240.21 Location in circuit. added text (I) Control Tap Conductors

[James Williams]

Added Text


Article 240 Overcurrent Protection.

240.21 Location in Circuit. Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H) (I). Conductors supplied under 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

…

(I) Control Tap Conductors. Conductors of any size and length meeting the ampacity of the load served shall be permitted to supply signal or control power to indicating instruments, contactors, relays, solenoids, and similar control devices. Control tap conductors can be tapped from branch-circuit, feeder, and tap conductors.

Informational Note: Conductors larger than required for the ampacity of the load may be required for the correct functioning of indicating instruments and relays. Also see 310.10(G)(1) Exception No. 1

Substantiation: Adding “(I) Control Tap Connectors” to 240.21 makes sense because that is the part of the Code dealing with tap conductors and control conductors are often tap conductors. The second reference to "(H)" is intentionally unchanged.

 

[don_resqcapt19]

So that would permit me to tap a 14AWG to a 500 kcmil without any protection at any point.

 

[James Williams]

So that would permit me to tap a 14AWG to a 500 kcmil without any protection at any point.

Sure, unless you want to run 500 kcmil to the panel-mounted voltmeter.

 

[kwired]

So that would permit me to tap a 14AWG to a 500 kcmil without any protection at any point.

Or are they clarifying you don't have to increase conductor size for the "tap" up to the overcurrent protection. I think before this technically you often had to increase conductor size, though listed assemblies like combination motor starters would still tap the power circuit with same size conductors they run for rest of control circuit, but build your own setup you might not be able to do that.

 

[don_resqcapt19]

Sure, unless you want to run 500 kcmil to the panel-mounted voltmeter.

The way I read your proposal, the only protection for the 14 AWG control tap conductors would be the 400 amp OCPD that protects the 500 kcmil conductors. Not seeing why we would want a permission to do that.

 

[James Williams]

Consider a 500 kcmil DC feeder with shunt for an ammeter. The conductors from the shunt to the meter are typically small.

 

[don_resqcapt19]

Consider a 500 kcmil DC feeder with shunt for an ammeter. The conductors from the shunt to the meter are typically small.

Not sure that should be permitted for any application where the conductors from the shunt leave the enclosure where the shunt is installed.

 

[yesterlectric]

I wonder how many instances of this that the original poster is concerned with actually exist in UL listed pieces of equipment vs installed this way in the field. It makes a difference. Could James tell us if he’s having to spend extra money on something to be compliant, or being pressured by an inspector to do more than he thinks necessary?

This even though most times I have seen things like potential inputs in switchgear it goes to a fuse anyway.