Ul5081

[Dale Hayes]

We have an Industrial Control Panel rated at 480V, 3phase, 400Amps. The control panel has a 65kA SCCR rating.

We are wanting to attach a 4000BTU air conditioner to the side of the Industrial Control Panel. The air conditioner can be purchased as either a 480V 3-phase or a 120V single phase model. The air conditioning unit is rated for 5KA SCCR.

We must keep the 65kA SCCR panel rating.

So ..... I can either connect a 480V air conditioner to the main 480V power supply or I can use a 480/120 step down control transformer for a 120V air conditioner model.

Is the 480V/120V step down control transformer the best approach since transformers are exempt from SCCR ratings provided that they are fused properly on the primary connections?

I must keep the 65kA SCCR rating on the Industrial Control Panel. What are my options for wiring the air conditioner?

 

[ron]

You can use a step down transformer (120V A/C) or an isolation transformer (480V A/C), both will reduce the fault current significantly and I guess take advantage of the exemption you mention (I'm not familiar with the exemption).