Replace Old ITE Imperial

Going to replace my old breaker panel(1972) with a Homeline SQ-D 125a equivalent. I'll keep it simple.

Because previous owners put incorrect breakers in there, tandems where tandems don't belong. There is some charring on some of the bus bar connectors. I removed those breakers and have empty space now.

Service(main) panel has 125a disconnect that connects to panel I am replacing via about 130' of 2/0 2/0 2/0(bare) al SER. Technically means it is a sub panel.

Question is can I just swap it out and keep the existing 3 wire system and let the neutrals and grounds share bonded bars and not isolate them (and leave out the green bonding screw) because this was the original design. I know it not is good as a 4 wire, but is it legal and safe( I know the new panel with be safer by defacto). If i need to add the 4th wire can it be a solo, or do I need to replace the whole thing with a 2/0-3 + ground? I have put in plenty of new sub's and always used 4 wire, but first time replacing an older panel.

 

Yes, that is a subpanel and the SER feeder is a 4-wire feeder. SER cable has 3 insulated conductors and 1 bare grounding conductor.

Your question makes no sense. What 3-wire system, you have a 4-wire SER cable feeder. The panel you are changing is in the same building as the 125 amp disconnect.....right?

 

Can you post a picture of the panels in question ?

 

I guess that was misleading. The Bare wire is the same size as the 2 mains, not smaller as the in the some bare(grounds), but there is only 3 wires. Here is the pic. And correction it is a 100amp breaker in the main and I am not going to swap that. Here is a pic.

 

This is up to the local inspector. Sometimes on what is strictly a panel swap (no increase in amps) and no change of the other service components, they will not make you replace the 3 wire feeder as it would be grandfathered as part of the original installation.

If you do need to install a new feeder, you would need to replace the entire cable with a four-conductor cable.

 

There is the problem, that isn't SER cable, but SEU cable.