# Work on energized equipment



## Chucho (Oct 3, 2007)

When connecting a power meter on a distribution panelboard to obtain maximum demand loads (per NEC 220.87, Exception), is it safer to connect the meter on the distribution panelboard or the dry-type transformer feeding it?

I have been told by electricians that removing the cover of an energized transformer is not safe, but my thinking is that as long as you are a qualified electrician you could remove covers from both transformers and distribution panels.

Any comments?


Chucho


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## sparky970 (Mar 19, 2008)

Even if you are qualified and wearing the appropriate PPE, it would be much better to de-energize the xfmr before doing any work.


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## Chucho (Oct 3, 2007)

NFPA 70E makes a clear distinction between "hot work" and "troubleshooting, testing, voltage measuring". Wouldn't de-energizing the transformer defeat the purpose of taking power readings? What would your power meter read, zeros??


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## sparky970 (Mar 19, 2008)

First of all, it wasn't stated that whether or not this was a permanent installation. If so, it would be smarter to de-energize the circuit to make the connection then turn the circuit back on.


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## HighWirey (Sep 17, 2007)

sparky970 said:


> First of all, it wasn't stated that whether or not this was a permanent installation. If so, it would be smarter to de-energize the circuit to make the connection then turn the circuit back on.


What is this, a trick question on a test?

Permanent install or not, it is always smarter to 'turn it off', and LOTO. No contest.

Myself, as well as most of my lucky surviving electrician brothers, have 'always done it hot' in those yester years. Wake up men. This is year 2008AD. 

As my former great boss and mentor rhetorically asked, "Steve, why do you think there are very few old electricians"?

Best Wishes Everyone


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## Chucho (Oct 3, 2007)

This is not a trick question. It is a real life question that has life hazzard consequences. If I ask my electrician to troubleshoot current and voltage on a 3-phase 50HP motor, what are the readings going to be if there is no power? How can you spot check voltage when the motor is off? Or what, do you turn off the power, open the starter, clamp your amprobe, close the starter, turn it on, and then take the current readings? How, if the meter display is inside the starter? And repeat this procedure three times (one per phase)? This question is not trick; it is a real question that requires a little bit more thinking than the typical "this is 2008AD, turn everything off and then do your work" answer. 

We all need to be aware about the real risk of working on and around energized equipment, but we also need to be able to understand the difference between hot work and troubleshooting/measuring/inspecting.


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## sparky970 (Mar 19, 2008)

Where exactly is this distinction between "Hot Work" and "Testing"? Under table 130.7, work on energized parts including voltage testing is no different and requires the same PPE.


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## Chucho (Oct 3, 2007)

Just to make sure, I am not asking and will never ask an electrician not to wear PPE. The issue is not whether or not to wear PPE. An electrician should always wear PPE while performing his/her work.

The issue is that to troubleshoot or meter electrical equipment, you must work on energized equipment. This type of work does not involve drilling holes on busbars or pluggin in breakers in a panelboard. It is clamping current and voltage sensors.

The question, again, is: would you feel more confident removing a transformer cover or a panelboard cover/door while hot?


For an example of hot work versus troubleshooting/measuring, see NFPA70E 130.1(A)(3).


Thanks all for your responses.


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## sparky970 (Mar 19, 2008)

NFPA 70E 130.1(a) has to do with using an Energized Electrical Work Permit it is not there to say it is okay to use test equipment without PPE. None the less, it would be better to remove the panelboard cover versus removing the transformer cover. What does your electrician say? Is he/she licensed? Are you familiar with electrical work?


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## Chucho (Oct 3, 2007)

*Again, again, I never said I wanted any electrician to work without the proper PPE. *I said NFPA 70E 130.1(A) makes referecence about the distinct requirements between hot work and testing/troubleshooting/measuring.

And thanks for answering my original question: panelboard or transformer?

I feel your comment regarding my familiarity with electrical work as derogative, but nonetheless I will answer: the electrician is C-10 licensed in California with 30+ years of experience. I have a BS degree in Electrical Engineering with 20+ years of design and construction experience, both low and medium voltage, including short circuit, protective device coordination and arc flash analysis.


