what safety precautions must be taken when dealing with three phase power?

Answer 1

Isolate and lock off, before working, as with any supplies.

Answer 2

peterphillips - I know this answer probably ain't gonna stop you from doing anything, but if there's anything you're not completely clear about with regard to electrical safety, DON'T DO ANYTHING UNTIL YOU ARE!

NFPA (National Fire Protection Association) 70E is the authority that even OSHA defers to and it's where you go for the full scoop on electrical safety and how to put it to use. This should be your very first stop on your road to elecrtriciandom.

Now, because of the question you're asking here, I'm assuming you haven't read or reviewed this enlightning document, so I'm gonna get real dramatic here and the smart money would heed everything I have to say - and this doesn't even begin to cover every situation, it's just a quip recap of the dangerous part of uninformed "electricianing":

If you're talking about three phase, you're probably talking 220VAC and up and I don't care what ANYONE says, 220 volts can be LETHAL if your body has a good ground, or G** forbid, you've got a wire in each hand. Even more so if you're hot and sweaty. And that's only if you make direct contact. You don't even have to do that to get kilt if you're dealing with enough P. (I times E; look it up if you don't know).

Also, you can have rubber gloves rated for the sun for all they'll help you if you have a live circuit in front of your face and you short phases or ground a phase. Do that and there is the potential for an arc blast that can blind you (permanently!), can cause third degree burns all over your face and body, can throw shrapnel, etc., etc., etc. I don't care if it's three phase, single phase, or umpteen phase, voltage and current are voltage and current and if you don't have the basics DOWN PAT before you start getting into it, you are asking for some very serious trouble.

The message here is, don't even think about getting ready to ATTEMPT to work on a circuit that has even a remote possibility of being energized or even worse, getting that way unbeknownst to you when your hands are in there. There ain't anything manly, cool, gutsy or expert looking about intentionally sticking your hands into a live box to do anything at all. If there was a pro around anywhere when you did that, he would hopefully tackle you.

Now, if you've read all this and you still insist on getting your hands dirty before you have all the requisite know-how, at a very minimum:

1. Have a CPR trained individual with you the whole time you're doing this. If you don't have someone with CPR willing to work with you, then at least get someone who knows how to turn the power off if need be and knows how to call 911.

2. Don't wear that short-sleeve rayon shirt and a pair of your favorite short pants. You should have a long sleeve, 100% cotton shirt and jeans on when you're doing this work. Even better if you happen to have a pair of Nomex coveralls, but I bet you don't. Wear approved safety glasses - Home Depot, 6 bucks in exchange for your eyesight = good deal. Stand on a rubber mat if you got one; that'll help too if you make accidental contact with some 'lectricty by preventing, or minimizing, the path (whcih includes you) to ground.

2. Get a voltmeter that you know is good and that you know is rated for the voltage you're working with - and if it's 600VAC or over, please kiss your Momma goodbye and tell her you love her before you start this. Then, BEFORE you start poking around to make sure your box is completely de-energized, go and open all the upline breakers and pull all the fuses (with a fuse puller!) that feed, or even MIGHT feed into the box, or motor controller, or load center, or whatever it is you're working on. And don't forget about all the other control voltages in there that have to be isolated, besides the big 3 phase power lines.

Once you've done that and you've made sure that some knucklehead can't go re-energize your box when you're not looking and you've made sure that your box is completely dead 'cause you've double-checked it with your verified meter, then you can finally get some work done in relative safety.

I've been an electrician and an electrical engineer for quite awile now and I love working with electricity. It's very rewarding work and always something new to learn to keep it interesting. I recommend it to (almost) anyone as a line of work or an interest. BUT - you GOTTA do your homework first. Get with someone you trust who's been doing it for awhile if it isn't pratical to go and take classes. Read and read and read. Make sure you understand what the NFPA 70E is all about.

If you know how to work safely around electricity and you ALWAYS maintain that healty respect for what it could do to you if you slip up or get careless, electrical work will give you a lifetime of satisfaction and a well paying occupation. Best to you. And BE CAREFUL!

Answer 3

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Answer 4

After switching off disconnect, always measure that the circuit is NOT live.
Lock it out & ONLY YOU have that key to the lock.
There is also the danger of ARC FLASH.
Where safety glasses,gloves clothing as per arc flash class (0-4).

Answer 5

Typical Earthing Arrangements
Identification of protective devices
cable current-carrying capaities
Prospective fault current
circuit load characteristics
Labelling
Isolation And Switching

the list goes on and on mate each is as important as the next.

Answer 6

As the other sparks said,but keep phase colour to phase colour,and if motor runs the wrong way change any two phases,

Answer 7

The same precautions as if you were dealing with any form of electricity, it can all kill you.

Answer 8

Hi,

Make sure your current is running in the proper direction or the motor will run backwards-

T

Answer 9

is this like, the grid?

all i no is, dont piss on it and wear extremely thick rubber gloves, or dont do it at all!