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Ungrounded Arri 575/1200 Ballast


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#1 Doug Brantner

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Posted 23 March 2010 - 12:40 AM

There appears to be a built in safety circuit Arri 575/1200 ballasts that renders them useless if they are not properly grounded. I imagine this is to child-proof them since they're very popular in film school rental houses.

But I've definitely seen larger units (6k and up) work fine with no ground, not that I condone such behavior.

If you find yourself in a location where the circuits aren't grounded (i.e. most of NYC), is there a user-accessible (read: repair-tech accessible) jumper to disable the safety circuit? Or would you have to run your own ground?

Please feel free to PM me, or point me in the direction of the appropriate repair manual. I agree this isn't the safest thing to do and it needn't be plastered on the walls of the internet for all to see. Thanks.
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#2 JD Hartman

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Posted 23 March 2010 - 12:52 PM

Interesting, what model ballast? Work around would be to use a ground lift adpter and tie the ground to the neutral. Or attach the ground lead to the metal wall box (if accessable and if metalic). In most all cases, ground and neutral are tied bonded at the main panel.
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#3 John Sprung

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Posted 23 March 2010 - 12:56 PM

In most all cases, ground and neutral are tied bonded at the main panel.


Yup, that's what the National Electrical Code says to do. Neutral and ground are supposed to be connected to each other at the service entrance, and nowhere else in the building.





-- J.S.
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#4 Doug Brantner

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Posted 23 March 2010 - 02:59 PM

Haha, of course! I forgot the little green tab on the ground lift was actually there for a reason... I guess I'd try to ground it to the outlet box, not sure how I feel about tying ground to neutral.

Not sure what model specifically, but it's the very common Arri 575/1200 model, not DMX. According to what Arri literature I could find, it seems hard-wired and not optional.

Probably faster to properly apply the ground lift (now ground add!) adapter than to field-modify the ballast anyway...

Thank you, gentlemen!
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