We have numerous 12,470 and 4,160 volt to 480 volt transformers that we need to maintain. To get the oil sample we have to open the energized secondary 480 volt cabinet on the trans. to access the sample port/valve. The exposed hot terminations/taps are only 1 to 2 feet away from the electrician when getting the sample. Does this procedure require arc and shock gear while in this energized transformer cabinet per the NFPA 70E and or OSHA?
Transformer Matinence
- Thread starter session88
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zog
Senior Member
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- Charlotte, NC
Yes and no. You do need the right PPE but doing this energized is not justufibale in 99% of the systems out there. While it used to be common place to draw oil samples energized on pad mounts it is no longer acceptable per 70E and OSHA and I knwo more than one testing company that has been cited for this.
Some of our trans. can be de-energized to get the oil sample and some cannot.
Are there similar threads that might help me determine what type of PPE we should be wearing inside these energized transformers?
I never could figure out how to quickly search for previous threads in this forum.?.?.? I have better luck Googling for a previous Mike Holt thread. Thanks.
Are there similar threads that might help me determine what type of PPE we should be wearing inside these energized transformers?
I never could figure out how to quickly search for previous threads in this forum.?.?.? I have better luck Googling for a previous Mike Holt thread. Thanks.
zog
Senior Member
- Location
- Charlotte, NC
How can they not be de-enrgized?
You are going to have to do an arc flash analysis to determine the PPE required, which will be >40cal/cm2 in most cases. You can't use the tables because you don't have an OCPD between you and the source and don;t meet the limits of the tables. This is liekly the most dangerous job that testing companies used to do, arc flash calculations were a huge wake up to those who did this task. In many cases, thee is no PPE that will protect you.
What many companies have been doing with these is shutting down the transformer and retrofitting the sample valve to the outside of the enclosure, so for future samples you don't need a shutdown.
You are going to have to do an arc flash analysis to determine the PPE required, which will be >40cal/cm2 in most cases. You can't use the tables because you don't have an OCPD between you and the source and don;t meet the limits of the tables. This is liekly the most dangerous job that testing companies used to do, arc flash calculations were a huge wake up to those who did this task. In many cases, thee is no PPE that will protect you.
What many companies have been doing with these is shutting down the transformer and retrofitting the sample valve to the outside of the enclosure, so for future samples you don't need a shutdown.
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