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electricalperson

electricalperson

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massachusetts
quick question. is HRC level 2 rated gear all thats needed for 480v 3 phase 3000 ampere switchgear? i plan on buying some ppe for myself soon and im wondering if level 2 gear is all thats needed. im also looking at level 3 but the website doesnt offer any level 3 kits. im not sure if level 4 is overkill or not. i dont want to minimize burning and injuries i dont want to be burned or injured at all in case of an arc flash/blast (if thats possible)
 
electricalperson said:
quick question. is HRC level 2 rated gear all thats needed for 480v 3 phase 3000 ampere switchgear? i plan on buying some ppe for myself soon and im wondering if level 2 gear is all thats needed. im also looking at level 3 but the website doesnt offer any level 3 kits. im not sure if level 4 is overkill or not. i dont want to minimize burning and injuries i dont want to be burned or injured at all in case of an arc flash/blast (if thats possible)
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That may be a quick question but it is not a quick answer, the load has little to do with it. The factors are (simply put) available fault current and clearing time of the protective device.

With 3000A gear I will assume it is fed from a 2500 kVA transformer with about a 5% impedance which would give you about 60,000A of available fault current (Not accounting for any motor contribution). I will also assume the main breaker does not have INST protection, only ST, LT, and maybe ground fault.

The clearing time (At best ) will be 0.2 seconds which using the 70E equitions gives you 54.95 Cal/cm2 at 18", which is above the allowable level (Should be labeled "Dangerous") that the 70E lets you do any work. No PPE can protect you at that level, you could get a 1000 cal suit but it wont protect you from the pressures involved, but at least you can have an open casket.

480V switchgear is usually the worse case senario for arc flash, much worse than anything on the 13.8kV or 4160V part of the system.

P.S. All the numbers in my calcs are estimates and assumed values, but I think you get the idea.

Get some training before working on 480V switchgear!!!!!!!!!!!
 
electricalperson said:
quick question. is HRC level 2 rated gear all thats needed for 480v 3 phase 3000 ampere switchgear?
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By the way you asked your question, I'm wondering if you're working in live 480 volt gear, or planning to?
 
its rare that i work on the switch gear. i wont open it unless its deenergized. but i do work on 480v 200 - 800 amp panels quite frequently. i do use insulated tools and wear the ppe suit but i was wondering if level 2 is alright to use.
 
electricalperson said:
its rare that i work on the switch gear. i wont open it unless its deenergized. but i do work on 480v 200 - 800 amp panels quite frequently. i do use insulated tools and wear the ppe suit but i was wondering if level 2 is alright to use.
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Regardless of levels, what are you wearing from the shoulders up????
 
peter d said:
By the way you asked your question, I'm wondering if you're working in live 480 volt gear, or planning to?
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i work with 480 all the time. i know what im doing and no one can pay me enough money to work in energized switchgear. if i was told to open the gear while it was energized i wouldnt do it. not worth the risk. like i said in my last post i do work in live panels a lot but normally i try to shut them down while i cut a hole or put a breaker in. ive worked with people that used to just put a piece of cardboard over the lugs so no metal shavings hit them or wrap there screwdrivers or nutdrivers with electrical tape to put a breaker in :-? :-? :-?
 
available fault current and clearing time

available fault current and clearing time

How 'bout inductance?

e= -L(di/dt). If L = 1 henry, with a change in i of 100 amps and a clearing time of 1 mS, e = -(1)(100/0.001) = -100 kV.

Parasitic capacitance limits this ideal value but I still don't want to be near an arc like this. The locked-rotor arcs we drew in school were grapefruit-sized fireballs.
 
So if you are not working live on 480V switchgear, and you know what you are doing, why are you asking what PPE level you need when you should know the answer to that?

What exactly are you think of doing?

You are way off base with you PPE!!
 
zog said:
So if you are not working live on 480V switchgear, and you know what you are doing, why are you asking what PPE level you need when you should know the answer to that?

What exactly are you think of doing?

You are way off base with you PPE!!
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i was never taught correctly about ppe. i have a copy of 70e and it says all thats needed is level 2. i was wondering if level 2 is good enough. sorry im not a ppe expert like everyone else
 
I don't ask for the power to be cut when I have to add a breaker, BUT I will if I have to KO from the top of the panel. No questions asked. I have seen people cut in from the top on an energized panel, sorry, you won't find me doing it!!!

Good point EP!!!!!!!!!!!!!
 
zog said:
So if you are not working live on 480V switchgear, and you know what you are doing, why are you asking what PPE level you need when you should know the answer to that?

What exactly are you think of doing?

You are way off base with you PPE!!
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Let's back up a minute zog. NO question is off base on PPE. The more stress we add, the better off our members are!
 
heres what i normally do with 480 volt panels

step 1: get tools from truck
step 2: get ladder depending on size of equipment
step 3: come up with a plan on what i want to do and how to do it correctly
step 4: shut panel down
step 5: slap on level 2 ppe gear
step 6: remove cover and remove cover over the breakers if needed
step 7: measure voltage on busbars to make sure its deenergized
step 8: do the work i planned on doing (punching holes, putting breaker in, pull conductors in)
step 10: megger circuit i pulled in if i done that at the time of doing the work.
step 11: close panel
step 12: turn breaker on
last but least
step 13: smile and go home

whats wrong with that?
 
76nemo said:
You don't wear a hood EP?????
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no i dont wear a hood we dont have one. thats why i would like to buy the level 3 or level 4 kit since they come with hoods. they also sell hoods i could wear under the hardhat and faceshield i could get
 
electricalperson said:
heres what i normally do with 480 volt panels

step 1: get tools from truck
step 2: get ladder depending on size of equipment
step 3: come up with a plan on what i want to do and how to do it correctly
step 4: shut panel down
step 5: slap on level 2 ppe gear
step 6: remove cover and remove cover over the breakers if needed
step 7: measure voltage on busbars to make sure its deenergized
step 8: do the work i planned on doing (punching holes, putting breaker in, pull conductors in)
step 10: megger circuit i pulled in if i done that at the time of doing the work.
step 11: close panel
step 12: turn breaker on
last but least
step 13: smile and go home

whats wrong with that?
Click to expand...


Besides lock out/tag out and an assistant, you hit the nail on the head.
 
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