Temporary Equipment Testing

[wireddd]

A friend of mine who works in a plant where they build motor and equipment control panels, asked me what section of the code and osha rules need to be followed when temporarily testing these control panels. Power is 480 volt three phase and is done with rubber cords off of disconnects to the control cabinet. Seems that one assembly line testor got a shock and now they want to review their procedures.
Any help would be appreciated.

 

[bphgravity]

Re: Temporary Equipment Testing

There isn't really anytihng in the NEC that will assist with this problem.

Try reviewing the NFPA 70E, NFPA 79, OSHA 29 CFR 1910 and 1926 and maybe ANSI C2.

 

[plt]

Re: Temporary Equipment Testing

I worked in a shop in Michigan that used chords the same way. I think a good suggestion would be to install an outlet and put a plug end on the chord then run the chord through the side of the panel through a small knock out with a chord grip. Later you can plug it if the hole can't be used for installing power at the customers plant or just open the door on the control panel on the machine and connect the chord then when the test is over you can unplug the chord and remove the wire, shut the control panel and send it off.

 

[harborrick]

Re: Temporary Equipment Testing

For all temp services with control panels.First thing is to make sure your temp power is grounded.That is probably why he or she was shocked.
Take Care Rick

 

[petersonra]

Re: Temporary Equipment Testing

Originally posted by harborrick:
For all temp services with control panels.First thing is to make sure your temp power is grounded.That is probably why he or she was shocked.
Take Care Rick

what do you mean by "grounded"? Do you mean bonding the metal panel via an EGC? Do you mean making sure you create a neutral at the panel?

 

[charlie]

Re: Temporary Equipment Testing

Grounded is really a slang name for connecting the equipment to the grounding conductor (normally the metallic raceway that feeds the equipment). This grounding conductor is really a bonding conductor that takes ground fault current back to the source of a separately derived system or the electric utility's transformer. The grounding conductor is also grounded (connected to earth) at the source. The 2008 edition will (most likely) change the name from grounding conductor to bonding conductor.

 

[petersonra]

Re: Temporary Equipment Testing

I was trying to get to what he meant by grounding.

I am curious just how the tester got his/her shock. Was it on the 480 side or the control side? Did he/she stick a hand where it did not belong?

We often add plexiglass shields over parts that are easy to inadvertantly touch such as distribution blocks or fuse blocks, or use touchsafe devices to avoid this problem. Not always possible to do so though.

 

[templdl]

Re: Temporary Equipment Testing

It is of my opinion that whether temporary of permanently installed the power is applied to the panel and grounded in the same way. NFPA 79, Electrical Standards for Industrial Machinery, (my copy is 1997)does have a section 6, Safeguarding of Personnel, i.e., 6.1 General states that "The electrical equipment shall be procided safeguarding of persons against electric shock both in normal and in case of fault."
Sec 6.2 Safeguarding against shock in normal service, and more.
The Forward of said publication also talks about the risks associated with the hazards relevant to electrical equipment should be assessed as part of the overall requirements.
In a testing situation one would like to understand that the people working on and/or conducting test would be trained and qualified to understand the testing procedures and the risks involved.

 

[petersonra]

Re: Temporary Equipment Testing

I don't see how one could connect power to a panel in testing the same way as when it was installed.

In testing one would be inclined to use a patch cord of some sort rather than hard wiring (hopefully one with a ground wire included and connected at BOTH ends).

But we usually test these things with no load so we typically hook up a 12 gauge patch cord to a 400A MCC, just for testing.

Its a matter of being careful, and keeping other people away while the door is open and energized.

 

[charlie tuna]

Re: Temporary Equipment Testing

i would think that a area that is used to test manufactured equipment would have a sufficient number of panic stations to de-energize the testing power source. and i would also suggest a separate heavy duty flexible ground cable be connected to the frame of the equipment before any test power is applied! similar to what we see in schools and laboratories.

 

[petersonra]

Re: Temporary Equipment Testing

usually we bring in the 480 via a cord direct to disconnect of the panel under test. the source is a cart with an xfmr bank on it that brings the bldg 230V/3ph supply upto 480V, and has its own disconnect.

the transformer bank has its own cord that plugs into a 230V outlet (incl ground) and another cord with pigtails for the 480 side (with ground).