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GFI or GFCI limitations


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#1 David Cronin

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Posted 01 June 2009 - 07:19 PM

Hey Guys,
So I have done a little research on GFI's or GFCI (ground fault circuit interrupter). There those outlets designed to add greater level of safety by reducing the risk of electric shock. Most building codes now require that a GFCI outlet be used in wet locations such as bathrooms, kitchens, laundry rooms and outdoors.
Posted Image

The basic idea behind a GFI is it monitors for current imbalance between the hot and neutral wires in a household circuit. When they go off balance the GFI circuit trips, and all the other circuits in that loop trip as well.

Typical gaffers I work with often tell me to avoid these outlets, but have had to use them once or twice when necessary. But I usually use tungsten lights without ballasts...it worked fine.
Would there be any problems if I strike a 1.2k hmi on a gfi?

Has anyone encountered any problems with GFI outlets?

Are small budget location shoots going to be screwed from building code of the future?
But then again, this is LA. Who is really up to code anyway :o .


Best,
Dave
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#2 Richard Andrewski

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Posted 01 June 2009 - 10:11 PM

They're a lot of trouble and require special isolation to use with some kinds of electronic lighting. Here's a link about it:

http://www.reduser.n...ead.php?t=20673

More:

http://www.tvss.net/pq/ballast.htm

and still more:

http://www.physicsfo...p/t-174420.html


I guess if you have an isolation transformer on the input to your fixtures you won't have a problem.
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#3 John Sprung

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Posted 02 June 2009 - 04:13 PM

I guess if you have an isolation transformer on the input to your fixtures you won't have a problem.


If you get a trip with the iso transformer, it'll be from something between the GFCI and the transformer. Note that beyond the transformer, you no longer have GFCI protection. Depending how it's wired, your "hot" and "neutral" there may be floating -- no reference to true earth ground. Be sure to let your sound guy know if you're using iso transformers, just as a courtesy.





-- J.S.
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#4 Salil Sundresh

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Posted 03 June 2009 - 03:41 AM

Hey Guys,
So I have done a little research on GFI's or GFCI (ground fault circuit interrupter). There those outlets designed to add greater level of safety by reducing the risk of electric shock. Most building codes now require that a GFCI outlet be used in wet locations such as bathrooms, kitchens, laundry rooms and outdoors.
Posted Image

The basic idea behind a GFI is it monitors for current imbalance between the hot and neutral wires in a household circuit. When they go off balance the GFI circuit trips, and all the other circuits in that loop trip as well.

Typical gaffers I work with often tell me to avoid these outlets, but have had to use them once or twice when necessary. But I usually use tungsten lights without ballasts...it worked fine.
Would there be any problems if I strike a 1.2k hmi on a gfi?

Has anyone encountered any problems with GFI outlets?

Are small budget location shoots going to be screwed from building code of the future?
But then again, this is LA. Who is really up to code anyway :o .


Best,
Dave

I tried running a 1.2kw Arri fresnel HMI out of a residential bathroom which had a GFI and it tripped pretty quickly. There was nothing else on the 15A circuit.
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#5 John Sprung

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Posted 03 June 2009 - 04:02 AM

I've seen stingers that would trip a GFCI with nothing plugged into them.




-- J.S.
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#6 Kevin Fox

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Posted 08 June 2009 - 02:26 PM

Ditto what John said! Best to avoid GFCIs when possible. It is however a good idea to know WHY they are there and be sure to avoid putting yourself in harms way, since you will no longer have their safety benefit.

Best,

kfox
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#7 Karel Bata

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Posted 09 June 2009 - 06:55 PM

David,

"Typical gaffers I work with often tell me to avoid these outlets,

And you ignored them because...?

but have had to use them once or twice when necessary."

necessary? :huh: Have you been rigging lamp stands in bath tubs full of water or something? :D
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Media Blackout - Custom Cables and AKS

Metropolis Post

FJS International, LLC

Technodolly

Broadcast Solutions Inc

Ritter Battery

Visual Products

Gamma Ray Digital Inc

CineLab

Paralinx LLC

Wooden Camera

CineTape

The Slider

Aerial Filmworks

Rig Wheels Passport