Taps with same parallel set quantity in tap & feeder

[Carultch]

Suppose you have 3 parallel sets in a feeder, and you plan on tapping a circuit that also has 3 sets in parallel. Provided that you preserve the symmetry as much as practical, is it code compliant to make individual wire taps, as an alternative to a complete 9-terminal device that would join all of them together?

This question would also apply if there is any common factor between the sets you are joining. Obviously tapping 2-sets onto 3-sets requires an 8-terminal block to join them all together (3 in, 3 out, 2 tap), because 2 and 3 are both prime. But because 2 and 6 have the factor of 2 in common, if you plan to tap 2 sets onto 6 sets, would have this question apply, in order to connect each tap set onto a group of 3 sets from the feeder.

 

[petersonra]

The code requires that each set of parallel conductors be connected at each end. What you are proposing to do does not do that. Having said that some cases you might be able to run one wire straight through the connector so there would only be 6 connections instead of 9. I've done this a few times where I had connectors close to each other. Instructions don't say you can't do this.

 

[Smart $]

Where you have the same number of main conductors as taps, if you use something like a gutter tap, where you do not cut the main to make the tap, you technically maintain the integrity of the parallel conductors by definition. It is only when you cut the main to make the tap are you obligated to connect all the ends together.

 

[wwhitney]

Where you have the same number of main conductors as taps, if you use something like a gutter tap, where you do not cut the main to make the tap, you technically maintain the integrity of the parallel conductors by definition. It is only when you cut the main to make the tap are you obligated to connect all the ends together.

Under this interpretation, what part of 310.10(H) would require the gutter taps to be located at the same point (distance from the end) along each conductor of the parallel set?

It seems to me an argument can be made that the arrangement proposed in the OP would still cause the conductors to be "electrically connected" at both ends and that they need not be physically connected at both ends. Not sure what I think.

Here's a somewhat simpler scenario related to the OP's question: suppose in a parallel set each conductor is upsized for voltage drop, but the size is larger than the lugs at one end can accommodate. Can each conductor in the parallel set be individually spliced to a smaller conductor (of identical lengths) to land on the equipment lugs, or must the parallel set be interconnected when downsizing? Is there a difference between using a pin adapter versus a splice to a short length of smaller conductor?

Cheers, Wayne

 

[Smart $]

Under this interpretation, what part of 310.10(H) would require the gutter taps to be located at the same point (distance from the end) along each conductor of the parallel set?

If you are going to make me guess, I'll go with (1). If you understand the reasoning for the stated conditions, you'll agree. What's the alternative, you tap at a relatively significant distance and provide the AHJ the prerogative to flag for correction.

It seems to me an argument can be made that the arrangement proposed in the OP would still cause the conductors to be "electrically connected" at both ends and that they need not be physically connected at both ends. Not sure what I think.

Let's us know if you resolve the issue. :happyyes:

Here's a somewhat simpler scenario related to the OP's question: suppose in a parallel set each conductor is upsized for voltage drop, but the size is larger than the lugs at one end can accommodate. Can each conductor in the parallel set be individually spliced to a smaller conductor (of identical lengths) to land on the equipment lugs, or must the parallel set be interconnected when downsizing? Is there a difference between using a pin adapter versus a splice to a short length of smaller conductor?

It all comes down to what you consider an end is that qualifies for the 310.10(H) requirement the parallel conductors be "electrically joined at both ends".

 

[Carultch]

Where you have the same number of main conductors as taps, if you use something like a gutter tap, where you do not cut the main to make the tap, you technically maintain the integrity of the parallel conductors by definition. It is only when you cut the main to make the tap are you obligated to connect all the ends together.

So what you are telling me, is that if your tap method doesn't technically terminate the feeder conductor, but rather maintains its factory continuity and just adds another connected circuit in the middle of it, it is OK to do individual conductor-to-conductor taps. An example would be the gutter tap like you suggest, or an insulation piercing connector. Am I understanding correctly?

 

[Smart $]

So what you are telling me, is that if your tap method doesn't technically terminate the feeder conductor, but rather maintains its factory continuity and just adds another connected circuit in the middle of it, it is OK to do individual conductor-to-conductor taps. An example would be the gutter tap like you suggest, or an insulation piercing connector. Am I understanding correctly?

That's the way I see it. YMMV

 

[petersonra]

some people have suggested a parallel feeder situation cannot have any splices because that would mean an end to one conductor and the start of another which is not permitted by the parallel conductor rules.

lets look at what the allowance for conductors in parallel actual says.

310.10 (H) Conductors in Parallel.
(1) General. Aluminum, copper-clad aluminum, or copper
conductors, for each phase, polarity, neutral, or grounded circuit
shall be permitted to be connected in parallel (electrically
joined at both ends) only in sizes 1/0 AWG and larger where
installed in accordance with 310.10(H)(2) through (H)(6).

It seems pretty clear that the parallel conductors have to be joined together at the ends of the runs. There does not appear to be any wiggle room here. there is no provision for the parallel connection being anywhere other than the ends of the parallel conductors.

 

[Smart $]

... There does not appear to be any wiggle room here. there is no provision for the parallel connection being anywhere other than the ends of the parallel conductors.

Okay... but you are saying nothing different than what we can read.

Let me put it like this. Where 310.10(H)(1) states "electrically joined at both ends" it means source end and load end. In between, we must comply with 310.10(H)(2).

 

[jaggedben]

Suppose you have 3 parallel sets in a feeder, and you plan on tapping a circuit that also has 3 sets in parallel. Provided that you preserve the symmetry as much as practical, is it code compliant to make individual wire taps, as an alternative to a complete 9-terminal device that would join all of them together?

This question would also apply if there is any common factor between the sets you are joining. Obviously tapping 2-sets onto 3-sets requires an 8-terminal block to join them all together (3 in, 3 out, 2 tap), because 2 and 3 are both prime. But because 2 and 6 have the factor of 2 in common, if you plan to tap 2 sets onto 6 sets, would have this question apply, in order to connect each tap set onto a group of 3 sets from the feeder.

I don't see a safety issue with what you're proposing. As far as can tell, what you propose addresses the safety issue that the code requirement was put in there to address. As you well know, tapping only some of the sets can lead to problems, but as long as you tap them all I don't see how it does. However, if you want to be on the conservative side of code interpretation, I'd say block all the sets together where they are tapped, regardless of whether the connector requires cutting the main run. I think that splitting hairs over whether the tapped conductors are cut or not is ... silly. It makes no difference electrically. The question is whether you are required to put them all into one node or not. One could argue that the code says you do.

Just my opinion.