TAP CONDUCTOR VIOLATION.

[VENgineer]

Good afternoon, I hope you can help me with this situation.

Yesterday, I conducted an inspection in a 2-story commercial building and encountered the following.

Main Disconnect 1200Amps. 4 sets of 350MCM CU are entering. 3 sets of 350MCM CU are exiting (First violation since the ampacity is below the OCPD) as it is still considered a feeder and not a tap conductor.

Then, and even more surprising, each of the conductors goes to a different polaris tap, not as parallel conductors to the same polaris tap. I see this as a clear violation of 240.21, Tap of Tap.

I will make a diagram to help you understand better, and please confirm if I am correct or if I am missing something.

 

[infinity]

From your diagram they are indeed tapping a tap. They need to rip it out and start over.

 

[VENgineer]

This installation is over 40 years old. I work in Florida, and according to the new law, buildings need to be recertified every 40 or 30 years. Yesterday, I was recertifying this building and found this situation.

 

[infinity]

Funny from the photos that equipment doesn't appear to be 40 years old.

 

[jaggedben]

What infinity said. Also the wireway looks too small to me.

 

[VENgineer]

"Actual Installation"

 

[petersonra]

Good afternoon, I hope you can help me with this situation.

Yesterday, I conducted an inspection in a 2-story commercial building and encountered the following.

Main Disconnect 1200Amps. 4 sets of 350MCM CU are entering. 3 sets of 350MCM CU are exiting (First violation since the ampacity is below the OCPD) as it is still considered a feeder and not a tap conductor.

I would call it a violation of the parallel conductor rule since they are not in parallel, therefore it is not a "tap" conductor.

Then, and even more surprising, each of the conductors goes to a different polaris tap, not as parallel conductors to the same polaris tap. I see this as a clear violation of 240.21, Tap of Tap.

I will make a diagram to help you understand better, and please confirm if I am correct or if I am missing something.

This would be fairly easy to fix. Three sets of fuses or three MCCB (the next size up would be 350 A).

 

[VENgineer]

REQUIRED INSTALLATION

 

[jaggedben]

I would call it a violation of the parallel conductor rule since they are not in parallel, therefore it is not a "tap" conductor.

I don't see any parallel conductors. I see three separate taps from the main disconnect.

This would be fairly easy to fix. Three sets of fuses or three MCCB (the next size up would be 350 A).

I guess if you think replacing the 1200A service disconnect is the easiest fix.

View attachment 2571673 REQUIRED INSTALLATION

I believe you'd need a fourth 350MCM for the main feeder to not be a tap, unless the 1200A disco can have a lower OCPD rating. You also need more taps than three; one tap of all conductors for each meter/disconnect being fed, and they each have to tap all feeder conductors (as you've shown.)

ALTERNATIVELY, separate taps could be run from the main disconnect to each meter/disconnect, without a main feeder.

I'll leave it to others to comment on the comparative feasibility and cost of those options.

 

[petersonra]

The three mccbs would go in line with the three sets of 350 MCM conductors. Nothing else changes.

 

[kwired]

I don't see any parallel conductors. I see three separate taps from the main disconnect.

I guess if you think replacing the 1200A service disconnect is the easiest fix.


I believe you'd need a fourth 350MCM for the main feeder to not be a tap, unless the 1200A disco can have a lower OCPD rating. You also need more taps than three; one tap of all conductors for each meter/disconnect being fed, and they each have to tap all feeder conductors (as you've shown.)

ALTERNATIVELY, separate taps could be run from the main disconnect to each meter/disconnect, without a main feeder.

I'll leave it to others to comment on the comparative feasibility and cost of those options.

It would not be a tap if each all four are joined together at both ends to create a conductor with an ampacity of 1240.

If they had done this then it would be legal to make taps from that to each disconnect.

Otherwise the OP is correct, the installation essentially has taps from tap conductors as it is. All the tap rules require taps to end at overcurrent protection. 10 foot rule doesn't necessarily require it to end at an individual OCPD but certainly doesn't allow it to end with another tap conductor(s).

 

[jaggedben]

It would not be a tap if each all four are joined together at both ends to create a conductor with an ampacity of 1240.

...

(Is that different from what I said? I don't think so.)

 

[kwired]

(Is that different from what I said? I don't think so.)

You missed mentioning they need tied together on both ends for it to not be considered tap conductors though that may been what you were thinking?

 

[jaggedben]

You missed mentioning they need tied together on both ends for it to not be considered tap conductors though that may been what you were thinking?

Yes, and I was responding to the OP's drawing where he already showed that.

 

[topgone]

Q:
Don't we need to know the length of the tap and the protection rating of the overcurrent protection that the tap conductors land on so we can be sure whether it is a violation of the tap rules?

 

[kwired]

Q:
Don't we need to know the length of the tap and the protection rating of the overcurrent protection that the tap conductors land on so we can be sure whether it is a violation of the tap rules?

In OP they tap the 1200 amp OCPD with 350, then tap the 350 with non specified but presumably smaller conductors. That is a violation even if you don't know what size the second conductor or final OCPD is. NEC doesn't straight out say it, but you can't "tap a (feeder) tap" in any situation.

 

[Jpflex]

This installation is over 40 years old. I work in Florida, and according to the new law, buildings need to be recertified every 40 or 30 years. Yesterday, I was recertifying this building and found this situation.

Does this mean that old installations that were once legal may not be grandfathered in?

What do you do if you have knob and tube where you can’t find suitable replacement equipment? Do you rip out entire runs?

 

[CoolWill]

Funny from the photos that equipment doesn't appear to be 40 years old.

That Sylvania main breaker tells me it's pretty close.

 

[jaggedben]

That Sylvania main breaker tells me it's pretty close.

Was Greaves making 5 port insulated multi-tap connectors 40 years ago? Consider me skeptical. I suspect that much of the equipment - especially the main and the wireway - is original, but that the wiring was redone at some point, probably when some number of the load side disconnects were added.

 

[CoolWill]

Was Greaves making 5 port insulated multi-tap connectors 40 years ago? Consider me skeptical. I suspect that much of the equipment - especially the main and the wireway - is original, but that the wiring was redone at some point, probably when some number of the load side disconnects were added.

I have no idea when those were introduced. I don't remember seeing them before 2003 or 2004 or so. But that service is old. When it was altered is anybody's guess.