Tapping transformer secondary conductors

[philly]

I'm looking at a set of 480V transformer secondary conductors (8 Sets of 500 MCM)that feed the normal side of an ATS (Generator feeds emergency side) with the load side of the ATS feeding into a 3000A SWBD with a 3000A Main.

The load side of the ATS is also "tapped" with a second set of feeder cables that feed another Switchboard at another location.

I always thought that you cannot "tap" transformer secondary conductors but perhaps there is a provision in 240.21 that allows this situation? ATS, Transformer and Bus are located side by side in very close proximity.

Is the secondary tap at this ATS permissible in this instance?

 

[philly]

I forgot to mention that these secondary transformers may be service entrance conductors. Customer owns the transformer but I'm trying to determine where the service entrance demarcation is.

 

[iwire]

Does the ATS include overcurrent protection within it or immediately adjacent to it?

 

[petersonra]

maybe it is not really a tap. a tap by definition means that the conductor ampacity is not protected by the upstream OCPD.

do service conductors ever really have taps?

 

[iwire]

do service conductors ever really have taps?

As you suspect no, if you splice onto a service conductor you have created another service conductor.

 

[philly]

Does the ATS include overcurrent protection within it or immediately adjacent to it?

No ATS does not have internal OCPD's.

 

[augie47]

No ATS does not have internal OCPD's.

Continue your quest to determine where the service point is located. If the conductors to the ATS are deemed "Service", you must have OCP integral with or ahead of the ATS.
Depending on the details the same may be true if they are simply non-service transformer seciondry conductors dependon on 240.21(C) rules and 225.36 rules.

 

[iwire]

Continue your quest to determine where the service point is located. If the conductors to the ATS are deemed "Service", you must have OCP integral with or ahead of the ATS.
Depending on the details the same may be true if they are simply non-service transformer seciondry conductors dependon on 240.21(C) rules and 225.36 rules.

I agree.

 

[philly]

Continue your quest to determine where the service point is located. If the conductors to the ATS are deemed "Service", you must have OCP integral with or ahead of the ATS.
Depending on the details the same may be true if they are simply non-service transformer seciondry conductors dependon on 240.21(C) rules and 225.36 rules.

I'm trying to determine weather or not the transformer secondary feeders are considered service entrance. Transformer is customer owned and fed from overhead lines on customer property but not sure where metering or service point is located.

If transformer secondary conductors are service entrance then I agree its a no brainer that the ATS has to be a service rated ATS with integral breakers.

If this is not considered a service wont the ATS still need to have internal OCPD in order to meet ATS withstand ratings. ATS's have a 3-cycle rating and you can get them with a 30-cycle rating however with no OCPD on the transformer secondary I don't believe the primary device would clear a fault in 30 cycles? Is there a longer rated ATS that can relay on the slow clearing time of the transformer primary device or must an OCPD on the secondary side be used that clears in 30 cycles or faster?

If these are not service entrance conductors then I think 240.21(C)(4) would apply since equipment is located outdoors? In this case can the ATS still be installed without any upstream OCPD?

 

[Smart $]

...
If these are not service entrance conductors then I think 240.21(C)(4) would apply since equipment is located outdoors? In this case can the ATS still be installed without any upstream OCPD?

Just because the equipment is outside does not mean (C)(4) must be used.

Does the secondary configuration meet the requirements of (C)(1) for example?