Difference between a splice and tap - feeder

[ttjangu]

First post here so go easy on me. I work for an electrician and we do mostly residential rewire type stuff. There have been a few times when we have added subpanels by just tee splicing (polaris connectors) into the feeder cable in an approved box. Both times the splice has only been protected by the main panel breaker (sized appropriately for the feeder) and the ampacity of the wire has remained the same. For some reason this seems weird to me but the guy I work for says it is fine but not the best way to do it / sometimes unavoidable. My question is, Is this considered a tap which tap rules would apply to or is it okay to tee splice into a feeder so long as load considerations are okay. Does each subpanel require it's own breaker or does it matter since the main breaker is protecting it and the wire is not different sizes before or after the splice/tap? I am getting hung up on the tap rule versus the defintion of a splice. Based on the definition of a tap, does using the same wire on all three sides of the tee make it okay so long as the wire does not exceed the protection in front of it?

An example of the above, the last one we did.

Small apartment building where we added a subpanel in the garage to one of the units. The main breaker was a 60 amp breaker off a meter stack which feeds a sub in the apartment via 6/3 copper. No space on the meter stack for additional breakers since it is only a main disconnect for each units sub panel. Rather than open walls in multiple apartments to get to that particular units subpanel, we just tee spliced the 6/3 under the building with 3 way polaris connectors in a 6x6x4 box and ran 6/3 to another subpanel that only had a few circuits on it.


Section 240 definition of a tap

. 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

 

[Smart $]

What you are describing appears to be a splice, not a tap. Assuming you are running 6/3 NM (copper), the max load for both subpanels combined is 55A, assuming no derating.

 

[ttjangu]

What you are describing appears to be a splice, not a tap. Assuming you are running 6/3 NM (copper), the max load for both subpanels combined is 55A, assuming no derating.

Thanks. Okay, Still seems weird. So to take it to the extreme, could each wire of 6/3 be spliced with 8 way polaris connectors (6/3 on each) to feed 8 separate 50 amp panels if the main run off the "splice" was protected by one 50 amp breaker which also serves as main disconnect? I know load calcs are a different issue that play into this. Only wondering about the correctness of the wiring itself.

 

[Dennis Alwon]

Art. 240 talks about taps

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.

 

[Smart $]

Thanks. Okay, Still seems weird. So to take it to the extreme, could each wire of 6/3 be spliced with 8 way polaris connectors (6/3 on each) to feed 8 separate 50 amp panels if the main run off the "splice" was protected by one 50 amp breaker which also serves as main disconnect? I know load calcs are a different issue that play into this. Only wondering about the correctness of the wiring itself.

The NEC places no limit on the number of splices. As you have already noted, the limiting factor is the calculated load.

 

[ttjangu]

The NEC places no limit on the number of splices. As you have already noted, the limiting factor is the calculated load.

Wow, thanks. I thought my boss was taking a shortcut. How often does this actually happen or do others here do this much? After a bit more thought, I suspect this might be done more in commercial applications than what is typically seen is residential but we don't do much commercial so....

 

[Smart $]

Wow, thanks. I thought my boss was taking a shortcut. How often does this actually happen or do others here do this much? After a bit more thought, I suspect this might be done more in commercial applications than what is typically seen is residential but we don't do much commercial so....

I've done very little residential, but a bevy of commercial and industrial. Can't say I've ever done anything close to resembling what you describe.

 

[ttjangu]

I've done very little residential, but a bevy of commercial and industrial. Can't say I've ever done anything close to resembling what you describe.

Ha, so now I am questioning it again if you have not seen it before. Even a tee splice, not the eight way extreme example?

 

[Smart $]

Ha, so now I am questioning it again if you have not seen it before. Even a tee splice, not the eight way extreme example?

Didn't say I've not seen it... just that I've never done it myself. In what I have seen, splicing into over 20A circuits is not done all that often.

 

[kwired]

First post here so go easy on me. I work for an electrician and we do mostly residential rewire type stuff. There have been a few times when we have added subpanels by just tee splicing (polaris connectors) into the feeder cable in an approved box. Both times the splice has only been protected by the main panel breaker (sized appropriately for the feeder) and the ampacity of the wire has remained the same. For some reason this seems weird to me but the guy I work for says it is fine but not the best way to do it / sometimes unavoidable. My question is, Is this considered a tap which tap rules would apply to or is it okay to tee splice into a feeder so long as load considerations are okay. Does each subpanel require it's own breaker or does it matter since the main breaker is protecting it and the wire is not different sizes before or after the splice/tap? I am getting hung up on the tap rule versus the defintion of a splice. Based on the definition of a tap, does using the same wire on all three sides of the tee make it okay so long as the wire does not exceed the protection in front of it?

An example of the above, the last one we did.

Small apartment building where we added a subpanel in the garage to one of the units. The main breaker was a 60 amp breaker off a meter stack which feeds a sub in the apartment via 6/3 copper. No space on the meter stack for additional breakers since it is only a main disconnect for each units sub panel. Rather than open walls in multiple apartments to get to that particular units subpanel, we just tee spliced the 6/3 under the building with 3 way polaris connectors in a 6x6x4 box and ran 6/3 to another subpanel that only had a few circuits on it.


Section 240 definition of a tap

. 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

The reason NEC has a definition for that word is when they use that word they have a more narrow definition of what it applies to in the context of NEC usage then a dictionary may have.

A three way junction (not just limiting the discussion to electrical conductors) may be three separate elements joined at one point, or it may be a main run that never gets physically cut yet another branch is somehow taken from that junction.

To NEC a tap conductor is when a branch from that main element is no longer protected at or below it's ampacity regardless of what method is used to make the connection.