In Electrical Safety there is no Category 0 anymore correct?Has the clothing changed?

Baker in Virginia · Mar 30, 2017

Good Morning ,

I need to revisit electrical safety in our plant. I understand that Category 0 is longer in play , correct ? So it is only 1,2,3,and 4 , now ? Has the clothing changed any ? Do you have any simple links or charts you can share ? I have attached a chart that is from 2012. We have some small panels with 480 vac with about 3-4 frequency drives no bigger than 3 HP . I imagine that Category 1 clothing is still needed for these panels ?

Thanks so much,

jstolaruk · Mar 30, 2017

Cat 0 is still out there, I still see it believe it or not. All depends on the safety assessment / risk analysis.

James Mcquade · Mar 30, 2017

As I understand it, the ARC Flash requirement for any
electrical panel is based on the calories per square cm that can be generated
during an arc flash incident.
I am not even going to try to explain the formula, I just don't know it.

the requirements for cat. 0,1,2,3,4 gear are to much to keep up with, so we only have cat 2 and cat 4 gear here.

if I am wrong, someone please correct me.

james

Baker in Virginia · Mar 30, 2017

Thanks. What is the electrical meaning for " Calories" , I know it means energy. I am sure the calculation is very involved.

Mickey · Mar 30, 2017

Baker in Virginia said:
Thanks. What is the electrical meaning for " Calories" , I know it means energy. I am sure the calculation is very involved.

http://forums.mikeholt.com/showthread.php?t=152308

Lynx777 · Mar 30, 2017

"Calories" is the unit of measure for the energy released during a arc flash event. In my plant we had the full analysis done and over 90% of our panels are Cat. 0.

Mispeld · Mar 30, 2017

One (1) calorie is approximately equal to 4.2 watt-seconds. In the case of an arc flash event, the time is extremely short but watts can be very high if sufficient short circuit current is available.

jraef · Mar 30, 2017

there is no cat 0 any more, that's correct. There is, instead, a "No PPE required", after which you have categories.

Baker in Virginia · Mar 30, 2017

Thanks ,

"there is no cat 0 any more, that's correct. There is, instead, a "No PPE required", after which you have categories."

What categories would they be , for no PPE ? Would they still be 480 vac panels ?

jraef · Mar 30, 2017

It's all different now, since they also removed the "task tables". So now you do a risk assessment and if there is no risk, there is no PPE required. The rules leading up to all this are way way too complicated to go over in a forum like this though.

That said, it's a fair bet that if there is 480V inside, opening the door with the line power live will never be a "No PPE required" situation.

By the way, the change in the clothing took place in 2012, eliminating FR clothing and requiring Arc Resistant (AR) clothing. So if you didn't catch that change in 2012 (as la lot of people didn't), bows the time to update.

Baker in Virginia · Mar 30, 2017

Thanks so much . That is good information.

mk42 · Mar 30, 2017

The way it was explained to me why cat 0 went away was that cotton was better than polyester for sparks, but when it came to a real arc flash it would all burn either way. The instructor said you'd literally be better off naked, at least it might not get to your back that way.

Saturn_Europa · Mar 31, 2017

jraef said:
It's all different now, since they also removed the "task tables". So now you do a risk assessment and if there is no risk, there is no PPE required. The rules leading up to all this are way way too complicated to go over in a forum like this though.

That said, it's a fair bet that if there is 480V inside, opening the door with the line power live will never be a "No PPE required" situation.

By the way, the change in the clothing took place in 2012, eliminating FR clothing and requiring Arc Resistant (AR) clothing. So if you didn't catch that change in 2012 (as la lot of people didn't), bows the time to update.

We paid an engineering firm to do Arc Flash studies of some of our gear in 2013. They listed almost every bucket in one of our major 480v MCCs:

"Flash Hazard Category: 0"

Which I never understood or agreed with. But thats what it was listed as. I told my guys that the minimum rating required was Haz Cat 2 when 480 v was involved.

Now that Haz Cat 0 is removed. Does an additional study need to be conducted?

In Electrical Safety there is no Category 0 anymore correct?Has the clothing changed?

Baker in Virginia

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