Tap from the Service Switchboard

[Grouch1980]

Hi all,
If you drill into the bus of an existing Service Switchboard, provide a new tap, and provide wiring from the new tap to a new Service Switch (not integral to the switchboard), do the tap rules from Article 240 (10 foot / 25 foot tap rules) apply? These are feeder taps, so i'm assuming it doesn't apply, since in this application we're not tapping from a feeder, but from the service bus bars in the switchboard. If they don't apply, how far can the new Service Switch be installed from the new taps in the Service Switchboard?

 

[infinity]

If you're conductor connection is upstream of the service disconnect then the feeder tap rules do not apply and your conductors are service conductors. The NEC does not say how far those conductors can extend into the structure so it's up to the AHJ to decide. If the distance is long you could encase the raceway in 2" of concrete and the conductors are then considered outside of the buidling.

 

[electrofelon]

Take a look at 230.40 ex#2 and 230.70-72.

Also note that drilling a bussbar is generally frowned upon. I would try replace existing lugs, add lugs at bolt joints or existing holes, or see if the manufacturer has a clamp-on option.

 

[Grouch1980]

If you're conductor connection is upstream of the service disconnect then the feeder tap rules do not apply and your conductors are service conductors. The NEC does not say how far those conductors can extend into the structure so it's up to the AHJ to decide. If the distance is long you could encase the raceway in 2" of concrete and the conductors are then considered outside of the buidling.

Yes, the connection is upstream of the service disconnect. Yeah I figured those tap rules are for feeders only, and wouldn't apply here. Thanks for confirming!

 

[Grouch1980]

Take a look at 230.40 ex#2 and 230.70-72.

Also note that drilling a bussbar is generally frowned upon. I would try replace existing lugs, add lugs at bolt joints or existing holes, or see if the manufacturer has a clamp-on option.

Noted. I'll look into the existing holes or clamp-on as options. 230.40 ex. #2 that you reference, which code cycle? just to make sure i'm looking at the same thing.

 

[electrofelon]

Noted. I'll look into the existing holes or clamp-on as options. 230.40 ex. #2 that you reference, which code cycle? just to make sure i'm looking at the same thing.

I don't think 230.40 exception 2 has changed in any of the recent code cycles. It is sort of "the tap rule for services" (along with 230.70-72, 230.46, )

 

[Grouch1980]

I don't think 230.40 exception 2 has changed in any of the recent code cycles. It is sort of "the tap rule for services" (along with 230.70-72, 230.46, )

yeah, i checked the 2008 code and the 2017... they're the same. thanks!