Ten foot tap rule

[Dale001289]

Can the tapped conductor based on the ampacity of upstream CB trip setting in lieu of the rating of the CB?


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[charlie b]

Sorry, but I don't understand your question. For starters, circuit breakers don't have "ampacity." Also, you mention "trip setting" and "rating of the CB." I am not sure what that means. Please try to restate the question more clearly.

 

[Dale001289]

Sorry, but I don't understand your question. For starters, circuit breakers don't have "ampacity." Also, you mention "trip setting" and "rating of the CB." I am not sure what that means. Please try to restate the question more clearly.

The Cb has an adjustable trip. It’s rated 600A, but the trip is set at 400A. For 10’ tap you can base the tapped conductores on ten percent of the CB protecting the feeder. So is that ten percent of 600 or ten percent of 400?


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[jim dungar]

The Cb has an adjustable trip. It’s rated 600A, but the trip is set at 400A. For 10’ tap you can base the tapped conductores on ten percent of the CB protecting the feeder. So is that ten percent of 600 or ten percent of 400?


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Ten percent of the setting, if the settings can be 'locked'.

 

[charlie b]

Thank you for clarifying. I understand what you mean, and I see that the code wording "appears" to give us a choice. But I don't think it does.

Jim posted while I was typing. I was unaware that settings can be permanently locked. Not knowing that, my answer would have been 600. The words are rating of the OCPD. The CB rating is 600, whatever setting is selected.

 

[jim dungar]

Thank you for clarifying. I understand what you mean, and I see that the code wording "appears" to give us a choice. But I don't think it does.

Jim posted while I was typing. I was unaware that settings can be permanently locked. Not knowing that, my answer would have been 600. The words are rating of the OCPD. The CB rating is 600, whatever setting is selected.

The settings do not need to be permanently locked.
The NEC allows something as simple as a cover over the setting adjustments that can be sealed with a cable tie.

This is similar to using fuses smaller than the full rating of a fusible switch.

 

[Dale001289]

The settings do not need to be permanently locked.
The NEC allows something as simple as a cover over the setting adjustments that can be sealed with a cable tie.

This is similar to using fuses smaller than the full rating of a fusible switch.

This is very enlightening. thanks


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[letgomywago]

The settings do not need to be permanently locked.
The NEC allows something as simple as a cover over the setting adjustments that can be sealed with a cable tie.

This is similar to using fuses smaller than the full rating of a fusible switch.

That's a good point for this kind of thing.

 

[Isaiah]

The settings do not need to be permanently locked.
The NEC allows something as simple as a cover over the setting adjustments that can be sealed with a cable tie.

This is similar to using fuses smaller than the full rating of a fusible switch.

Makes sense, I never would have thought of that.


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[augie47]

FWIW, your CODE reference is 240.6 (B)& (C)

 

[kwired]

The settings do not need to be permanently locked.
The NEC allows something as simple as a cover over the setting adjustments that can be sealed with a cable tie.

This is similar to using fuses smaller than the full rating of a fusible switch.

Unfortunately someone very well may increase the fuse size someday, or cut the lock and increase breaker setting

 

[letgomywago]

Unfortunately someone very well may increase the fuse size someday, or cut the lock and increase breaker setting

This has been discussed though. You can jam copper pipe into a fused disconnect too. A line has to be drawn it was already

 

[qcroanoke]

This has been discussed though. You can jam copper pipe into a fused disconnect too. A line has to be drawn it was already

I once seen a 100 amp meter socket jumped out with box fasteners. (F straps)

 

[letgomywago]

I once seen a 100 amp meter socket jumped out with box fasteners. (F straps)

Thar the battleship blows!!!