Article 240.21.2

[Kyle S. Budd Jr.]

The question I have is were does the tap occur? Conditions 1, 2, and 3 of article 240.21.2 are met in this installation. We have an installation in a single family dwelling where there is a 400 amp main breaker transfer switch rated for service equipment that the taps supplies power to two 200 amp 120/240 volt single phase main breaker panels. The load side lugs of the transfer switch are a double barrel lug. We connected each tap conduct from the transfer switch load lug and terminated them to the main breaker in each panel. The transfer switch line lugs are fed from the utility meter with parallel 2/0. Our Authority is interpreting that we have to run 400 amp conductors or parallel 2/0 off the load lugs before we can make the tap with an approved lug or other connection. What is your thought on this?

Kyle S. Budd Jr.
Budd Electric Co. Inc.

 

[raider1]

Welcome to the forum.

Our Authority is interpreting that we have to run 400 amp conductors or parallel 2/0 off the load lugs before we can make the tap with an approved lug or other connection. What is your thought on this?

There is no need to run short sections of conductors and then tap off of them.

The lugs on the load side of the transfer switch would be the point that the tap could originate provided that the installation complied with one of the tap rules in 240.21(B).

Chris

 

[Pierre C Belarge]

Lets start with the definition of:

"Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4."

("this article" in the above paragraph is Article 240)


Since your conductors start at the termination in the lugs of the equipment, that is where the tap starts, based on the definition above.(I highlighted in blue what I thought would help in the understanding of this definition)


My question to you would be,
1. how long are those conductors? Remember the measurement is from termination to termination.

2. What wiring method did the installer use?

 

[don_resqcapt19]

It appears to me that these are still service conductors. If that is the case the rules in 240.21 do not apply. See the definition of a tap conductor as posted by Pierre in the post above.
Where are the 200 amp panels in relation to the transfer switch? Assuming they are immediately adjacent to the transfer switch as required by 230.91, it is my opinion that as long as the conductors between the transfer switch and the panels have an ampacity of 200 amps or more you are in complinace with the code.

 

[raider1]

It appears to me that these are still service conductors. If that is the case the rules in 240.21 do not apply. See the definition of a tap conductor as posted by Pierre in the post above.
Where are the 200 amp panels in relation to the transfer switch? Assuming they are immediately adjacent to the transfer switch as required by 230.91, it is my opinion that as long as the conductors between the transfer switch and the panels have an ampacity of 200 amps or more you are in complinace with the code.

I read that there was a 400 amp main breaker upstream, and therefore this was a feeder tap.

Chris

 

[Kyle S. Budd Jr.]

Lets start with the definition of:

"Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4."

("this article" in the above paragraph is Article 240)


Since your conductors start at the termination in the lugs of the equipment, that is where the tap starts, based on the definition above.(I highlighted in blue what I thought would help in the understanding of this definition)


My question to you would be,
1. how long are those conductors? Remember the measurement is from termination to termination.

2. What wiring method did the installer use?

The conductors are in 2 two inch conduits from the transfer switch to the main breaker panels. They are not adjacent to the transfer switch. One panel has 19 foot of conductor length and the other has 11 foot of conductor length.

 

[Pierre C Belarge]

It appears to me that these are still service conductors. If that is the case the rules in 240.21 do not apply. See the definition of a tap conductor as posted by Pierre in the post above.
Where are the 200 amp panels in relation to the transfer switch? Assuming they are immediately adjacent to the transfer switch as required by 230.91, it is my opinion that as long as the conductors between the transfer switch and the panels have an ampacity of 200 amps or more you are in complinace with the code.

Don
The OP mentioned a Service Rated Transfer Switch.

 

[Pierre C Belarge]

The conductors are in 2 two inch conduits from the transfer switch to the main breaker panels. They are not adjacent to the transfer switch. One panel has 19 foot of conductor length and the other has 11 foot of conductor length.

Kyle

It sounds like you have met the requirements for "tapping" based on 240.21(B).

