Thoughts on Cat 4 PPE

In our attempt to comply to CSA Z462 as a company, we've bench marked other companies to find out how they have, or are tackling this process.

One interesting comment that one of the companies pointed out during the communication state of benchmarking was the follwoing on Cat 4 PPE.

"Category 4 PPE is virtually a waste of time/money. Anything that nasty should be “live work prohibitedâ€, because the blast pressure at that energy level will likely kill you from concussion regardless of PPE, and the PPE itself is so ergonomically impossible that it likely will cause an accident (dropped tool etc). Many vendors have stopped selling Cat 4 suits for these reasons."

Obviously this company has gone to the point of not purchasing any Cat 4 PPE...my question lies with the fact that even though they prohibit live work on any equipment that require Cat 4 PPE, how can they test that it is not live safely without using the Cat 4 PPE???

Is their view point a common shared opinion of the masses or are they just taking the wrong approach. Any direction would help to make sure we act appropriately when designing our program.

Best regards.

I would not say it is a common point, but the trend seems to be shifting from PPE to mitigation solutions and working in reduced PPE levels. Than again I deal with mitigation projects and remote racking/operations on a daily basis so my exposure may be skewed.

I look at it like this. If you had a hornets nest in your garage is it better to suit up in a bee keepers suit every day to get in your car or just have the dang thing removed?

I think your question is excellent.

Even if you want to work on that cat 4 equipment de-energized, you still need to test it wearing cat 4 PPE.

Unless somedy can find in NFPA 70E or CSA Z462 something that says otherwise?

Depends if the working distance for testing is the same as the one used for getting the CAT 4 rating in the first place. If you can test from farther away, the IE is likely less.

That's true, but that will not help you in every situations.

Dylan Wick still pointed out a fact that people sometimes forget: an equipment must be considered energized until tested de-energized wearing appropriate PPE.

I disagree with the "No Cat IV" philosophy for a couple of reasons.

The first has been stated by others and is the proof of deenergization requires you to suit up.

The second is that many companies use the 2 level approach - e.g. Cat2 and Cat4 are the two levels. Further, many companies go to higher levels than required. At my company, we wear Cat4 gear for all switching operations of medium voltage gear, even when the study called out a Cat2. It simplifies our decision making, increases safety, and the switching operation is easily done in the suit. We don't work meduim voltage hot - period. We have the Cat4 suit on when proving the absence of voltage either through visual means or with a tic tracer. Then we're clear.

So the Cat4 gear is a critical part of our electrical safety program.

TxEngr

Cat 4 PPE

I'm wondering what everyone is doing with Cat 4 PPE when the hazard is more than 40 cal.
Some of my switchgear is +55 cal/cm² so my guys suit up with 40 cal blast suits and 8 cal shirt & pants when switching or racking.
I think the blast would be deadly but the body would look good at the funeral...
Remote opeartion is the way to go but we aren't there yet.
Ideas or comments?

Mitigation. No reason to have a 55 cal.cm2 hazard on anything.

Hi Zog

I absolutely agree. We're running and mitigation is an activity we can only pursue when plant availability dictates. I will be going down that road in the next weeks when the new arc flash study is completed by our consultants. In the meantime, do you think there is a safe way to operate this particular switchgear locally? We are head to toe 40 cal + 8 cal clothing.
FYI 138 KV incoming 138/13.8 120 MVA transformer feeds this switch, NGR makes it safer on a phase to ground fault.

Distance is safety, and remote operators may be the fastest, cheapest, and best solution. You can operate anything outside the arc flash zone wirelessly for about the cost of the PPE you described above for 2 people.

I just got some information from the consultant indicating a rating drop to 3.1 cal if I can clear the fault within 100ms. Due to the location of the switchgear in the one-line, I've suggested that we use a Vamp type relay so I don't mess up downstream coordination. The 13.8 KV breaker clears in about 100ms so I'll be ok once the upgrade is done. In the meantime - no local switching, we'll switch at the 138 KV station. Fun,fun,fun...

You would be better off using an arc flash relay, one using light sensing like ABB's version. 20ms operating time. However, remote switching is still cheaper and more effective, thats what all the utilities are going to lately. You could be set up next week and never operate one of your breakers by hand again, just sit back with your remote and push the button.

Yeah, I looked at the SEL 750A. Clearing time in 4 ms so that will work fine. Not too expensive. Have you heard of CBS Arcsafe? They came by with remote racking gear. I'll most likely do remote racking first then protective relaying next summer shutdown. Do you know of any other brands of universal racking equipment (must be CSA).

Has Zog heard of CBS Arcsafe??
Zog, did you set this up?

The name rings a bell

Hey Zog
Thanks for directing me here. Back where I started with the remote racking issue. I will go with remote racking but I'm having a heck of a time wrapping my head around testing once the racking is accomplished. The Arc Flash Hazard boundary is 146' so a long hotstick with a volt tick is out. Do you know of anything in the market specifically designed to test by remote means?

I don't, there are some sensors on the market that get installed in the gear but they don't meet the Live-Dead-Live criteria for verification.

I have to say I don't know how to approach the test portion of this. Can't get near it to test properly therefore can't prove a de-energised state. Can't engineer out the hazard in less than a year and need to run 97% of the time.

There are mitigation solutions for everything, send me some details.

Situation: I need to test a 138/13.8 KV transformer secondary with an incident energy level of 58 cal. The breaker is racked out remotely using the CBS ArcSafe device, grounds are in on the 138 KV primary. How do I prove the secondary is de-energised to satisfy NFPA or CSA?
Same situation 600 volt MCC main breaker with an incident energy level of 145 cal. How do I test that?

I must test to prove the circuit is de-energised but it is impossible to do it safely?
I can't always shut it off upstream to reduce to cal levels because we're a mine and people are 3000 feet underground, the mill is running and would plug up imediately...