25 ft tap rule

[Peter Furrow]

A question came up regarding an installation and “tap rules”
article 240.21 B(2).
The apartment owner on the third floor wanted a Tesla charger. Polaris taps would be installed at the meter center after the 150 A main for the apartment. The number six copper feeder wire would be tapped off of the 2\0 Al going to the 3rd floor apt. That tesla feeder is only 4 feet so It wouldn’t be a violation. It transitions to a branch circuit and goes 50 feet to the charger and still will not be a violation. Correct?
However, Now that the feeder has been tapped for the third-floor indoor apartment panel and it’s 70 feet away this would violate the 25 foot tap rule. Correct?
My thought is that the violation is not so much the Tesla charger tap but the third-floor indoor panel has now become a tap and it’s over 70 feet

 

[Peter Furrow]

A question came up regarding an installation and “tap rules”
article 240.21 B(2).
The apartment owner on the third floor wanted a Tesla charger. Polaris taps would be installed at the meter center after the 150 A main for the apartment. The number six copper feeder wire would be tapped off of the 2\0 Al going to the 3rd floor apt. That tesla feeder is only 4 feet so It wouldn’t be a violation. It transitions to a branch circuit and goes 50 feet to the charger and still will not be a violation. Correct?
However, Now that the feeder has been tapped for the third-floor indoor apartment panel and it’s 70 feet away this would violate the 25 foot tap rule. Correct?
My thought is that the violation is not so much the Tesla charger tap but the third-floor indoor panel has now become a tap and it’s over 70 feet

Sent from my iPhone using Tapatalk

 

[winnie]

So it isn't a tap if it is protected at its ampacity. However the ampacity of 2/0 is less than 150A, thus the issue.

If the 2/0 carries the full load of a residence, it is kosher protected with a 150A breaker. But once the tap for the charger is added, then the 2/0 is clearly not carrying the full load.

If you have 2/0 service conductors then no feeder need be larger than 2/0, and you have that few feet of 2/0 which is carrying the full load of the residence, but I think you end up with a technical violation in a situation that is perfectly safe.

Jon

 

[petersonra]

2/0 AL ampacity is 135 A. It seems to me the next sized standard CB is 150A. So as long as the total calculated load is <= 135 A I think you are OK.

 

[winnie]

petersonra: good point.

I amend my statement: a feeder is not a 'tap' if it is considered protected by OCPD at its supply end.

2/0 AL with a calculated load of <= 135A is considered protected by a 150A OCPD, and thus not a tap.

2/0 AL carrying the entire load of a residence with a calculated load of <=150A is considered protected by a 150A OCPD, and thus not a tap.

If the calculated load of the apartment is > 135A, or the calculated load of the apartment plus the charger is > 150A, then the installation is not acceptable.

-Jon

 

[Peter Furrow]

petersonra: good point.

I amend my statement: a feeder is not a 'tap' if it is considered protected by OCPD at its supply end.

2/0 AL with a calculated load of
2/0 AL carrying the entire load of a residence with a calculated load of
If the calculated load of the apartment is > 135A, or the calculated load of the apartment plus the charger is > 150A, then the installation is not acceptable.

-Jon

So I have to calculate the load to determine if it’s acceptable. But as it stands , the feeders to the apartment panel do not fall under the 25 foot tap rule. Even though there is a Polaris tap on those panel feeders to provide power to the Tesla charger It still does not fall under the tap rule of 25 feet. At tap rule with only apply to the Tesla charger. That’s my take away from your comment. Correct me if I’m wrong


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[winnie]

So I have to calculate the load to determine if it’s acceptable. But as it stands , the feeders to the apartment panel do not fall under the 25 foot tap rule. Even though there is a Polaris tap on those panel feeders to provide power to the Tesla charger It still does not fall under the tap rule of 25 feet. At tap rule with only apply to the Tesla charger. That’s my take away from your comment. Correct me if I’m wrong

That is my understanding.

You have a 'feeder'. The 2/0 Al is protected on its supply end by the 150A breaker.

The feeder to the Tesla charger breaker is a 'feeder tap' because it is protected on its _load_ end by the 60A breaker.

The fact that the 2/0 Al has been 'tapped' does not make it a 'feeder tap' because it remains a 2/0 Al.

You need to do the calculations to make sure 1) that the 2/0 Al is in fact properly loaded and protected and 2) that the 150A service is itself not overloaded.

-Jon

 

[petersonra]

petersonra: good point.

I amend my statement: a feeder is not a 'tap' if it is considered protected by OCPD at its supply end.

2/0 AL with a calculated load of <= 135A is considered protected by a 150A OCPD, and thus not a tap.

2/0 AL carrying the entire load of a residence with a calculated load of <=150A 135A is considered protected by a 150A OCPD, and thus not a tap.

If the calculated load of the apartment is > 135A, or the calculated load of the apartment plus the charger is > 150A 135A, then the installation is not acceptable.

-Jon

fixed it. you can go up to the next highest rated CB but the ampacity of the conductors does not change.

 

[winnie]

fixed it. you can go up to the next highest rated CB but the ampacity of the conductors does not change.

I am open to being corrected, but I really did mean 150A. If the article 220 load calculation for the total load of a residence is 150A or less, then the '83% rule' applies. This would permit 2/0 Al protected by a 150A breaker with a calculated load of anything up to 150A.

-Jon

 

[petersonra]

I am open to being corrected, but I really did mean 150A. If the article 220 load calculation for the total load of a residence is 150A or less, then the '83% rule' applies. This would permit 2/0 Al protected by a 150A breaker with a calculated load of anything up to 150A.

-Jon

good point

 

[Eddie702]

I agree with @winnie

To meet code the existing feeder no longer carries the full load so they would have to be recalculated. But the easiest fix is to make the tap conductors the same ampacity as the existing feeder as mentioned above.

A good example of when common sense and the code do not coinside. I think most would agree that it would be perfectly safe with the #6 tap

 

[tom baker]

Thank you for the drawing, simple and readable.

 

[electricblue]