LX Bars

[Thomas]

So, this might be a bit of a strange question, but all of the LX bars I have used are generally made of some sort of metal; either painted black or left as-is, but nonetheless metal. In the event of, say, a janus shorting (the kind you get when crazy tech students make them for you) out against the pipe, the I'd assume the current would electrically charge the bar and all hell would break loose- has this happened to anyone?

[fredthe]

Um... that's the point of having a proper ground connection on every instrument... to protect from this happening.

If you're putting up homebrew equipment, without proper grounding, I hope you have good insurance coverage

[zac850]

Originally Posted by fredthe

If you're putting up homebrew equipment, without proper grounding, I hope you have good insurance coverage

And I hope your insurance company doesn't figure out that everything in the grid was ungrounded.

Otherwise, yes, grounds should exist. And don't have people you don't trust wire your cables.

[Van]

Originally Posted by Thomas

So, this might be a bit of a strange question, but all of the LX bars I have used are generally made of some sort of metal; either painted black or left as-is, but nonetheless metal. In the event of, say, a janus shorting (the kind you get when crazy tech students make them for you) out against the pipe, the I'd assume the current would electrically charge the bar and all hell would break loose- has this happened to anyone?

a Janus ? Is that a Two-fer ?

[TechiGoz]

If you are hanging home-made fixtures (as others have said) they should be properly grounded otherwise there is the risk of having 'all hell break loose' and the bar becoming charged. This would be a bad thing, and the insurance companies generally tend to look into detail into cases like that..

[Chris15]

Are not most lighting bars suspended by metal and that metal in some way earthed? Eg. with a steel grid or a proper earth wire? This should be stopping the bar from getting charged shouldn't it? Or am I on a different wavelength?

[Thomas]

Ok good, bars are earthed so any short will hit the ground and go away.
Janus is an extension cable? Like a 5m run of cable to give you some distance between a wall plug and a fixture? What do other people call this? Industry standard down here..?

[Van]

Originally Posted by Thomas

Ok good, bars are earthed so any short will hit the ground and go away.
Janus is an extension cable? Like a 5m run of cable to give you some distance between a wall plug and a fixture? What do other people call this? Industry standard down here..?

Oh ok I thought, Janus = Two faced God and translated that to Janus = two-fer < one male----> two females. > ( the french have another word for that > Maybe Janus started out as a trade name ? Like Crescent Wrench.
Just another one to file under the interesting Nomenclature file. BTW a 5m cable in the Cinematic world would be a "stinger"



As to the "Earthing" < grounding here in the states> Just because the grid and LX bars have a path to ground doesn't mean you can't get a buzz from them. All cables and All fixtures must be properly maintained and Grounded < earthed> to maitain the safety/integrity of the electrical system asa hole. Remember pipes, clamps, Cheeseboroughs, all get paint and oxidation build up on them. The human body makes a much better/shorter path to ground. Just because the grid is grounded you cannot count on that to reduce your risk of shock. If The students don't know how to build cables, then they need to be shown how. if they are rushing and not doing a proper job of it then they need to be shot. Or at least have the importance of what they are doing impressed upon them. Wiring is something that is done just to make light happen it is a life/safety issue for the public and everyone who walks through the doors of your theatre.
Ok now I'm done.

[Chris15]

Hmm, never heard of these terms "Janus" and "Stinger" in this context. I shall have to do the same as Van and file them in the synonyms file.

Here we just call them extension leads, whatever their length, boring I know.

As far as grounding goes, Van, you are right, I stupidly made an assumption (must have been late at night). Is it not standard practice to run a wire to electrically link the LX Bar to the building's electrical system Earth?

As far as wiring, I am slightly surprised that the school's insurers etc. do not have a major objection to you doing your own wiring. Ignoring that, it would be a good habit to get into the practice of properly testing cables that have been finished before putting them into service. Down here, you are required to do so, not just when they are new, but regularly (every 3 months in most cases) as part of test and tag, which not only tests for basic wiring errors, but also tests the resistance of the earth bond and the insulation resistance as well as other tests for appliances - ask if you want more boring details.

While I understand that you probably are having students build the cables as a learning exercise, perhaps something other than mains would be better for this? Otherwise, keep a close watch and check the wiring thoroughly before the backshells go on - easier to correct mistakes then

Just my thoughts, take em or leave em.

[Van]

Chris, as far as grounding/earthing the grid itself goes, out of the 5 < standard pipe grids > I have installed, none have had a direct tie-in to the grounding/earthing system of the buildings electrical system. To the contrary most are pretty well insulated from anything because of the use of rubber installed around all connetions to reduce noises like squeaks of metal on metal.