 120V “mini/narrow” Square D breakers. This subpanel has what appears to be separate but adjacent neutral and ground bars, but all the white neutrals and bare copper ground wires from the circuits are connected to just one of these…it’s packed.
The other two subpanels are each fed by a 100A breaker in the main. They have same black and red 120V lines inbound which have lugs at top and the twisted aluminum wire attached to one or both of the neutral and ground bars which are near the bottom of the panel box. Both of these other two subpanels only have 240V breakers. Each breaker serves an old ceiling mounted radiant heat system above each room. The circuits in these two panels consist of two wire Romex without a ground in the NM cable jacket. Each black and white wire carries 120V to a box and were connected at a controller (rheostat?) mounted in each room. From there the “heat wires” run up to the ceiling where they disappear into the Sheetrock. I presume they attach to a grid/mat embedded in the plaster layer over the Sheetrock. The heat wires and controllers will be removed. These two panels appear to have one green insulated ground wire for each breaker connected to one of the bars. These green wires enter the panel separately from the two wire Romex which connect to each breaker.
Finally, my objectives/questions:
1) I want to convert a number of the existing 240V radiant heating circuits to 120V circuits and use them to minimize the number of outlets/lights/appliances on the existing 120V circuits.
2) Can I use the two existing subpanels which only have 240V breakers by swapping out for 120V breakers? Connect white (now neutral) wire to the unoccupied bar?
3) I’m assuming I (and electrician) must ensure the neutral and ground bars are not bonded in the old 240V panels(?)
4) what about the existing subpanel with only 120V breakers - should we split up the neutrals and bare copper ground wires onto separate bars and ensure they are not bonded?
Appreciate your patience with the lengthy description and any suggestions. Tried to attach photos but couldn’t get it to work.