Raceways for 10' Feeder Taps Entirely within an Industrial Control Panel

[omnisciendus]

In a main control panel (Type 12 enclosure) of industrial machinery, I would like to run wires from the panel main disconnect to a power distribution block, then connect feeder tap conductors from the block to overcurrent protective devices inside same panel, which are (much) shorter than 10 feet. In the 2023 NEC feeder tap rules, 240.21 (B)(1)(3) says that these feeder tap conductors need to be enclosed in a raceway "except at the point of connection." Does this mean I would have to mount a raceway inside the control panel? Does the control panel itself count as the "point of connection?"

These panels are installed in jurisdictions where the NEC is law, and where NFPA 79 and UL 508A are referenced, but not explicitly required. That said, the equivalent rule in NFPA 79, 7.2.8 (1) (C), just requires "the conductor is suitably protected from physical damage" (and also that it doesn't leave the enclosure).

 

[jim dungar]

Are your panels Listed, as many AHJ's require?

 

[don_resqcapt19]

It is my opinion that 240.21(B)(1)(2) and not 240.21(B)(1)(3) applies. 240.21(B)(1)(3) applies where the tap conductors leave the enclosure where the tap is made. I have never seen a raceway in a control panel for tap conductors.

 

[omnisciendus]

Are your panels Listed, as many AHJ's require?

They are UL listed when it's required, but as far as I can tell the 508A requirement for feeder taps, 32.4.2 (B), is more lenient than the NEC requirement anyway. Similar to NFPA 79, it just says "the tap conductors do not extend beyond the industrial control panel."

It is my opinion that 240.21(B)(1)(2) and not 240.21(B)(1)(3) applies. 240.21(B)(1)(3) applies where the tap conductors leave the enclosure where the tap is made. I have never seen a raceway in a control panel for tap conductors.

Don't both sections apply? 240.21 (B)(1) says "the tap conductors comply with all of the following." I haven't ever seen raceways in ICPs either, and it makes sense to me that the tap conductors should be adequately protected inside a rated enclosure, but I'm having trouble seeing how the code agrees with that.

 

[don_resqcapt19]

They are UL listed when it's required, but as far as I can tell the 508A requirement for feeder taps, 32.4.2 (B), is more lenient than the NEC requirement anyway. Similar to NFPA 79, it just says "the tap conductors do not extend beyond the industrial control panel."

Don't both sections apply? 240.21 (B)(1) says "the tap conductors comply with all of the following." I haven't ever seen raceways in ICPs either, and it makes sense to me that the tap conductors should be adequately protected inside a rated enclosure, but I'm having trouble seeing how the code agrees with that.

The wording in (3) says to me that it only applies where the taps leave the original enclosure.

 

[jim dungar]

They are UL listed when it's required, but as far as I can tell the 508A requirement for feeder taps, 32.4.2 (B), is more lenient than the NEC requirement anyway. Similar to NFPA 79, it just says "the tap conductors do not extend beyond the industrial control panel."

Yes those rules are more lenient. The NEC is very conservative because it has no control over the skill or expertise of the person implementing it.

The NEC allows Listed equipment to be used 'as is', without compliance to NEC requirements because it trusts the listing process to have controls over the actual wiring.

So follow the limitations of the NEC or always have your panels Listed.

 

[omnisciendus]

Don, that makes sense to me, and I'll talk it over with our inspector. Thanks!

Yes those rules are more lenient. The NEC is very conservative because it has no control over the skill or expertise of the person implementing it.

The NEC allows Listed equipment to be used 'as is', without compliance to NEC requirements because it trusts the listing process to have controls over the actual wiring.

So follow the limitations of the NEC or always have your panels Listed.

According to NEC 90.7, since UL 508A is included in Annex A, it's considered compatible with the NEC. Thus the internal wiring doesn't need to be inspected for installation under the NEC (read: doesn't actually need to meet NEC rules, just UL 508A rules). Is that right?

 

[jim dungar]

Don, that makes sense to me, and I'll talk it over with our inspector. Thanks!


According to NEC 90.7, since UL 508A is included in Annex A, it's considered compatible with the NEC. Thus the internal wiring doesn't need to be inspected for installation under the NEC (read: doesn't actually need to meet NEC rules, just UL 508A rules). Is that right?

Yes.
This is an advantage Listed equipment has over 'build it yourself' stuff.

 

[Eddie702]

I wouldn't consider it a tap if the conductors don't leave the enclosure

 

[jim dungar]

I wouldn't consider it a tap if the conductors don't leave the enclosure

Can you cite an NEC reference that says tap rules dont apply within an enclosure?

 

[omnisciendus]

Jim, thanks for mentioning that! I'd missed that implication.

Eddie, those more experienced can certainly correct me if I'm wrong, but I don't think that matters, since "Tap Conductor" is specifically defined in Article 100 as any non-service conductor that's smaller than what its normal overcurrent protection would allow.

 

[Eddie702]

Isn't an industrial control panel a factory-built piece of equipment tested to UL or other standards? Similar to a AC unit. The nec does not apply to the wiring inside the unit or panel only to the power supply to it.

 

[don_resqcapt19]

Isn't an industrial control panel a factory-built piece of equipment tested to UL or other standards? Similar to a AC unit. The nec does not apply to the wiring inside the unit or panel only to the power supply to it.

The definition is pretty broad.....a simple two button start stop station is an industrial control panel. There is no NEC requirement for it to be listed.

Industrial Control Panel.
An assembly of two or more components consisting of one of the following: (1) power circuit components only, such as motor controllers, overload relays, fused disconnect switches, and circuit breakers; (2) control circuit components only, such as push buttons, pilot lights, selector switches, timers, switches, and control relays; (3) a combination of power and control circuit components. These components, with associated wiring and terminals, are mounted on, or contained within, an enclosure or mounted on a subpanel. (CMP-11)