10 Foot Tap Rule, How does it apply to this?

[ChillSparky]

What I have is a 3 Phase Delta 208V 200 Amp Disconnect after a meter. The Disconnect originally and still does feed a 200A Cutler Hammer panel directly behind it inside of the building. We were hooking up a rather large cooler with max OCP of 90A. Just to the left of the first disconnect (the one feeding the inside panel) we set a 100A fusible disconnect with a set of 90A fuses. This is approximately 6 ft from lug to lug for the conductor length. In order to comply with the 10ft tap rule, what side of the 200A Disco can we tap from? And why would an inspector require us to match the conductor size that serves the 200A Disco? I believe we had #4 feeding the 90A, which is within the 1/10th of the conductor size 3/0. I'm confused as to how and when 240.21 can be applied. Thanks in advanced guys!!

 

[jumper]

Are both disconnects and the tap conductors outside? If so, then 240.21(B)(5) would apply and not 240.21(B)(1) and it looks like that #4 CU is good for 85A, but 240.21(B) states that 240.4(B) cannot be applied, so it seems that you may be non-compliant.

 

[david luchini]

You could apply 240.21(B)(1) for a 10' tap from the load side of the 200A disconnect.

However, from your description, your tap is incorrect. You indicated #4 tap conductors (with an ampacity of 85, assuming copper) terminating at 90A fuses. This does not comply with 240.21(B)(1)(1)b. You would need to change the fuses to 80A, or increase the tap conductors to #3.

 

[jumper]

You could apply 240.21(B)(1) for a 10' tap from the load side of the 200A disconnect.

However, from your description, your tap is incorrect. You indicated #4 tap conductors (with an ampacity of 85, assuming copper) terminating at 90A fuses. This does not comply with 240.21(B)(1)(1)b. You would need to change the fuses to 80A, or increase the tap conductors to #3.

But don't the tap conductors for the 10' rule not have to leave the equipment enclosure? It sounds like they do in the OP.

 

[ChillSparky]

To correct myself, the disconnect was fused at 85Amps not 90 and conductors are copper. The tap does leave the first disconnect, protected in conduit of course. Both disconnects are outside as well. I see where maybe #4 may not be the correct size, being the condensing unit is rated for 90A, even though it is fused at less. I really appreciate all the quick responses.

 

[infinity]

Are you connecting on the line side of the 200 amp service disconnect?

 

[david luchini]

But don't the tap conductors for the 10' rule not have to leave the equipment enclosure? It sounds like they do in the OP.

Do you mean the equipment enclosure where they originate or where they terminate? I don't think there is a prohibition against the tap conductors leaving the enclosure where they originate. And leaving the enclosure where they terminate, he has a new properly protected feeder or branch circuit.

 

[ChillSparky]

Are you connecting on the line side of the 200 amp service disconnect?

It was attached at the load side of the 200 amp service disconnect. I think I will bite the bullet and use 1/0, even though I do think with just some minor changes it would fall under the 10 ft rule.

 

[jumper]

Do you mean the equipment enclosure where they originate or where they terminate? I don't think there is a prohibition against the tap conductors leaving the enclosure where they originate. And leaving the enclosure where they terminate, he has a new properly protected feeder or branch circuit.

As usual, you are correct.

I misread these sections:slaphead::

(2) The tap conductors do not extend beyond the switchboard,
panelboard, disconnecting means, or control devices
they supply.
(3) Except at the point of connection to the feeder, the tap
conductors are enclosed in a raceway, which shall extend
from the tap to the enclosure of an enclosed
switchboard, panelboard, or control devices, or to the
back of an open switchboard.

 

[infinity]

Since your taps are completely outside then 240.21(B)(4) would apply and there is no restriction as to their length. All you need is use a conductor that is sized for the ampacity of the OCPD at the end of the tap. The conductors after the OCPD can be sized according to the MCA of the unit.

 

[jim dungar]

... what side of the 200A Disco can we tap from? ...

Because this is a 'service disconnect' (you said it was after the meter), a line side connection would be subject to the services rules in 230, and a load side connection would be subject to the rules in 240.

I believe, the others are correct in their suggestion that 240.21(B)4.

 

[ChillSparky]

Thank you all very much. So I will tap load side and size it for the OCPD I am connecting to. I really appreciate the help on this one. Tap rules are a bit tricky.