Tap rule

[cloudibew]

Would someone please direct me to the "tap rule" stuff. I'd like to see if the existing vav stuff in this remodel are legit. 45amp ckt feeding multiple 15amp vav's however one branches off the #8 wire and shoots out 200' to a fused disc. I know the conductors should never see more than 15amps cause the fuse will pop. But the 200' has me questioning it.

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[petersonra]

Would someone please direct me to the "tap rule" stuff. I'd like to see if the existing vav stuff in this remodel are legit. 45amp ckt feeding multiple 15amp vav's however one branches off the #8 wire and shoots out 200' to a fused disc. I know the conductors should never see more than 15amps cause the fuse will pop. But the 200' has me questioning it.

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generally you cannot run a tap this far before terminating it at an OCPD. the sole exception I an aware of is if it is outside.

240.21

 

[cloudibew]

Cool your awesome thanks, any reference, i am a learn to fish kinda guy, as opposed to just being handed fish.

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[Pharon]

See 240.21.

 

[iwire]

Would someone please direct me to the "tap rule" stuff. I'd like to see if the existing vav stuff in this remodel are legit. 45amp ckt feeding multiple 15amp vav's however one branches off the #8 wire and shoots out 200' to a fused disc. I know the conductors should never see more than 15amps cause the fuse will pop. But the 200' has me questioning it.

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What size wire is being used for the 200'?

 

[cloudibew]

#10 to a fused disconnect fused at 15i, 3phase 480v vav.

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[petersonra]

Is 15 the fla of the motor? The ocpd can be 250% rounded up to the next std size cb. I got the impression that the cb at the end of the 200 foot run was what was 15 amps.

 

[cloudibew]

Its a vav 15amp is what its fused at. Im fairly certain its due to the heat strips, 480v, at this point i have already pulled out the 10's and pulled in 8's to accomodate the 45amp breaker feeding the circuit. I was wantig a reference so i could read up on it so i the future i can make a more effective choice based on fact not gut. I suspect that 200' is too far but i dont know for sure.

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[augie47]

Other than conductors outside the building, the tap rules (240.21) normally require conductors longer than 10 ft or 25 ft to be protected at a level no greater than their ampacity,

 

[Carultch]

Would someone please direct me to the "tap rule" stuff. I'd like to see if the existing vav stuff in this remodel are legit. 45amp ckt feeding multiple 15amp vav's however one branches off the #8 wire and shoots out 200' to a fused disc. I know the conductors should never see more than 15amps cause the fuse will pop. But the 200' has me questioning it.

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240.21(B) is the set of tap rules.
240.21(C) is a set of analogous rules for transformer secondary conductors.

A tap is a section of conductors that are protected, except only in excess of their ampacity. They do not get protected against overload, until terminating at an overcurrent device on the opposite end of the tap point.

The only case when you can tap a 200 ft of 1-way circuit distance from tap point to overcurrent device, is with an outside unlimited tap rule. 240.21(B)(5).

Indoors, you have to terminate within 10 ft or 25 ft of the tap point. Unless you can apply the very obscure 100 ft tap rule.

 

[cloudibew]

Yer awesome!! Thanks

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[kwired]

240.21(B) is the set of tap rules.
240.21(C) is a set of analogous rules for transformer secondary conductors.

A tap is a section of conductors that are protected, except only in excess of their ampacity. They do not get protected against overload, until terminating at an overcurrent device on the opposite end of the tap point.

The only case when you can tap a 200 ft of 1-way circuit distance from tap point to overcurrent device, is with an outside unlimited tap rule. 240.21(B)(5).

Indoors, you have to terminate within 10 ft or 25 ft of the tap point. Unless you can apply the very obscure 100 ft tap rule.

Keep in mind you may be able to create the equivalent of outdoor conductors by encasing a raceway or cable (if permitted to be encased) in at least 2 inches of concrete and then use the outside taps of unlimited length rule.