Cuts the odds of your buying the farm if you make a dumb mistake. There was that guy at a nursing home who got killed when trying to remove a broken light bulb from a light fixture he thought was dead (the drawings said that all the lights in the room were off the same light switch, but it turned out the building wiring was modified to make that particular light stay on all the time, off an emergency lighting system, and the drawings not updated). Sure, he should have tested that specific fixture, but...
I've had employees deliberately re-energize circuits that were off so as to stun or kill me. ( Drug addicts ! )
In that particular instance, I re-tested -- over and over -- so that when he made it live -- I was promptly aware.
My technique was such that his attempt failed.
I was unable to get him fired... Then.
Subsequently, I fired him. He just couldn't stop with the splif -- right in front of the GC.
So there is a reason for using insulated hand tools.
And then there's the risk that some fool will energize a circuit that should stay dead.
Like the j-man who, having completed the install of an EM exit sign, felt it was up to him to energize the circuit. Two other crews were working on the same EM circuit hooking up other exit signs. ( At height!) Sparks flew. He was canned on the spot. General Foreman had told all lead men do NOT energize ANYTHING until authorized.
I'll admit I'm a tool fool. I have way too many. However, I've seen enough near-death accidents to push my luck.
Many times I'm in situations when I can't figure out how to turn off the power. Yeah, undocumented circuits are the bane of all mankind.
I particularly hate older disconnects -- the cheapos -- that are so cheezy that you've got no working room if it is energized. In such situations, I'm absolutely going to use insulated EVERYTHING.
John, Insulated tools are made for one reason only. In that, they prevent short circuits from live parts to adjacent grounded parts, due to their covered parts only exposing the working parts of the tool. They are advertised as secondary insulation at < 1000VAC Primary insulation is gloves and outers. They are merely part of the puzzle.
I mean, if you were silly enough to drop an un-insulated screwdriver or have it slip from say a bus-bar on to the back of a panel, you'd get all you deserve.
One other thing, I don't understand why you need to get all suited up when a set of simple cover up gear would minimise the risk. All you need is safety glasses, gloves and outers in this situation.
I did an install in a fuel facility where I had to install a bolt-in, molded case breaker in a 208 volt panel. The plant electrician helped me follow company policy. - my voltmeter was tested - power to the panel was locked out at the main switch for the building - power to the building was locked at the main switch for the plant transformer. We took down the entire plant. - I had to wear rated cover-alls, hot gloves and a shield - A look-out man made sure I was okay and ran a flashlight. - when the panel was open we tested for power, but I kept the gloves and shield in case it was re-energized while I was working. This is where the flashlight was needed because I couldn't see in the dark to test for power. - an independent safety inspector monitored the operation and stopped me in the middle to discuss possible hazards (pinched fingers, etc).
Even then, I didn't have to use insulated tools.
#198392 - 01/20/1112:12 PMRe: Insulated Tools: A Waste of Money?
Trumpy ... you managed to find the point I was leading folks to.
The 70E rules call for full arc-flash protection up to the point where you have veirfied that everything is dead. OK, I also think that's over-doing it on your 'usual' panel, but I didn't want to re-open THAT discussion.
Of course, once everything is proven dead, there's no need for gloves - or insulated tools.
Yet, if things are considered 'live,' the use of insulated tools makes no differenct to the mandated PPE.
It appears that the only purpose of insulating tools is to prevent the tool from making a fault itself. The insulation is NOT a substitute for PPE.
John, One other thing, I don't understand why you need to get all suited up when a set of simple cover up gear would minimise the risk. All you need is safety glasses, gloves and outers in this situation.
Trumpy Some arc flash hazards are rated so dangerous that even a bomb technicians blast suit won't ensure survivability. While a 10 calorie cover up might keep you safe in some large percentage of installations, there are lots of services in our secondary network area that require category 4 protection to rack a breaker. We have about 1 square kilometer area in the downtown that has typical fault current of 100ka. These faults can require 40 cal suits which I know you don't want to wear very long without some built in cooling system. If I had to do some live checks close to the source of that system I would be using insulated tools in addition to the rest of the PPR. Working in a single family dwelling with a 200 am 1 phase service I would put on safety glasses and ordinary leather gloves. No synthetic clothing so a pair of jeans and a denim shirt are probably enough. Tape up the shaft of the screw driver and bob is your uncle.
If you’re working on a service, there is usually no way to just turn the power off. For single and multifamily units and even some small commercial, the poco usually just issues you a work order number and gives the OK to cut the Buddco tag, pull the meter, disconnect the drop and do what you need to, then put it all back together and have the AHJ call it in after inspection. They just send someone out to install a seal on the meter can. This system has worked fine around here for many years, so now all of a sudden NFPA 70E declares it to be too dangerous to perform without a full PPE arc suit? P-L-E-A-S-E! I have the necessary gear, shield, hot sticks, gloves and insulated tools, etc., and know how to use them, so will continue to do so when needed. Maybe page one of NFPA 70E should start with: “a licensed electrician that does not know how to safely work on energized equipment under 600V is not a qualified person.”