He locks out the Disconnect (480 Volt Three Phase) He wants to change or Check Mtr. He trys Pushbutton Mtr. Doesn't start. Is he now free to work on that mtr.?? Or is he required to check to see if there Pwr to it ?? Another works Lockout tag out is complyed with . Does arc Flash come into play?
Lockout tag out is complyed with . Does arc Flash come into play?
If feed to motor is loto,within site and confirmed off, I would say no. The disco should be opened and the load side checked and confirmed (by more than 1 method and tool),This would not require AF protection either IMO, based on the fact the line side has the arc shield in place.
On a side note, (not to hijack). I came across a VFD repair this week,Someone else started the repair. I did my visual then test, I noticed they LOTO the 100A disco on the LOAD side of the VFD! So apparently they were lucky, Because the line side (200A 480/3P) was still HOT!!! This leads me to believe that the individual was NOT "Qualified" to work on it.
Using a control button to verify lack of power is not a good idea. There may be interlocks that prevent the control button from starting the motor. You may have locked out the wrong motor and you could be in danger. You should verify no power on the load side of the disconnect and you will need both arc flash and voltage protection PPE to do this. All of the PPE is required until after you have verified a de-energized condition. Don
If the motor is wired correctly then, checking voltage is not required unless it is company policy. However pending on the circumstances I would still check. I have seen stuff mickey moused together and I have seen disconnects failed. Another way to look at it is just because you throw what you presume is the proper disconnect, are you willing to bet yours or someone elses life that it is safe to work on?
I always check everything before I work on it. I carry a non contact testet with me, if I get any response at all from it I go get the meter and do some further checking. Simply opening a disco. does not mean the motor is disconnected, I have seen them break, handle in off position load side hot. Never assume the disco. is wired correctly either, I had one with a blown fuse in it, turned it off, checked with meter it was still hot on line side. Someone had wired line in to the load side, could have gotten nasty.
Life is tough, Life is tougher when you are stupid
Wow. some interesting responses there, and yes saprkyinak that is an OSHA requirement.
Don has it right, LOTO, verifiy no voltage (Check your meter before and after on a known live source. Shock and Arc flash protection is required to be worn by the QUALIFIED person 9per NFPA 70E) to do the voltage check. Also if there is a chance oh induced voltages (Inductive coupling) or stored energy sources (Like a capacitor in a VFD) the protective grounds must be applied that are rated for the available fault current in the system before touching the conductors.
OSHA 1910.269 and NFPA 70E
MV/HV Testing Specialist, "BKRMAN"
#174532 - 02/07/0811:19 AMRe: Working on a Mtr( Maintance man)
Not to throw stones here and I still could still be wrong. 1910.269 is under electrical distribution. The OP was a maintenance question which typicallay falls under subpart S of 1910. (the .300's). Also NFPA 70E is only applicable if adopted by local juristdiction and or by company policy. It may sound I am arguing the case that it is not required to check to see if the power is truely off even if the safety switch is off, I am not. All I am say here is as much time I have spent in Subpart S, dealing with legalitities of code enforcement, and how OSHA writes and enforeces thier rules, I do not think, and like I said I could be wrong, I can not currently say that OHSA specifically requires "test before touch".
I say this because OSHA tries to stay away from making specific statements. They like to stay as broad as possible and leave the specfic rules up to the local jurisdictions. Also OSHA just revised 1910 subpart S just last year. To sum up the revised subpart S, OSHA inspectors are going to be "electrical inspectors" too. This is going to be fun to see how it is going to play out. We got OSHA and now house inspectors playing electrical inspectors. Sorry for the segway. In short you can not presumes the OSHA rule requires this. It should be adpopted by policy just to C.Y.A. If it is currently a safety issue of some sort, then the person needs to cafefully go though the manusha of only the applicble rules, regs, and polices. I will go through Subpart S later and see what I can find. stay tuned.
Verification of deenergized condition. The requirements of this paragraph shall be met before any circuits or equipment can be considered and worked as deenergized.
A qualified person shall operate the equipment operating controls or otherwise verify that the equipment cannot be restarted.
A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage backfeed even though specific parts of the circuit have been deenergized and presumed to be safe. If the circuit to be tested is over 600 volts, nominal, the test equipment shall be checked for proper operation immediately after this test.
A and B seem to be in conflict. I can't see using the controls to verify a deenergized condition. How would you account for interlocks that may prevent the operation of the equipment at the time you operate the controls and may permit the machine to start later when, for some reason, the interlocks have been satisfied. Don