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## nap (Dec 26, 2007)

> This is not a trick question. It is a real life question that has life hazzard consequences. If I ask my electrician to troubleshoot current and voltage on a 3-phase 50HP motor, what are the readings going to be if there is no power? How can you spot check voltage when the motor is off? Or what, do you turn off the power, open the starter, clamp your amprobe, close the starter, turn it on, and then take the current readings?


Well, now you post an entirely different situation. To check a motor, you open up the starter and check at that point but that is nothing like what you originally asked.

What everybody is trying to tell you is:

turn off the power, open and connect as needed and then reenegize. Since you can't stick with one specific situation. I am not even going to try to answer your question. Each and every situation is different and needs to be treated for what it is.


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## Chucho (Oct 3, 2007)

nap said:


> turn off the power, open and connect as needed and then reenegize.


After connecting the meter, do you put the panel cover back on? If the answer is yes, how can you read the meter display if it's behind the cover? If the answer is no, how is this any safer than not de-energizing? The risk of working with energized equipment exists either by connecting while energized or by measuring while the cover is removed. You could accidentally pull a voltage lead and short two phases.

The reason why I have mentioned this and similar conditions is because no one has been able to understand my orginal question: connect (wearing PPE) at panel or transformer? It is a fact that power meters are typically (but not necessarily) connected to such equipment while energized. 


​


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## nap (Dec 26, 2007)

I took your first post to indicate a hard wired situation and the secon one a temp (hand held meter) situation. My misunderstanding.


to the first situation:

it is almost always safer to test in the panel than in a transformer. The energized parts are too close and have absolutely no protection to prevent accidental touches.

In a panel, as long as the tech is not a blithereing idiot, it is safe to test as you suggest. A technician should be trained to safley perform such a test and make that determination as an individual as to needing to turn off the power or not


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## Chucho (Oct 3, 2007)

Thanks a lot Nap, I just hope my next electrician (my current one is retiring after 30+years) is not a blithering idiot!


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## randomkiller (Sep 28, 2007)

Chucho said:


> Thanks a lot Nap, I just hope my next electrician (my current one is retiring after 30+years) is not a blithering idiot!


 
If the electrician you use has such good knowledge and years of experience, why wouldn't you just have asked him how he would do this job?


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## nap (Dec 26, 2007)

I'm guessing this one is a blithering idiot!

from what chucho posted, it almost sounds like he is trying to figure out how to do something because he did'nt believe the current electrician that he was doing something right while he blew it up.


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## randomkiller (Sep 28, 2007)

nap said:


> I'm guessing this one is a blithering idiot!
> 
> from what chucho posted, it almost sounds like he is trying to figure out how to do something because he did'nt believe the current electrician that he was doing something right while he blew it up.


You know how engineers are, they can give you a blue print and 1000 word written explaination of how to properly pick a nose but not be able to accomplish it
on their own.


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## amptech (Sep 21, 2007)

Some think the glass is half full, some think the glass is half empty, engineers think the glass is too big.


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## JohnJ0906 (Jan 22, 2007)

randomkiller said:


> You know how engineers are, they can give you a blue print and 1000 word written explaination of how to properly pick a nose but not be able to accomplish it
> on their own.



Post of the month! Maybe year! :laughing:


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## RUSSIAN (Mar 4, 2008)

I've opened plenty of panels while hot. I've never opened a transformer while hot and never intend to. Most modern panels are designed to be opened while hot. The way that most transformer covers come off is not conducive to personal safety


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## 3phase (Jan 16, 2007)

randomkiller said:


> You know how engineers are, they can give you a blue print and 1000 word written explaination of how to properly pick a nose but not be able to accomplish it
> on their own.


 
Well there went the soda all over the keyboard!! I need to put that on my toolbox at work, in bold letters:thumbup:


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## randomkiller (Sep 28, 2007)

3phase said:


> Well there went the soda all over the keyboard!! I need to put that on my toolbox at work, in bold letters:thumbup:


 
I call em like I see em. Ever see an EE's work in his own house? WATCH OUT!!!!!!


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## JohnJ0906 (Jan 22, 2007)

randomkiller said:


> I call em like I see em. Ever see an EE's work in his own house? WATCH OUT!!!!!!


YES!


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