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Author Topic: Connected ground required for all lighting fixtures?  (Read 5345 times)

Brian Jojade

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Re: Connected ground required for all lighting fixtures?
« Reply #20 on: January 12, 2024, 01:12:26 PM »

Government stepped in and fixed everything.

Damnit, you owe me a new keyboard and a new cup of coffee.
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Brian Jojade

Steve-White

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Re: Connected ground required for all lighting fixtures?
« Reply #21 on: January 12, 2024, 01:24:58 PM »

Damnit, you owe me a new keyboard and a new cup of coffee.

:)
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Dave Garoutte

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Re: Connected ground required for all lighting fixtures?
« Reply #22 on: January 12, 2024, 01:28:41 PM »

"The regs follow the dead bodies."

Unfortunately, that's truth Frank - well stated.  I see it all the time in the racing community - somebody has to die first.

On the flip side are things like gasoline cans.  After a big winter storm in the east coast circa 10 years ago, may bought generators, had no clue as to safe operation so there were fires.  Government stepped in and fixed everything.  Now we have gasoline cans that are in large part useless and at best very difficult to use.  Fortunately, the racers haven't screwed that up so youj can still buy racing fuel cans that work.

Every time I go to fill my genny, I curse the 'safety' features.  I swear I spill more gas WITH them than I ever did without them.

My favorite post lawsuit 'fix' is:  There is a sticker on my roll type hand towel dispenser that says:

 "Warning: Do not attempt to hang from towel, or insert your head into the towel loop. 
Failure to follow these simple instructions can be harmful or injurious." 

Well some idiot must have and sued, and won!
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Steve-White

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Re: Connected ground required for all lighting fixtures?
« Reply #23 on: January 12, 2024, 01:44:53 PM »

Every time I go to fill my genny, I curse the 'safety' features.  I swear I spill more gas WITH them than I ever did without them.

My favorite post lawsuit 'fix' is:  There is a sticker on my roll type hand towel dispenser that says:

 "Warning: Do not attempt to hang from towel, or insert your head into the towel loop. 
Failure to follow these simple instructions can be harmful or injurious." 

Well some idiot must have and sued, and won!

Let us not forget the Proposition 65 warnings on everything - must be saving thousands upon thousands of lives by putting crap that nobody pays any attention to in/on the object or box.
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Russell Ault

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Re: Connected ground required for all lighting fixtures?
« Reply #24 on: January 12, 2024, 07:31:40 PM »

{...} I once asked a fellow at Underwriter’s Laboratories (UL) about this and got the following answer. Electrical safety standards are to a large extent driven by accident statistics. {...} {emphasis added}

Good to see that they're living up to their name, I guess? (Although—given this—I would suggest that these regs aren't following bodies, per se; they're following claims.)

-Russ
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Jonathan Johnson

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Re: Connected ground required for all lighting fixtures?
« Reply #25 on: January 15, 2024, 12:26:55 PM »

Unless you're willing to open up the fixture to prove that the grounding terminal on the IEC connector is not connected to anything internally, assume that it is required.

I'd kind of expect that, if nothing else, it's connected to the shield of the DMX connector. That's not a bad idea, to reduce fault current that might otherwise return on the shield.

I'd like to make a point here: it's commonly said that "electricity takes the path of least resistance." This isn't true; electricity takes all available paths in inverse proportion to resistance or impedance.
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John Roberts {JR}

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Re: Connected ground required for all lighting fixtures?
« Reply #26 on: January 15, 2024, 12:45:27 PM »

Unless you're willing to open up the fixture to prove that the grounding terminal on the IEC connector is not connected to anything internally, assume that it is required.

I'd kind of expect that, if nothing else, it's connected to the shield of the DMX connector. That's not a bad idea, to reduce fault current that might otherwise return on the shield.

I'd like to make a point here: it's commonly said that "electricity takes the path of least resistance." This isn't true; electricity takes all available paths in inverse proportion to resistance or impedance.
That is a distinction without much difference... electrical current flow is a lot like water flow. Water spraying from an open hose in the yard, will generally find the lowest available path, but everything in its way can get wet.   :o

If the SKU has a metal chassis you can probably confirm a line cord safety ground connection with a VOM.

I would caution against making sweeping ASSumptions one way or the other.

