Transformer secondary taps

[Pierre C Belarge]

Before and after you make the splice you have two conductors. If the first conductor (supply end) is not protected at its ampacity it is a tap conductor. If you connect the second (load end) conductor to the first without overcurrent protection, it is also a tap conductor and you are not permitted to tap a tap.

Don
This is your opinion and I do not agree.

If I take a conductor and splice another conductor to it the same size, all I have done is extend the conductor to a different length.


If I have a 4 AWG conductor that is 4 feet long, and I splice on another 4 foot length of 4 AWG conductor to it, in essence I have an 8 ft length of 4 AWG conductor.

 

[RB1]

The rule says "no conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor conductor except through an overcurrent device meeting the requirements of 240.4". A "tee" connection would not be permitted under this rule. A splice in a single conductor would be permitted. Thats the way I see it. An individual circuit path from source to load is a single conductor regardless of how many splices there are. Tee on the other hand are a different story.

 

[mpd]

I agree with don, you cannot tap a tap, why would you need a splice on a 10ft or 25ft tap conductor?

 

[iwire]

If I take a conductor and splice another conductor to it the same size, all I have done is extend the conductor to a different length.

If I do that with a 14 AWG in a device box how many conductors do I have for box fill? :smile:

I really don't know where I stand on this whole thing.

I wish I knew what the safety issue would be about supplying 6 over current devices from one set of conductors totaling less the ampacity of the conductors would be?

 

[don_resqcapt19]

Don
This is your opinion and I do not agree.

If I take a conductor and splice another conductor to it the same size, all I have done is extend the conductor to a different length.


If I have a 4 AWG conductor that is 4 feet long, and I splice on another 4 foot length of 4 AWG conductor to it, in essence I have an 8 ft length of 4 AWG conductor.

Pierre,
This is just a quirk in the code wording. You have two condutors and adding a splice does not make it one conductor. If the first conductor was a "tap" conductor, then splicing the second onto the first results in a code violation. Is there any type of hazard created? No. Is this the intent of the code rules? Probably not. Is this what the code words say? Yes.

 

[Pierre C Belarge]

First off let me make it clear that I understand the principle of tapping off of a tap conductor... and that the NEC does not permit tapping a tap conductor. I have no issue with that.


What I am saying is in regards to tap conductors as per 240.21(C) in relation with the definition of tap Conductor in 240.2.

Splicing 2 pieces of the same size conductor together is not tapping a tap.

Splicing a smaller size conductor from a larger size conductor, such as splicing an 8 AWG onto/from a 4 AWG conductor would be considered a tap.

 

[sandsnow]

Before and after you make the splice you have two conductors. If the first conductor (supply end) is not protected at its ampacity it is a tap conductor. If you connect the second (load end) conductor to the first without overcurrent protection, it is also a tap conductor and you are not permitted to tap a tap.

I'm on board with you there.

Wasn't there something about transformers in the OP???

 

[sandsnow]

If I take a 3/0 tap from a 600 kcmil conductor and its 8 feet long. I find that it is a little short to reach the line side of the fusible switch. I think it is perfectly acceptable to extend that with another piece of 3/0 to reach the lug. As long as I don't overfill the width of the wiring gutter.

 

[Pierre C Belarge]

Is the splice that is being discussed here resulting in 2 tails or is the splice 'in-line' resulting in 1 conductor?

 

[don_resqcapt19]

First off let me make it clear that I understand the principle of tapping off of a tap conductor... and that the NEC does not permit tapping a tap conductor. I have no issue with that.


What I am saying is in regards to tap conductors as per 240.21(C) in relation with the definition of tap Conductor in 240.2.

Splicing 2 pieces of the same size conductor together is not tapping a tap.

Splicing a smaller size conductor from a larger size conductor, such as splicing an 8 AWG onto/from a 4 AWG conductor would be considered a tap.

Please show me the words in the definition of a "tap" that say anything about the relative sizes of the conductors involved.

 

[don_resqcapt19]

Is the splice that is being discussed here resulting in 2 tails or is the splice 'in-line' resulting in 1 conductor?

Using the code language, it doesn't make any difference.

 

[Pierre C Belarge]

Please show me the words in the definition of a "tap" that say anything about the relative sizes of the conductors involved.

Tap Conductors.
...that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that protected as described elsewhere in 240.4.


This is "inferring" the size of the conductor.

 

[don_resqcapt19]

Tap Conductors.
...that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that protected as described elsewhere in 240.4.

This is "inferring" the size of the conductor.

No...it is just saying that the conductor does not have overcurrent protection eqaul to or less than the ampacity of the conductor. If I connect a #2 to the transformer and then connect a 500kcmil to the #2, the 500 is still a tap conductor just like if I would connect a #4 or even another #2. The size is not the issue in making a "tap conductor". The only issue is the overcurrent protection, or more correctly the lack thereof.

 

[jim dungar]

I'm on board with you there.

Wasn't there something about transformers in the OP???

This quirk in the NEC language only occurs on transformer secondaries where all secondary connections are considered taps (i.e. 240.21(C)2 or greater). For all other situations a same size, or larger, spliced conductor is protected by the upstream OCPD.

 

[sandsnow]

This quirk in the NEC language only occurs on transformer secondaries where all secondary connections are considered taps (i.e. 240.21(C)2 or greater). For all other situations a same size, or larger, spliced conductor is protected by the upstream OCPD.

I don't see the word tap in 240.21(C) anywhere. As in my previous post they are not tap conductors. They are secondary conductors. There is no OCP on there supply side of any rating equal to the ampacity of the conductor or not.

 

[Smart $]

This quirk in the NEC language only occurs on transformer secondaries where all secondary connections are considered taps (i.e. 240.21(C)2 or greater). For all other situations a same size, or larger, spliced conductor is protected by the upstream OCPD.

I don't agree that transformer secondary conductors are taps (at least not all of them).

Where does the code explicitly say that? Carefully read 240.21(C). The only place the word "tap" is mentioned is regarding a feeder tap for the primary.

If a xfmr's secondary is protected by the primary's ocpd, and the secondary conductors are sized to carry the xfmr's rated power, I do not see where they are not protected ahead of the the supply.

I believe you mean to say this when you mention 240.21(C)(2) and greater.

But at the same time 240.21(C)(2) and greater does not mention the word "tap" regarding these conductors.

 

[iwire]

If a xfmr's secondary is protected by the primary's ocpd, .

But in many cases the primary's OCPD does not protect the secondaries. (C)(1) last paragraph.

 

[don_resqcapt19]

The secondary conductors of all transformers except two wire to two wire and three wire to three wire delta/delta transformers are taps and in some cases even the secondary conductors of these types are taps.

 

[iwire]

The secondary conductors of all transformers except two wire to two wire and three wire to three wire delta/delta transformers are taps and in some cases even the secondary conductors of these types are taps.

Don, I am still learning on this subject so this is a real question. :smile:

How did you determine that?

 

[Pierre C Belarge]

The secondary conductors of all transformers except two wire to two wire and three wire to three wire delta/delta transformers are taps and in some cases even the secondary conductors of these types are taps.

I have been taught exactly the same principle as what you have stated in this post.