Clear taps.

[mxslick]

K2X, that is some great looking work!! Big thumbs up. :grin:

 

[buck33k]

I don't think so. A set of conductors or each set of conductors is allowed to be connected to the transformer secondary without OCP as specified in the following sub-sections 240.21(C). Not connected to a wire 5 feet away from the secondary, but 'to the secondary'.

And then there is the fact that you cannot supply a tap through a tap 240.21.

I assumed there was no overcurrent protection ahead of the taps. If so, this is allowed because these are secondaries from a utility transformer?

 

[augie47]

Taps won't have an AIC rating, but they will have a Short Circuit Current Rating (SCCR) and this rating must be equal to or greater than the available short circuit current at the point where they are installed. There are connections with high SCCR ratings available.

There are accepted tables that show the withstand of conductors based on the fault current and the clearing time of the OCPD.

Don, Your knowledge in this area far surpasses mine so allow me to ask a couple of dumb questions.
The replies I am receiving from Ilsco and Burndy are stating their insulated taps do not have a SCCR rating (Burndy states theirs do have a dielectric rating).
In a properly designed system should it not be required that such connectors have a rating as high as the system AIC ?
If they are not rated, should the be considered to have a mini mun rating such as 5k or 10k?

In regard to the power distribution blocks, they all seem to state that the meet UL standard QPQS which list the blocks only for load side service installations. With that in mind, it would seem that they could not properly be used on service (line) taps. Comment ?

I don't wish to cut the limb on which I am sitting as I have seen (and used) insulated taps and PF blocks on services for quite a while. It appears that such installations don't meet Code. Am I mistaken ?

 

[ryan_618]

According to the UL White Book:

Power distribution blocks are considered suitable for use on circuits having available fault current not greater than 10,000 rms symmetrical amps,
unless marked with a larger value. Power distribution blocks are marked
??Short-Circuit Current Rating?? together with the value of the rating and the
maximum voltage. A power distribution block may additionally be marked
to identify an overcurrent protective device (fuse or circuit breaker) to be
used ahead of the power distribution block.

...Seems sort of low to me.

 

[don_resqcapt19]

Gus,
As far as I know all of the parts of the system, including any type of connections and splices must comply with 110.10. As I see it, any connector that does not have a short circuit rating cannot be used in any NEC application.
If the power distribution blocks are listed to a standard that only applies to load side installations, then the use of those blocks on the line side of the service disconnect would be a 110.3(B) violation. That being said, I would not see a problem using the distribution block on the line side of the service OCPD, as long as the block had a SCCR rating equal to or greater than the available current at that point in the circuit.