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 Post subject: 120V Control Systems Arc Flash
PostPosted: Tue May 03, 2011 10:02 am 
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Hi,
I searched briefly for this topic and was unsuccessful. Curious to know what's being done out there to comply with NPFA 70E on 120V (AC and DC)power and indication in industrial control systems. At our facilities we have losts of small boxes and instruments in this voltage range that are regularly opened, examined and tested. Do you rely on work practices or labels to deal with these? What type of clothing do you require?

Thanks,

Casey


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PostPosted: Wed May 04, 2011 4:59 am 
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C. Harman wrote:
Hi,
I searched briefly for this topic and was unsuccessful. Curious to know what's being done out there to comply with NPFA 70E on 120V (AC and DC)power and indication in industrial control systems. At our facilities we have losts of small boxes and instruments in this voltage range that are regularly opened, examined and tested. Do you rely on work practices or labels to deal with these? What type of clothing do you require?

Thanks,

Casey


What is the transformer size supplying these control circuits? Are they like 120 volt PLC end devices? Motor Control??


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PostPosted: Wed May 04, 2011 8:08 pm 
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Yes, PLC 120V digital inputs and outputs, relays, solenoids, etc. Transformer sizes vary throughout the fleet, this is also inclusive of 125VDC.

Thanks,

Casey


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PostPosted: Wed May 04, 2011 8:30 pm 
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For your control voltage concerns...Cat 0 should be adequate, as the transformers and fuses should be low enough to not have an arc flash hazzard... That being said there are still electric shock hazzards and (not sure if it is applicable) explosive atmospheres to consider as well..

Personally I wouldn't be wearing a faceshield when I am testing a pressure switch as there is no arc flash issue...


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PostPosted: Thu May 05, 2011 7:56 am 
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Thanks for the response, that is a reasonable approach.
Is it typical to label this type of equipment or are people relying on a standard/work practice?


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PostPosted: Sun May 08, 2011 8:14 pm 
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I've never seen a label on any of that type of equipment or heard of anyone requiring one, but that is not to say it isn't done...The only pertinant labelling I've seen is that on the Junction Box that lists the voltages (sometimes) or "Voltages present from multiple sources"....


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