Taping off subpanel feed wire

[firebird1988]

Working on solar system for a cleint.

Now this inverter does not backfeed at all.

It only powers up the subpanel when the grid goes down aka battery backup. It will use the grid to charge batteries. I was thinking of installing a manual bypass switch for easy repair.



This is a unique setup as this client has his subpanel in a shed that is 300ft away from his main panel. Which powers up his well pump and lights/outlets. I rarely use wire taps and know very little about them. The tap will be right at the shed feed wire which will be located in a bypass switch box. Within 10ft from inverter/subpanel. It will run to the input power of the inverter. Inverter has a 80a input breaker. Now his subpanel doesnt have a main shut off breaker so I was going to throw in a 100a main shutoff breaker. Since it's a detached building it should require one then even though it is less then 6 circuits. All wires will be in a raceway. Can I do it like this or do I just need to add a another sub panel in the mix?



Trying to figure out how to post a picture of the design

 

[jaggedben]

I don't understand the design well enough from your description.

How does the inverter and subpanel disconnect from the grid when power is out?

 

[firebird1988]

Inverter has a built in auto transfer switch. Once it detects grid loss it switches over to battery power.

Inverter has 2 hook ups.
"Input "power from the grid.
"Output" power. Which is wired up directly to the subpanel or in this case lower half of a manual bypass switch. While the top half of the switch is grid power.

Normally I install theses inverters next to the main panel and add a subpanel which I bring the Critical loads over to the new designated subpanel.

 

[firebird1988]

Here is a diagram. My big question is the wire tap work in this location or if I should just add another subpanel into the mix. Again it's 300ft away from main breaker panel. Wire tap area will be within 10ft mark from sub panel and main breaker panel. Inverter has a built in breaker that should work for the downstream disconnect means for the wire tap rule if I am understanding it correctly. Inverter has auto tranfer switch. Manual bypass is for if the inverter ever failed. Again does not backfeed. It's a hybrid power inverter.

 

[jaggedben]

The tap is allowed but you need a disconnecting means and overcurrent device between the tap point and the inverter.

 

[firebird1988]

The tap is allowed but you need a disconnecting means and overcurrent device between the tap point and the inverter.

Great news! saves a lot of time. The inverter has a built-in 80a 2 pole breaker. (Input side) thank you for your help. I never use taps as it's vary vague in the books. I dont even recall if my instructors bqck in the day really even talk about them. Kind like voodoo Subject.

 

[wwhitney]

The tap is allowed but you need a disconnecting means and overcurrent device between the tap point and the inverter.

I'm not necessarily seeing a feeder tap in the diagram. There's a #2 Al (90A 75C ampacity) with #4 Cu (85A 75C ampacity) spliced to it.

If the main service is 100A residential, then the above is all good for a 100A feeder, no tap.

If the main service is not residential or is larger than 100A, the 100A OCPD for the #2 Al is too large. Unless the #2 Al is itself a tap that is completely outside and so may be of unlimited length. In which case the #2 Al needs to land on a 90A breaker.

Or the 100A breaker could be downsized to 90A, then it would protect both the 90A ampacity and 85A ampacity sections, and there's no feeder tap. Which works as long as the calculated load is 85A or less.

Cheers, Wayne

 

[firebird1988]

Yes I notice that too on wire gauge size. I just circled where i would tap it on my poorly drawn picture its not a splice as aluminum wire runs to bypass switch(on,off,on) .They have another violation I notice on the current subpanel in place. They don't have a main disconnect switch. Which the state has adapted 2020 nec. If you dont know but the 2020 nec rule got rid of the 6 or less circuit doesnt require one. So I am going pop in a 80a breaker up stream and down stream.

Sad thing is this cleint had electric hooked up last month so A inspector doesn't know the new rule or even looked.