The tap occurs at the loadside lugs.

 

[iwire]

Conditions 1, 2, and 3 of article 240.21.2 are met in this installation.

240.21(B)(2) Taps Not over 7.5 m (25 ft) Long. Where the length of
the tap conductors does not exceed 7.5 m (25 ft) and the tap
conductors comply with all the following:
(1) The ampacity of the tap conductors is not less than
one-third of the rating of the overcurrent device protecting
the feeder conductors.
(2) The tap conductors terminate in a single circuit breaker
or a single set of fuses that limit the load to the ampacity
of the tap conductors. This device shall be permitted
to supply any number of additional overcurrent devices
on its load side.
(3) The tap conductors are protected from physical damage
by being enclosed in an approved raceway or by other
approved means.

Our Authority is interpreting that we have to run 400 amp conductors or parallel 2/0 off the load lugs before we can make the tap with an approved lug or other connection.

There is nothing in the NEC to back up what the AHJ os asking for.

The only problem is they have not seen it before so they feel that it must be wrong.

 

[don_resqcapt19]

Don
The OP mentioned a Service Rated Transfer Switch.

I saw that, but missed the part that said the transfer switch had the service OCPD in it.

 

[Kyle S. Budd Jr.]

There is nothing in the NEC to back up what the AHJ os asking for.

The only problem is they have not seen it before so they feel that it must be wrong.

Do you know where I could go to get a formal interpretation? I spoke with our Authority again this morning and what he is saying is that this is not a tapped conductor if we connect to the load side of the 400 amp breaker. I have referred him to 240.4E.3 "Tap conductors shall be permitted to be protected against overcurrent in accordance with the following:---". We are on the load side of the service disconnecting means and as I stated earlier, all conditions of 240.21.B.2 are met. The Authority does not consider these Feeders, so the feeder tap rule would not apply unless we have a 400 amp conductor from the load side lugs and then perform the tap.

 

[don_resqcapt19]

Kyle,
Is he saying it is not a tap because it is directly connected to the breaker and not to a conductor? If so there is a recent thread on this issue.

As far as a formal interpretation, that takes months. You have to format a question that can be answered yes or no and send it to the NFPA. It then has to be circulated to the members of the code making panel that has authortity for that code section. The panel members have to vote on it just like the do on a code change proposal.

 

[don_resqcapt19]

Kyle,
Sorry..the thread I was talking about is in another forum. The closest thing to an FI is found in the panel's statement to a proposal that is in one of the posts on the second page.

 

[Kyle S. Budd Jr.]

Kyle,
Is he saying it is not a tap because it is directly connected to the breaker and not to a conductor? If so there is a recent thread on this issue.

As far as a formal interpretation, that takes months. You have to format a question that can be answered yes or no and send it to the NFPA. It then has to be circulated to the members of the code making panel that has authortity for that code section. The panel members have to vote on it just like the do on a code change proposal.

Yes, he is saying that it is not a tap so the tap rule does not apply.

 

[don_resqcapt19]

Yes, he is saying that it is not a tap so the tap rule does not apply.

The code making panel does not agree. See the panel comment on the proposal that is posted in the other forum.

 

[Kyle S. Budd Jr.]

Kyle,
Sorry..the thread I was talking about is in another forum. The closest thing to an FI is found in the panel's statement to a proposal that is in one of the posts on the second page.

Thank you for your help. I went to the other forum and found the panels statement and plan on showing it to our authority tomorrow. I am assuming this was a 2008 proposal.

 

[don_resqcapt19]

It was a proposal for the 2011 code.

 

[Kyle S. Budd Jr.]

It was a proposal for the 2011 code.

Thanks again

Kyle

 

[Pierre C Belarge]

The code making panel does not agree. See the panel comment on the proposal that is posted in the other forum.

I remember the first time I learned of tapping from a breaker lug/terminal. I had a hard time wrapping my brain around the concept, because I had learned that conductors had to be properly sized based on the breaker size.