Power for Testing Equipment

[Little Bill]

I looked at a job that the customer wants a way to plug in a number of pieces of equipment to test them to see if they are operational. They want to be able to have single phase and 3ph power available on their testing station.
What they would like is some type of box or panel large enough to accommodate several receptacle configurations, both single and 3 phase. They also want this to be portable or a way to disconnect it and move it when not in use.

Basically they want a cord & plug that would supply 3ph power to the box and distribute the power to each receptacle according to the receptacle requirements, some single ph and some 3ph.
They will only be using one receptacle at a time. The reason they want this is they buy used equipment and need to verify that it works before reselling it.

Is there a compliant way to do this?
How would you know how to fuse this not knowing the loads that will be plugged in?
The feed to this would have to come from the overhead bus. So I would need to use the correct size fuses in the bus disconnect. Would the portable box/panel also need OCPD?

Any ideas/comments would be appreciated.

 

[ActionDave]

I think the easy way with no liability worries is to buy an off the shelf item like a Spyder Box. They have different recpts and breakers, gfci and an inlet; pricey but so is your time. You could make your own version if the customer wants custom.

 

[starbolin]

... They also want this to be portable or a way to disconnect it and move it when not in use....
... The reason they want this is they buy used equipment and need to verify that it works before reselling it....

Is there a compliant way to do this?

Not an NEC installation. Not as stated. Would have to be a UL listed assembly under NEC. Unless you are going to try to get in under NEC Article 590.

How would you know how to fuse this not knowing the loads that will be plugged in?

Each outlet would have to feed by an OCPD rated not more than the rated current for that outlet.

The feed to this would have to come from the overhead bus. So I would need to use the correct size fuses in the bus disconnect. Would the portable box/panel also need OCPD?

Yes, one for each group of outlets according to current.

Any ideas/comments would be appreciated.

Back in the day, when Nikola and Tomas were going on about AC vs DC, you had a board with a plug and a socket with a series connected incandescent lamp in which to plug unknown equipment. If the equipment had a short then the lamp would glow brightly but the current was limited to the rated wattage of the lamp. If the lamp glowed dimly then you knew the equipment was safe to plug into the mains.

Later, after you fixed enough toasters, cake mixers and radios, you bought a variac so you could bring the current to a radio up slowly and, hopefully, not burn out the dried-out capacitors.

Now we have solid-state inverter technology that provides variable frequency, as well as variable current and variable voltage. The box I have in my lab costs only like ten grand.

Your customer may want to think about providing a way to detect ground faults.

NEC 590.6(A,B) would apply. Note the grounding monitoring requirements of 590.6(B)

 

[iwire]

Not an NEC installation. Not as stated. Would have to be a UL listed assembly under NEC.

Please cite the code section requiring this to be a listed assembly.

 

[petersonra]

I don't see why you could not do this in a compliant way. Just a matter of feeding the right voltage through the right OCPD to the receptacles. I just finished a design for a box that did this for over a dozen different voltages. It even has a Variac on one of them so any voltage they want can go on the receptacle.

 

[iwire]

I agree with Bob, I the past we have provided this kind of testing station with various voltages, current level and both 50 and 60 cycles.

 

[starbolin]

Please cite the code section requiring this to be a listed assembly.

I'll take back 'would have to be'. It's not in the code, unless 590, because it has a plug and thus utilization equipment and not part of the distribution system. If it were part of the distribution system then what is it? A motor circuit, a SABC, a lighting circuit? It's none because the customer hasn't specified. It's a fancy extension cord. Therefore it's not permitted except as a listed cord assembly, temporary power or customer utilization equipment.

 

[petersonra]

I'll take back 'would have to be'. It's not in the code, unless 590, because it has a plug and thus utilization equipment and not part of the distribution system. If it were part of the distribution system then what is it? A motor circuit, a SABC, a lighting circuit? It's none because the customer hasn't specified. It's a fancy extension cord. Therefore it's not permitted except as a listed cord assembly, temporary power or customer utilization equipment.

the box itself does not have a plug. it has receptacles and thus can be considered to be part of the premises wiring system.

 

[petersonra]

I agree with Bob, I the past we have provided this kind of testing station with various voltages, current level and both 50 and 60 cycles.

Mine has 50 and 60 Hz power too, plus 12 and 24 VDC and 12 and 24 VAC!