DIY USA old house 3 wire feed subpanel

[pstr8ahead]

I have an old 1959 house that appears to have outside service panel feeding 2 subpanels in the house each with only 3 wire feed. One subpanel(A) is in laundryroom supplying that side of house including kitchen, livingroom and half of den. The other subpanel(B) feeds 3 bedrooms, hallway and 2 bathrooms.

Both subpanels have neutral bonded to ground. I suppose this is how they used to do it. No outlets or fixtures I've seen have a ground. Receptacles have been changed to 3 prong but no ground.

Subpanel(A) only has 2 breakers feeding all receptacles on that side of house. I would like to add another subpanel to lighten the load with more 20A breaker for receptacles especially in the kitchen.

Question: If I add a subpanel(C) from subpanel(A) do I use 4 wire feed and start isolating neutral from that point or do I continue bonding neutral to ground in subpanel(C)?

I know I should upgrade both subpanels and run 4 wire feed from service panel to subpanels (A,B) but not really in the budget right now.

 

[Megawatt]

I have an old 1959 house that appears to have outside service panel feeding 2 subpanels in the house each with only 3 wire feed. One subpanel(A) is in laundryroom supplying that side of house including kitchen, livingroom and half of den. The other subpanel(B) feeds 3 bedrooms, hallway and 2 bathrooms.

Both subpanels have neutral bonded to ground. I suppose this is how they used to do it. No outlets or fixtures I've seen have a ground. Receptacles have been changed to 3 prong but no ground.

Subpanel(A) only has 2 breakers feeding all receptacles on that side of house. I would like to add another subpanel to lighten the load with more 20A breaker for receptacles especially in the kitchen.

Question: If I add a subpanel(C) from subpanel(A) do I use 4 wire feed and start isolating neutral from that point or do I continue bonding neutral to ground in subpanel(C)?

I know I should upgrade both subpanels and run 4 wire feed from service panel to subpanels (A,B) but not really in the budget right now.

Always use 4 wires when adding a sub panel and isolate neutrals from the ground wires.

 

[pstr8ahead]

Always use 4 wires when adding a sub panel and isolate neutrals from the ground wires.

Thanks for the reply. After thinking about it more I think I'd rather swap the existing panels instead of adding another.

I would like to upgrade subpanel(A) with a 200 amp panel with more circuits. Both existing panels are fed by what looks like 3-wire #2 or #3 Al each protected by a 70 amp breaker at main. I plan to run a 6awg copper bond wire from main neutral/ground bar to new subpanel ground bar. I will separate existing neutrals and grounds in new panel.

Next year I would replace feeder run with 4/0-4/0-4/0-2/0 Al and swap breaker to 200 amp (the main has unused lugs I think I can feed straight from those and not need the extra breaker). I will then also upgrade subpanel(B) to a 100 amp panel and run appropriate 4-wires from 100 amp breaker in subpanel(A) to feed subpanel(B).

Is this a good plan? Will upgrading in stages like this be ok? I don't have the budget to do it all at once.

 

[Megawatt]

Thanks for the reply. After thinking about it more I think I'd rather swap the existing panels instead of adding another.

I would like to upgrade subpanel(A) with a 200 amp panel with more circuits. Both existing panels are fed by what looks like 3-wire #2 or #3 Al each protected by a 70 amp breaker at main. I plan to run a 6awg copper bond wire from main neutral/ground bar to new subpanel ground bar. I will separate existing neutrals and grounds in new panel.

Next year I would replace feeder run with 4/0-4/0-4/0-2/0 Al and swap breaker to 200 amp (the main has unused lugs I think I can feed straight from those and not need the extra breaker). I will then also upgrade subpanel(B) to a 100 amp panel and run appropriate 4-wires from 100 amp breaker in subpanel(A) to feed subpanel(B).

Is this a good plan? Will upgrading in stages like this be ok? I don't have the budget to do it all at once.

Yes my friend you are definitely on the right track. I’m glad you are doing this it better to be safe than sorry