SCCR And Sub Enclosures

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Jsantangelo

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I work for an OEM and have a system that has a power drop to the systems main disconnect located in the control enclosure. Also, I have 5 sub enclosures that are fed with either 208VAC 3 phase or 120VAC 1 phase. Do the sub enclosures need to have an SCCR rating and tag also?

Joe Santangelo
 
Article 409.110 requires industrial control panels to be marked with an SCCR. Are these industrial control panels? If so, then yes. It does not change just because they are supplied power from another industrial control panel. Is this what you are asking?
 
I don't know exactly what you mean by a "sub" enclosure, but if it qualifies on its own as an industrial control panel I concur with the poster who said it needs an SCCR evaluation and marking.

if it is just a terminal box, probably not.
 
Perhaps the question here is "Are the panels downstream industrial control panels"? See Article 100 for the definition. There may be a misconception that SCCR is only required for "main" panels and not other panels fed from that main panel.
 
richwaskowitz said:
Perhaps the question here is "Are the panels downstream industrial control panels"? See Article 100 for the definition. There may be a misconception that SCCR is only required for "main" panels and not other panels fed from that main panel.
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Correct. As mentioned earlier article 409 is where you find the requirement of an ICP needing an SCCR, but article 100 is where you find the definition of an ICP. However, 409.110 gives the conditions under which the SCCR labeling requirement applies and in the 4 conditions, there is an exception worth noting here:
Exception to (4): Short-circuit current rating markings are
not required for industrial control panels containing only
control circuit components
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Then if you go back to 100;
Control Circuit. The circuit of a control apparatus or system
that carries the electric signals directing the performance
of the controller but does not carry the main power
current.
Click to expand...

Where it gets a little shady is in the NATURE of your "120V panel". If it is simply relays, push buttons and maybe some electronics, I'd call those "control apparatus". But if it is a 120V panel that turns 120V motors or heaters or other external loads on and off, an AHJ might consider that "power current" and look for that SCCR label.
 
Jraef,

Good explanation. I have to argue this point all the time in my field. Sometimes I think it might be easier to argue law than understand Codes and standards. It is hard to NOT read something into what is written when our own preconceptions and misunderstanding of documented definitions. Often the terms "load" and "control" get questioned. Even though a pilot light presents an electrical load to a circuit, it is not a load which qualifies as a power circuit. It is a control device. The same goes for relay coils, pneumatic solenoid coils and rotating beacons with little motors in them.
 
richwaskowitz said:
Jraef,

Good explanation. I have to argue this point all the time in my field. Sometimes I think it might be easier to argue law than understand Codes and standards. It is hard to NOT read something into what is written when our own preconceptions and misunderstanding of documented definitions. Often the terms "load" and "control" get questioned. Even though a pilot light presents an electrical load to a circuit, it is not a load which qualifies as a power circuit. It is a control device. The same goes for relay coils, pneumatic solenoid coils and rotating beacons with little motors in them.
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Where I find it more challenging from that aspect is when there are 120V motorized valves being fed from a panel that otherwise has only controls. I have defaulted to just going ahead and slapping a label on it that says 5kA SCCR. From an available fault current standpoint, it's hard to have more than that on a remote panel that has only 120V in it.
 
Jraef, I can see your point for sure.

It has been explained to me by our UL guy, that in cases of a motorized valve, the valve is not a "pilot device" and therefore the motor is a load and part of a power circuit.

A solenoid valve it self does no "work", it simply controls the air or fluid which does the work and it is then by definition part of a control circuit.

But I can see how this argument could still be questioned and subject to interpretation.
 
petersonra said:
my argument would be that these are class 1 circuits and thus pretty much by definition cannot be power circuits.
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Well, I think the argument is actually whether they indeed ARE Class 1 circuits or not. Class 1 per 725.41 (B) still says "remote control and signalling circuits" and the issue is still if a valve motor is a control or a power device. I would tend to side with it being control and probably win an argument with an AHJ, but the little 5kA SCCR label is cheaper than getting called back.
 
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