ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades exploding metal halide lamps

Hello Marc,
IMHO, I don't think I would like to work on any lighting fitting that uses more than 230V, above that, you've got some real Health and Safety issues, for people that service these sorts of fittings, especially where these are a long way up from the ground, electric shocks and explosions take on a whole new perspective, when you are 7-8 metres up off the ground.

Most common commercial service voltage in the area of the US I work is 480 phase to phase 277 to ground, transformers used to get it down to 208/120 so we end up with 4 voltages in most commercial spaces.

Small commercial service about 600 amps, a typical grocery we wire 1600 amp, and larger office buildings 3000 amp.

Trumpy, 480 to fixtures is common for high bay fixtures and parking lot / site lights, and florescent office lighting runs 277 volt.

I will tell you I have never gotten hit with 480, but I have gotten a couple of good 277 volt shocks, It hurts a great deal more than 120 volt's.

Incidental references to North American lighting voltages are:
http://www.ruudlighting.com/literature/spec_sheets/td-2.pdf
Lists 120, 208, 240, 277, 347 and 480 volts
http://www.fisherpierce.com/PDFFiles/FP%20SERIES.PDF
RATED VOLTAGE
FP120 Series -- 105-130V, 50/60Hz AC
  (120V Nominal)
FP208-277 Series -- 200-300V, 50/60Hz AC
  (208, 240 or 277V Nominal)
FP240 Series -- 190-250V, 50/60Hz AC
  (220 or 240V Nominal)
FP347 Series -- 310-370V, 50/60Hz AC
  (347V Nominal)
FP480 Series -- 400-520V, 50/60Hz AC
  (480V Nominal)




[This message has been edited by Bjarney (edited 04-14-2003).]

Yes, 347v flor's are horrible to work on, especially at Public Works facilities, and even more so off a ladder.

Last week, due to security reasons (even tho were cleared 'secret') we were not allowed to do the fixture bouncing after hours, which meant power cldn't be interupted.

As an 'apprentice' I refuse to do anything outside of whats deemed 'safe and proper', so needless to say when asked to just go in a bounce a few fixtures I said sure, expecting a simple, relocate the fixture still connected in the ceiling grid and rechain them.

Wrong!!!! The 1st fixture I attempt gives off that scary hummmmmmmmmm when I moved it. Pulled my hands away as it gave off its own lil liteshow, called my supervisor and told him I refuse to touch any of the system live!!!

Well doesn't he come down to the site to show me I'm wrong, lol, and the same happens to him (also lucky not to get hit from the fixture).

So he decides to go to the JB and disconnect that area. All I can say is who-ever authorized the ceiling grid should have been shot for not requesting electrical alterations. EVERY JB was over a grid cross with only about 3" clearance below the open box, data wires all over the place, and venting obstructing safe mannouvering.

Not to forget... who-ever installed this electrical mayday shld also be shot... there isn't a single joint (120/208/347) in the entire building that when you remove the marrets that the wires don't spring apart.

So Mr Bigshot (supervisor) tackles it anyways as I stand below watching at the floor level. Needless to say, as he removed that 1st marret he got energized.

And as this was my first time seeing someone hit with more than 120 I can only say I hope its my last. The look of fear and pain as somebody is hung up would scare the bejesus out of a hardened soul.

I kicked the ladder out from under him, he separated and hit the ground in a curled up tearing fashion. I asked if he was ok, checked for burns, but found no entry nor exit anywhere. And for that, he was VERY lucky as the hot connected with his hand, and he was unknowling grouded at the back on his neck with a BX.

Once he settled down, and was able to get up, and seemed ok, I quietly packed my tools up, called a cab, told him he is a dumbass and too dangerous to work with and to call me when PW is willing to shut the floor lighting down at the panel and consider themselves lucky I don't call the authorities for putting me at jeopardy.

Next day got called in, appologized profusely, and told I wld never be put in or asked to perform in a hazardess manner again.

I'll tell you guys, especially the newbe's out there, watch out for yourselves and use YOUR OWN common sense because I think a lot of the seasoned journey men out there are so used to encountering these types of routines that they tend to fear less as they do the mondane tasks asked of them.

And I'm sorry, I never have trusted a person with a holier than thou additude when it comes to proceedures or safetly and more importantly when it deals with electricity and MY life.

Sorry for rambling or hyjacking people, it was just still fresh in my mind and wanted to put it on paper so to speak.

-Greg aka: don't kill me with stupidity

What causes Metal Halide lamps to explode?

Smokeumchevy,

Remember this, isolate before working on circuits, test twice before working on circuits,

DO NOT TAKE IT FOR GRANTED THAT THE SUPPLY IS OFF, EVEN IF YOU ISOLATED IT YOUR,SELF

CHECK IT !!!


In regard to Exploding metal halide lamps;

the following can cause premature explosion and or failure of lighting lamp.

Incorrect connection of fitting;
over run time ( on to long without a break);
Failing/failed ignitors
Failing/failed PFC capacitors
Failing/failed control gear
incorrct supply characteristics

dropping them on the floor
throwing them at your supervisor.

these are a few of the faults that can cause the above.

Had a bit more fun today;

Local POCO have disconnected the driveway street lighting from there supply, so we are having to route a new cable underground to feed them, lousy fittings though 90 watt low pressure sodium on 5 meter poles, yuk, hate em.!!

Smokumchevy,
A BIG welcome to ECN, mate!
Glad to have you along.
Don't you just love Supervisors?
One thing that does kill and seriously injure experienced Electrical workers, is Complacency.
However, I wouldn't personally kick a ladder out from under a person to free them from contact with live wires, this can lead to even worse injures than the shock.

[This message has been edited by Trumpy (edited 04-15-2003).]

bonsoir trumpy :


yeah indeed we have multi voltage in commercal and industrail system and sometime if not too carefull it will get you by suprised and yeah yeah i got shocked by 277 volts few time and last time i got shocked with 480volts when i working on big parking lot light i did double check the voltage make sure it is dengerized (dead) somehow without waring i got hit with 480 OUCHHHHHH that got me the fixure have unground system i did swear about it and got the inspecter check the rest of system and end up rewire whole parking lot btw the wire was bad and reconnet to 277 volts and add fuse each large fixure they were a 1 kw mh light bulbs each that was big and hevey sucker to boot... anyway main thing i use is common sense what is going on. i work on lighting system for many years and very few mh light did exploaed on me but kinda rare for me because i convented my comster to replace them early before they hit the end of life and last thing i want to deal in middle of wintertime to replace bad ballast that is no fun i allready did it with 20-C temp with wind going about 25 mph ( 40kmt) anyway engough of chat but will chat more later about it

merci marc

Welcome Greg,

Your experience just goes to show that we should never become complacent. I must confess that I've been hit with 240V to ground a few times, but fortunately I've never found myself across two phases.

A good approach to adopt when checking that a circuit is de-energized is to put the meter onto a known energized circuit first.