"Service rated" sub panel main breaker

[bbartmasse r]

Hello, I'm new to the forum, thanks in advance!

I want to back feed 40 amps onto a 100 amp sub panel. I know I have to downsize the main to an 80 amp breaker. Problem is I just discovered that the sub panel is not fed from a breaker from the main panel, it is tapped off of the service conductors (pardon me if my terminology is not perfect here). My boss says I need an 80 amp breaker that is "service rated." Another source says that should not be necessary and that the standard QO 80 will be fine as long as I install a hold down kit.

Any thoughts on this.

Thanks

 

[Dennis Alwon]

Hello, I'm new to the forum, thanks in advance!

I want to back feed 40 amps onto a 100 amp sub panel. I know I have to downsize the main to an 80 amp breaker. Problem is I just discovered that the sub panel is not fed from a breaker from the main panel, it is tapped off of the service conductors (pardon me if my terminology is not perfect here). My boss says I need an 80 amp breaker that is "service rated." Another source says that should not be necessary and that the standard QO 80 will be fine as long as I install a hold down kit.

Any thoughts on this.

Thanks

A hold down kit is sufficient to satisfy code

 

[Carultch]

Hello, I'm new to the forum, thanks in advance!

I want to back feed 40 amps onto a 100 amp sub panel. I know I have to downsize the main to an 80 amp breaker. Problem is I just discovered that the sub panel is not fed from a breaker from the main panel, it is tapped off of the service conductors (pardon me if my terminology is not perfect here). My boss says I need an 80 amp breaker that is "service rated." Another source says that should not be necessary and that the standard QO 80 will be fine as long as I install a hold down kit.

Any thoughts on this.

Thanks

If at all possible, I recommend using a QOB breaker instead of a QO breaker with hold down kit. Granted, this needs to be compatible with the panelboard. It is not compatible with load centers.

The hold down kit certainly meets code. The intent of the requirement to fasten a "backfed" breaker is to provide an additional safeguard in the event that the normally load-side terminals remain energized after the stabs are disconnected from the busbar.

Circuit breakers dedicated to an inverter, or a subpanel of inverters plural, albeit backfed, are a different story. Because the inverter shuts off upon the absence of continuity to the grid. For the branch breaker used as a main breaker in an AC combining panelboard, I recommend fastening it, because it remains energized by the grid when the breaker comes loose.

705.12(D)(6), “Fastening.” Dedicated ac inverter circuit breakers that are backfed from identified and listed utility-interactive inverters do not need to be secured in place by an additional fastener as required by Section 408.36(D).

 

[GoldDigger]

If there were not an explicit exception for a line side PV disconnect, you would have needed a service rated panel and breaker.
And if there are also normal loads in the panel I would call it a second main rather than a sub panel and probably illegal before the PV was added. And arguably after!

 

[bbartmasse r]

If there were not an explicit exception for a line side PV disconnect, you would have needed a service rated panel and breaker.
And if there are also normal loads in the panel I would call it a second main rather than a sub panel and probably illegal before the PV was added. And arguably after!

Second Main does sound more appropriate. Can you elaborate on thinking this an illegal setup? Service conductors come into a box, Smaller ALUM conductors are tapped here and feed second Main's 100 Amp breaker in a panel to the right, Service conductors continue to a 200 Amp shutoff to the left and on the Main panel in the house. I can try to post a picture if that would help. Thanks

 

[GoldDigger]

Second Main does sound more appropriate. Can you elaborate on thinking this an illegal setup? Service conductors come into a box, Smaller ALUM conductors are tapped here and feed second Main's 100 Amp breaker in a panel to the right, Service conductors continue to a 200 Amp shutoff to the left and on the Main panel in the house. I can try to post a picture if that would help. Thanks

What is needed for code compliance is that with no more than six handle motions, and without going into the house to the panel there, you can turn off all utility power to the house.
Does your setup meet that? If so it is probably OK.
If the inside panel is fed from the 200A disconnect, it should be alright.