Tap rules? Can anyone help?

Status
Not open for further replies.
R

rayseeger

Member
Location
Virginia
I've been in the field a while but never applied the tap rules anywhere. I'm doing a job where a commercial building has a 400 amp service and wants a 100kw generator. The existing service splits below the meter with 3/0's going left and right to 2 200 amp fused disconnects, back into the same box below the meter and out the back to 2 200 amp panels. I need to put in a 400 amp transfer switch and feed the 2 200 amp panels.
First , can the service conductors pass thru the same box mounted below the meter? The code says they cant be in the same cable or raceway.
Second , can i apply the 10 foot tap rule , put a junction box on the 2 2" pipes near the panels, call them parallel feeds, splice them, and run 1 set of 3/0's to each panel?
I believe I can but I've asked a few people and thew all said their not sure but they also have not dont much in the way of taps.

Some help please?
 
rayseeger said:
First , can the service conductors pass thru the same box mounted below the meter? The code says they cant be in the same cable or raceway.
Second , can i apply the 10 foot tap rule , put a junction box on the 2 2" pipes near the panels, call them parallel feeds, splice them, and run 1 set of 3/0's to each panel?
I believe I can but I've asked a few people and thew all said their not sure but they also have not dont much in the way of taps.

Some help please?
Click to expand...

Your description of what you're trying to attempt is very unclear.

Where's the transfer switch located?

Why do you want to pass the service entrance conductors through the box below the disconnects? Are we talking about the from the utility? Or the generator feeder?

How will you protect the parallel feeds from the 100kW generator and transfer switch to the (2) 200 amp panels?

etc.
 
From a technical point of view you are describing service entrance conductors. the 10 foot tap rule (if that is what you are looking at) is located in 240.21 an only appears to apply to branch circuits and feeders. But I agree with ike

it would be helpful if your question was a little more focused
 
I believe the tap rules can be applied to service entrance conductors.

For example, the service that the OP is describing seems to be a 400 amp service with 3/0 taps to (2) 200 amp disconnects.

240.21(B)

Conductors shall be permitted to be tapped...to a feeder.
 
Looking again 240.21(B)(1)(4) and (B)(2)(1) indicate a line side over current device needs to be present.
 
If your planning on keeping the existing (2) 200 amp service disconnects outside below the panel, then no you cannot splice the conductors in the j-box and call them parallel feeders. You'll have to rework the conductors from the meter base.

Rick
 
IMO, the best option would be to replace each disconnect with a service-entrance-rated 200A transfer switch and be done with it.
 
Status
Not open for further replies.
Top