JR
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Scott Hofmann

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Re: Connected ground required for all lighting fixtures?
« Reply #27 on: January 15, 2024, 02:52:09 PM »

Unless you're willing to open up the fixture to prove that the grounding terminal on the IEC connector is not connected to anything internally, assume that it is required.

I'd kind of expect that, if nothing else, it's connected to the shield of the DMX connector. That's not a bad idea, to reduce fault current that might otherwise return on the shield.

I'd like to make a point here: it's commonly said that "electricity takes the path of least resistance." This isn't true; electricity takes all available paths in inverse proportion to resistance or impedance.

I believe that in most fixtures, the DMX shield is purposefully NOT connected to AC ground to avoid any ground loop issues. In fact, the pin 1 shield is not to be connected to the connector shell, which usually is connected to chassis/AC ground of the fixture.
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Scott Hofmann

Steve-White

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Re: Connected ground required for all lighting fixtures?
« Reply #28 on: January 15, 2024, 05:20:05 PM »

The fixtures are x4 on a T-bar.  These have a plastic housing and use IEC power inlets.  The supplied power cables are bulky and stiff.  I what to clean up the current routing scheme and use SJ cable for the tie-in drops along the bar to allow more flexibility.  For increased flexibility and reduction in build time I would like to use 2 conductor SJ.  Is there an actual reason to need the ground for these fixtures?
Electrical Danger?
DMX malfunction?

Thanks,
David

Circling back on this, not sure if it's been mentioned or not on this thread.  These fixtures mount to a metallic tree and cross bar.  IF, as a manufacturer they can get away with not grounding the mounting bracket they should not be allowed to do so.

Keep that in mind here, and for metal staging and such there are both grounding and electrical bonding requirements.

The very last thing you want is an energized lighting tripod.

Please be careful.

EDIT:  The above comments got me thinking.  I have a couple of junk LED PAR's which are marketed under the brand of SR or Stage Right.  Took DVM and checked for ground continuity and none.  So, I opened it up and took a look inside.  These lights do not have electrical "Pass Through" capability only a single IEC input connector for the power cable.  These lights are not up to ADJ, however probably represent the level of gear.  These lights do not have any connection to the ground terminal on the AC power port.  I would check your lights with a meter for ground continuity just to know.

The idea of this type of lighting fixture mounted on a metallic truss in a commercial use entertainment environment is scary.  Suppose an overhead air conditioning duct started dripping during a show onto the light tree.  I know it's about as likely as a lightning strike - but, lightning does strike.

The two I have will be used as overhead floods on a DJ setup and hung from a grounded truss.

Picture of the innards of a plastic SR LED PAR attached.
« Last Edit: January 15, 2024, 06:12:42 PM by Steve-White »
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David Allred

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Re: Connected ground required for all lighting fixtures?
« Reply #29 on: January 18, 2024, 12:55:11 PM »

I have a few of those pars, to keep the power simple I daisy chain them as they have an iec in and out socket.  I would think that is an easier and safer way.

The fixtures have the power in and out on opposite walls, and the same with the dmx in and out.  Daisy-chaining for these would require wires to loop from the opposite side of the fixture (away from the t-bar) to the next fixture.  I want to keep all cabling on or near the t-bar to avoid snags and tidiness.

Circling back on this, not sure if it's been mentioned or not on this thread.  These fixtures mount to a metallic tree and cross bar.  IF, as a manufacturer they can get away with not grounding the mounting bracket they should not be allowed to do so.

Keep that in mind here, and for metal staging and such there are both grounding and electrical bonding requirements.

The very last thing you want is an energized lighting tripod.

Please be careful.




The ground is connected to the outer lens plate and to one other location... but can't recall off-hand to what.  Hard to imagine that it is to the brass insert in the plastic housing and relying on the plastic-handled bracket knob's threads to make enough contact against the painted bracket to ground the t-bar and stand that are fitted with plastic connectors.  I don't think any metal from the t-bar touchs any metal of the 2-stage height adjustment stand.  Or that the 3 metal tubings ever touch metal to metal.
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ProSoundWeb Community

Re: Connected ground required for all lighting fixtures?
« Reply #29 on: January 18, 2024, 12:55:11 PM »


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