Disconnect Required for 120 Vac (per CSA) for Panel?

[Skorp1on]

Is there anyone familiar with CSA requirment to provide disconnect switch for control circuit inside NEMA Panel?

Basically, I am dealing with a piece of equipment consisting 600 vac for resistance load and 120 vac (step-down from 600 vac) for control circuit. 600 vac feed to high-voltage panel while step-down transformer feeds low-voltage panel for control circuit.

However, my client wishes to provide separate feed for 600 vac and 120 vac but I am not certain of any single point disconnect requirement for 120 vac circuit.

I was looking at option to disconnect the primary side of step-down transformer and separately feed 120 vac to secondary side but my supplier says CSA may require separate disconnect.

Any help feedback would be greatly appreciated. Sorry for my elementary understand since I am not electrical engineer.

Vin

 

[Kiljoy]

I feel your pain. I work for a machine builder and just got flagged by the Hydro inspector for our control cabinet also not being "disconnected". His solution was to label the higher voltage box (BOX A) and the lower voltage box (BOX B). Then on the lower voltage box, put a label stating that it is fed and disconnected from box A.
In my opinion, this inspector (and yours) is confused between industrial equipment and standard installations. According to NFPA and UL508, the machine is to be considered one object with a single disconnecting means.
The problem with the hydro inspectors is that they never seem to be the same twice. As someone from the States, you just smile and nod, then do what they say.
He also told me to replace my supplimentary breaker with a "real" breaker. It was protecting the secondary of the control transformer.

 

[LionelHutz]

You're asking about feeding 2 seperate circuits, 600VAC and 120VAC, into one control panel. I would install a 120VAC disconnect. It could even be a din rail mount breaker in the top corner with a "Control Power Disconnect" label. It's as much a question of serviceability as a question of code.

DO NOT feed 120VAC into the secondary of the control power transformer (CPT) and just leave the primary disconnected. If you are not using the CPT then remove it from the panel. Shortcuts like that are just plain bad electrical practice. If you are doing the job, do it right.

You're asking about CSA requiring something in a NEMA panel. NEMA isn't a listing agency and CSA doesn't "care" about anything following NEMA standards. So, what is the actual listing that will be applied to the panel?

 

[Kiljoy]

Oh yea, if the step down transformer isn't in the 600V panel then you need a seperate disconnect and warning labels saying that multiple disconnects are required when servicing equipment.

 

[LionelHutz]

Good point - I forgot to post that if there are multiple sources of power then there needs to be a label saying there are multiple sources of power.