SCCR Rating-Service Taps

[augie47]

Recent threads here cause me to have concern about the SCCR rating of the insulated taps I see often in Service Tap situations.
In discussions with ILSCO and BURNDY I find their insulated taps have no SCCR rating.
A Burndy representative gave the following reply to one of my questions:
I?ve been told service taps on line side connections do not need a short circuit rating so Unitap, split bolts or any other type of UL Listed connector can be used. However, load side connections do need a Short Circuit Rating so a BDB Power Distribution Block will need to be used.
From earlier threads that seems incorrect but we are in an area where I lack knowledge.
Input ?

 

[benaround]

Gus,

My thinking is that if the tap is under NEC guidelines, then the equipment must be rated

for the availible fault current that it may have to carry, weather it be line or load. jmo.

 

[augie47]

Interesting and confusing since both ILSCO and BURNDY advise their insulated taps have no SCCR ratings.
I hate being stupid.

 

[benaround]

It looks like Bussmann has them as well as sccr PDB . It does seem odd that those companies

don't have sccr taps. Personally I can't recall even looking for a sccr for an insulated tap.

IMO, this is something that can be overlooked very easily by all that are involved.

 

[augie47]

I appreciate the input other have provided on this subject both in this thread and others.
I have had numerous conversations on this and my analysis is certainly subject to be incorrect, but this is the summary of the input I have received:

Since the question 1st arose concerning SCCR ratings on Insulated Taps and Power Distribution Blocks, I have had contact with ILSCO, BURNDY & U.L. and conversations with numerous inspectors.

I may not have this correctly, and if you see error in my information, please let me know.


The question originally arose concerning the use of insulated taps and PDB as a means to tap service conductors.

It appears that Insulated Taps do not carry a SCCR rating as their UL listing, ZMVV, does not require them to do so.
They will have a product temp rating, and Dielectric integrity of insulation.
Power Distribution Blocks, on the other hand, do have an SCCR rating and are listed under UL QPQS. Unless marked otherwise, that rating is 10k.
In addition, PDBs are listed for use on the load side of service equipment.

It appears the reason one carries a SCCR and the other does not is that PDB are often a component of assemblies which require a SCCR rating.

In summary, although some inspectors have expressed a need for an insulated tap to have a SCCR rating, by their listing, such is not required.
In addition PDBs are not listed for Line side of Service use and it should also be noted they do have a SCCR rating if they are encountered on load side installations.

 

[benaround]

Gus,

Well thanks for passing that on, seems to me you know quite abit about this subject.

This Forum and its Members have really opened my eyes in many areas.

 

[don_resqcapt19]

Gus,
I don't see how the listing of the insulated tap changes anything. If the tap does not have a SCCR rating, how can you know that your installation is in compliance with 110.10?

 

[augie47]

Gus,
I don't see how the listing of the insulated tap changes anything. If the tap does not have a SCCR rating, how can you know that your installation is in compliance with 110.10?

Don, your question has troubled me since the beginning of this "Don Quixote" quest. In fact, that was the reason I spent a ton of time on it in recent days and I have no answer.
As an inspector, I would like to have assurance that all components meet required criteria, but I know of nothing else we as inspectors can do here.
Do you ?
After e-mails with 3 manufacturers and UL, it seems the insulated taps are listed as connectors, the same as a lug or split bolt. The latter have been used for eons on service taps and connections without question.
It's a listed product, without any SCCR rating or limitation, and I don't see how I can evaluate it any more than I would a split bolt, two-bolt connector or a lug in the same system.
I'm open to your suggestion as to any other route to take.

 

[cschmid]

okay lets throw a twist in here the SCCR starts at the power companies transformer so every thing from the transformer to the breakers would have to be rated. that is where arc flash starts correct otherwise you could pick any SCCR you wanted if the poco did not label transformer..

 

[benaround]

okay lets throw a twist in here the SCCR starts at the power companies transformer so every thing from the transformer to the breakers would have to be rated. that is where arc flash starts correct otherwise you could pick any SCCR you wanted if the poco did not label transformer..

If the service and feeders are installed per NEC, if a down stream fault occurs, the feeder

breaker or the main breaker will trip and the components up stream of the breakers will not

have to endure the stresses involved, could this be correct ?

 

[cschmid]

That is how it is rated. Now you add a physical connection before the breaker and it now has the ability becomes the weak link. So how does the rating apply if the wire makes it does the splice have to be rated as well? I think so but we are now in grey area.

 

[don_resqcapt19]

Gus,
I have no idea on how to apply the rule to these items, but it appears to me that they are required to have a SCCR and maybe the best method would be for all of the inspectors to prohibit the use of these items until the manufacturers have them tested and marked with a SCCR:grin:

I understand that they have been used for years without question, and I am not aware of failures because of high short circuit currents, but I think that they need to be tested and marked, but this is not likely to happen so I guess we just keep doing what we have been doing.