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Metal Halide Light Circuit #36669 04/12/04 10:14 AM
Joined: Apr 2004
Posts: 5
A
AutomationMan Offline OP
Junior Member
I do controls and have almost never done any lighting or power distribution work, so excuse my ignorance.

I need to put a few light fixtures in my shop and can get a few 400Watt Metal Halide, multi tap fixtures real cheap. I know that I don't want to use these on 120, but I am curious about what I will need to do to switch them on 240. Will I have to use a contactor and then switch the contactor? Surely there is no contactor in the fixture itself.

I guess I could just switch them on and off with the circuit breaker, but I really don't want to do that.

Hopefully I can return the favor if any of you have controls questions.

Thanks for any help you can offer.

Have a great day,
Doc


Doc
Work Gear for Electricians and the Trades
Re: Metal Halide Light Circuit #36670 04/12/04 10:34 AM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline
Moderator
You can switch them off of a standard switch if you would like. If you switch them with the breaker, make sure your breaker says "HID"...not "SWD".


Ryan Jackson,
Salt Lake City
Re: Metal Halide Light Circuit #36671 04/12/04 10:48 AM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
A standard 2 pole switch. [Linked Image]

A 400 watt fixture run at 240 will draw about 2 amps.

I would not put more than 5 of these on a 15 amp circuit or 6 on a 20 amp circuit.

If by chance you try a hot restart they will, many times draw higher amperage and will trip the breaker of a maxed out circuit.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Metal Halide Light Circuit #36672 04/12/04 10:51 AM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline
Moderator
Good catch on the two pole switch Bob.

Also, if you put them on a 120V circuit, be careful about how you load them. HID lighting is non-linear, so you will want to consider the effects of harmonices on a nuetral...even more reason to keep only a few of them on one circuit.


Ryan Jackson,
Salt Lake City
Re: Metal Halide Light Circuit #36673 04/12/04 10:59 AM
Joined: Apr 2004
Posts: 5
A
AutomationMan Offline OP
Junior Member
Thanks guys for the quick and very useful replies.

As often happens, answers, beget more questions. If I were to only have two of these on a circuit where sufficient current capacity remains for other service, will there be any kind of concern for interference of any kind? Example, would there be any ill effects with instrumentation electronics on the same circuit, or an electronic 3 phase to Single phase converter on the same circuit?

Thanks a million,
Doc


Doc
Re: Metal Halide Light Circuit #36674 04/12/04 07:57 PM
Joined: Dec 2003
Posts: 886
H
hbiss Offline
Member
They are no more noisy than flourescents. I would opt for separate circuits though if for no other reason than not losing your lighting if something else trips the breaker.

-Hal

Re: Metal Halide Light Circuit #36675 04/13/04 03:27 AM
Joined: Oct 2000
Posts: 2,721
Scott35 Online Happy
Broom Pusher and
Member
The suggestion of using the 2 Pole Switch is great!
Be sure to use a 2 Pole Switch, not just a Single Pole Switch - since the Ballasts' will have 240 VAC Input.
Using only a 1 Pole Switch will leave a 120 VAC Ungrounded Circuit live at the Ballast, unless the 2 Pole Circuit Breaker is thrown to the Off position.

Best not to Switch from the Circuit Breaker - as this relies on you traveling to the Panelboard each time to throw the breaker.
Also, your make / type of Panelboard may not have Circuit Breaker Frames which are Switch rated (SWD).
Repeated throws of the Breaker's handle results in wearing out the device prematurely.

No need to use a Contactor, unless you plan to control them via low voltage means.
You could use a Contactor - even if the Control Circuit will be 120 or 240 VAC, but it's kind of redundant!

As far as noise, you may experience some noise when the Lamps first start (initial arc), and possibly when trying to restrike.

There will be a few levels of Harmonic Distortion throughout the operation - which is bound to happen with these L-C devices ("L-C" being Inductive - Capacitive, not Line to Common!).

Filter the inputs of sensitive equipment with typical AC Line Filters - PI setups with Inductors on both Input Lines.

Keep the HID equipment within a metallic enclosure, and be sure it's bonded with a solid EGC. This will reduce a lot of free floating noise in the close vicinity.

Should not have too much trouble with noise, but then again when circuits and elements resonate, funny things happen!
When and if they will resonate is a crap shoot!

Feel free to ask questions, as my reply only carries brief and basic data!
Beware, I can make this sound like Rocket Science!!!
[Linked Image]

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: Metal Halide Light Circuit #36676 04/13/04 08:56 AM
Joined: Aug 2003
Posts: 1,374
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Ryan_J Offline
Moderator
Quote
Also, your make / type of Panelboard may not have Circuit Breaker Frames which are Switch rated (SWD).

Scott: I think the SWD breakers would be a violation. For this type of lighting I think it needs to be "HID" breakers.


Ryan Jackson,
Salt Lake City
Re: Metal Halide Light Circuit #36677 04/13/04 11:12 AM
Joined: Nov 2000
Posts: 2,148
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resqcapt19 Offline
Member
While I agree, that a two pole switch should be used, what code section requires the use of a two pole switch?
Don


Don(resqcapt19)
Re: Metal Halide Light Circuit #36678 04/13/04 01:21 PM
Joined: Aug 2003
Posts: 1,374
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Ryan_J Offline
Moderator
Don: Wouldn't 240.20(B) apply?

EDIT: Strike that, it doesn't apply. Sorry

[This message has been edited by Ryan_J (edited 04-13-2004).]


Ryan Jackson,
Salt Lake City
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