NFPA70E and PLCs

A bit off topic, but I'm wondering how other companies handle 70E. The way I read 70E, rubber gloves are needed for anything above 50 volts. Using gloves to check out 120 volt I/O seems a bit excessive. Comments would be greatly appreciated!

Glad its not just mine problem. The approach our company took - rubber gloves for only above 120VAC stuff, such as MCC with 460VAC. Actually NFPA70E has a protective equipment split on energy levels and type of work. Let say for 120VAC circuits testing, I believe no gloves are required. But again coveralls or special shorts may needed anyway.
In any way try to get your safety guy to worry about it

Our safey guy has spoken and he wants us to use rubber gloves. I'm hoping some one has valid argument, that gloves are not needed for 120v control power circuits.

Well, at the sort of resistance the human body presents, I'd think that rubber gloves is kinda extreme for 120v. But from experience, I can say that 120v crossing even a small part of your body can be rather unpleasant (house wiring, grabbed a recepticle across the posts thinking that the power was still off, but someone had turned it on).

I don't disagree with that. My issue is using gloves to measure 120vac. I have a insulated Fluke meter with insulated leads and I'm being told I also have to wear gloves. Sure the gloves will prevent a shock hazard but the decrease in manual dexterity and sensitivity IMHO creates a greater hazard.

NFPA 70E 130.2(C)says "No qualified person shall approach or take any conductive object closer to exposed energized electrical conductors or circuit parts operating at more than 50V or more than the Restricted Approach Boundary unless..." adequate insulation exists. Is your company willing to defend, in a court of law, their posisiton that insulated test leads are 'adequate' at 120V.

If you have not conducted an arc flash analysis, you are probably working under the 'task tables' 130.7(C)9 which requires rubber gloves when voltage testing.

Cornbread you're lucky. If I want to open an MCC just to take a quick peak inside, our company policy is that I have to gear up with coveralls, gloves, NASCAR hoodie, safety glasses and hard hat with faceshield. I've gotten used to it but the response time to motor overloads takes a bit longer!

No dispute with using the full blown PPE in a MCC bucket where you have real possibility of an arc flash. I'm talking at the I/O card level, if I want to make sure I have a valid signal in or out I'm being told I have to wear rubber gloves. Whats next, I'll have to wear gloves to plug my laptop power supply into the wall outlet?

I don't disagree with the comments that 70E does force you to wear gloves and it seem based on the replies that this is indeed the case. I was hoping there was some exemption when using insultated test leads to test for voltage. I have read on other forums where some folks have used the proximity voltage meters (tick tracer) to skirt around the glove issue. 70E says avoid contact for 120v circuits and the tick tracer does not need to make contact, hence contact avoided. I personally prefer a meter to a tick tracer.

Jim Dungar said:

NFPA 70E 130.2(C)says "No qualified person shall approach or take any conductive object closer to exposed energized electrical conductors or circuit parts operating at more than 50V or more than the Restricted Approach Boundary unless..." adequate insulation exists. Is your company willing to defend, in a court of law, their posisiton that insulated test leads are 'adequate' at 120V.

If you have not conducted an arc flash analysis, you are probably working under the 'task tables' 130.7(C)9 which requires rubber gloves when voltage testing.

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I added the bolded text. So, if the panel is finger safe are gloves still required?

About 15 years ago, the company I was then working for had an incident where a service tech - with 15+ years experience - accidently brushed the 480V studs on an instrument transformer while putting the covers back on wireway in the panel! He was out of work for about 10 weeks. He broke both arms when he was thrown to the steel decking he was standing on. Since then, I insist on finger safe in everything I build.

So... if the panel is finger safe does that change anything?

What's your life worth?

Two items that NFPA 70e addresses: Shock and Flash/Blast.

Flash PPE is designed to make it so you may survive an incident with SECOND DEGREE BURNS, you will survive but be badly scarred and in quite some pain, if you have at least the minimum PPE for the known incident energy (You have calculated this or know what it is for each piece of equipment, correct?). If you have never experienced copper plasma, count your blessings and do all you can to make sure you are not involved in an incident, it will be a significant emotional event in your life. Mine occurred 10/17/1997.

Shock is not as "glamorous" as flash but if you can't let go of the live circuit, you can die. The gloves are to help minimize your chance of shock. How much current can be fatal? Less than 50 mAmps, and few of the circuits are fused this low. Without PPE, it's like Russian Roulette, are you feeling lucky today?

The law was created because too many people were having accidents. It has reduced electrical accidents significantly since it was enacted. I agree it seems a hassle to "suit up" every time you are above 50V but just two weeks ago I went into a "safe" 60 A disconnect that actually went straight to a 600 A 480V substation circuit breaker as it was not wired per the building's electrical drawings. Was I ever surprised and glad I had followed our company's policy when I measured 277V from phase to ground.

Sorry for the rant, I was at one time of the "it can't happen to me/ it's too much of a hassle" group but have seen the light.

ps. Don't forget the hearing protection when you suit up, my ears still ring occasionally from my event.

We have this issue here as well we purchased the gloves then they conveniently disapeared so my question is due to the awkwardness of the gloves would electrical insulation mats satisify the above mentioned code?

Paul T said:

I added the bolded text. So, if the panel is finger safe are gloves still required?So... if the panel is finger safe does that change anything?

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It is your company that creates its own work rules. If your company is willing to fight a lawsuit on finger safe being acceptable, go for it. But, remember when the probes are inserted into the finger safe opening you are now making contact with energized parts. Personally, I feel that insulated probes with finger guards on them (i.e. Fluke's TP220) should be sufficient at 120V, but I am not the one making company policy.

Small example of what copper plasma can be like:
http://www.youtube.com/watch?v=S2E2ezZ2t_I
Alternately:
http://www.youtube.com/watch?v=W6Im7PLduwc

The second one, one of my teachers showed us. It's a pretty powerful example of how bad things can be. Luckily, I believe the guy made it through that one.

After having felt 120v across my hand, I have no desire to feel anything worse than that. I was lucky enough that the shock was only across my hand (between thumb and one of my fingers) because it could easily have done a lot worse. In a panel, it's a lot easier to touch something, and end up with an unpleasant potential across your body.

Bobbias said:

Well, at the sort of resistance the human body presents, I'd think that rubber gloves is kinda extreme for 120v. But from experience, I can say that 120v crossing even a small part of your body can be rather unpleasant (house wiring, grabbed a recepticle across the posts thinking that the power was still off, but someone had turned it on).

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What ? you didn't replace your house's bkr panel to accept a padlock, and then put a lock on the circuit breaker to work on an outlet =)


(intended purely a humorous comment - I'm sitting through 8h of safety training today and the sarchasm needed to be bridged =)

Anyone who believes that 120 VAC won't kill is living in a fantasy world. Given the right conditions (sweaty hands, cuts on hands, current path) 120 VAC will kill.

You should be doing a arc flash analysis on your system to verify what the proper PPE is.

I also believe finger safe with the proper leads are acceptable, but an inuslated mat is NOT acceptable.

The thing you should be working towards is what I've spent years doing, converting all your field I/O to 24 VDC. There is no problem with working on 24 VDC with your bare hands.