PPE - Opening Utility transformer to place split core CT's on the wiring

aelectricalman

Senior Member
Location
KY
Does anyone know the proper PPE category for the following:

12.47KW Primary
480 Secondary

Opening the hinge on the utility pad mount XFMR to place the split core CT's around the wiring (insulated wiring).
Shut the lid.

Thanks.
 

aelectricalman

Senior Member
Location
KY
Here it is live.

Here it is live.

actual XFMR.png

I will have to finesse the wiring a bit. (right side) In fact i may be able to place them on the bus bars above. This will alleviate the finessing i will need to do to get them around the wiring.
 
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zog

Senior Member
Location
Charlotte, NC
Obviously class 0 gloves for shock protection, maybe class 2 gloves if you are reaching within the RAB of the 12.47kV. But that is the least of your concerns, you are going to have a serious are flash hazard there since there is no OCPD that will clear an arcing fault on the secondary within a reasonable time, you would default to 2 seconds, and your fault current will be based off the transformer kVA, so to know for sure you need to do an arc flash analysis but I will save you time, expect it to be >40 cal/cm2 (Pretty sure it would be if you did the study) so really no PPE will provide protection from an arc flash.

I don't see how you can justify doing that energized
 

aelectricalman

Senior Member
Location
KY
Obviously class 0 gloves for shock protection, maybe class 2 gloves if you are reaching within the RAB of the 12.47kV. But that is the least of your concerns, you are going to have a serious are flash hazard there since there is no OCPD that will clear an arcing fault on the secondary within a reasonable time, you would default to 2 seconds, and your fault current will be based off the transformer kVA, so to know for sure you need to do an arc flash analysis but I will save you time, expect it to be >40 cal/cm2 (Pretty sure it would be if you did the study) so really no PPE will provide protection from an arc flash.

I don't see how you can justify doing that energized
Good information. Thats why i asked! thanks.

Bob,

Do you have anything to add?
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Good information. Thats why i asked! thanks.

Bob,

Do you have anything to add?
Just my two cents worth...
Why are you reaching in a utility transformer?
Those bars are hot and uncovered. 480 isn't a nice voltage to play with. Your fault amps will be extremely high, I doubt you have enough PPE for the job. No offense meant here, but I doubt you are better at working inside these things than I am. I have been working in the utility field for over twenty years, I wouldn't do it hot, period. Neither should you. Have the utility pull the jacks for ten minutes, it will save you a lot of headache, and more than likely your life.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Does anyone know the proper PPE category for the following:

12.47KW Primary
480 Secondary

Opening the hinge on the utility pad mount XFMR to place the split core CT's around the wiring (insulated wiring).
Shut the lid.

Thanks.
Something else after reading your profile...
You wouldn't be taking readings for power factor would you? Looks like a rope CT would be better for the application than a split core either way.
I have connected rope CT's for a metrosonics recorder while the XF is hot. Still went below the exposed bus bar. 30,000 volt gloves, 30,000 volt sleeves, and class 2 FR clothing. (our standard issue)
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
View attachment 7289

I will have to finesse the wiring a bit. (right side) In fact i may be able to
place them on the bus bars above. This will alleviate the finessing i will need
to do to get them around the wiring.
i'm looking at the picture, and 12kv is 2'0" closest point of approach... so
to get into the secondary side with the primary side open you need to be
gloved for 12KV. that's off the osha tables...

now, the arc flash issue.... as has been mentioned, you are looking at
the sunny side of 40 calories.... when i got my arc flash training, it
was mentioned that calorie suits above 40 were not used because
the blast will probably kill you from the pressure wave. internal organs
ruptured, etc.

i am far from an authority on this subject, but this looks like a poor game
strategy... you fault the secondary side hard, and it really won't matter
what ppe you are wearing.

closed casket is closed casket.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
The primary side shouldn't be an issue, because it shouldn't be open while you are installing the ct's, it would be a whole lot easier and safer to go ahead and just shut the transformer down, and install them on the buss bar. What is this running that is so important that it can't be shut down?
 

spark master

Senior Member
Location
cyberspace
The primary side shouldn't be an issue, because it shouldn't be open while you are installing the ct's, it would be a whole lot easier and safer to go ahead and just shut the transformer down, and install them on the buss bar. What is this running that is so important that it can't be shut down?
That water cooler in the lunch room is important. you may be able to pull a hot work permit for that. ;)

me personally, we wouldn't touch that. only the poco has keys for the Pad Mount. and let's say you do get the taps on there ? there where are you running the meter pan, trans S. same conduit ?
 
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renosteinke

Senior Member
Location
NE Arkansas
Not just yes, but 'heck yes.'

Prractice here would involve apron, gloves, face shield, and extended hot stick- even to just flip the 'off handle.' Even though that handle looks like it was designed to be grabbed by a hand.
 
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