Lutron Grafik eye

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laidman

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We have a lutron grx3106 Grafik Eye dimming system controling 8 HP-4 4000W power boosters. The system is operating properly but the transformer and breakers used to feed the system are over heating with only 10.5 amps per circuit. Using a circuit analizer we are showing large amounts of harmonics third fifth and seventh. I believe this is the cause of the over heating.

When it was installed they used a common nuetral for every 3 circuits. I'm pretty sure that this is the cause of the problem. This would mean a complete rewire as the conduits are not large enough to add the additional neutrals.

I talked to Lutron and after being switched to for different techs the one that was supposed to have the knowledge to answer me asked what a harmonic was. Has anyone had this situation and has a solution.

Thanx
 
Re: Lutron Grafik eye

I've installed the grafik eye system and never had a problem.
We pulled seperate neutrals for each circut.

Do you have an oversized neutral?

Also, In the past, I found Lutron's techs to be very knowledgeable about their systems.
 
Re: Lutron Grafik eye

Don't most electronic dimmers say you have to have separate neutrals? I thought you could get strange things by sharing a neutral on a dimmer (like the lights changing level by themselves)?
 
Re: Lutron Grafik eye

I could be completly wrong, but it just doesn't sound right to me that a common neutral would cause harmonics. The neutral is going be common some place no matter how it's wired. Is it possible that something unrelated is the source.
 
Re: Lutron Grafik eye

I found out that the dimming system was decided on afer most of the wiring was completed and the contractor that installed it was not aware of the need for separate neutrals. separate neutrals back to the panel prevents harmonics from all three circuits from showing up ont one neutral.

By the way most Lutron techs arevery knowedgable about their products. I don't know what happened to the one I got to talk to.

New question:
would seperate conduits for each circuit be better than running 3 neutrals and three hots in the same conduit?

[ February 23, 2005, 11:19 AM: Message edited by: laidman ]
 
Re: Lutron Grafik eye

Originally posted by laidman:

New question:
would seperate conduits for each circuit be better than running 3 neutrals and three hots in the same conduit?
Click to expand...
You might have to derate your conductors per the Table shown on 310.15(B)(2)(a). Also look at 310.15(4)(a,b,c) for Neutral conductor requirements.
 
Re: Lutron Grafik eye

So, pulling separate neutrals would probably alleviate the heating on the branch circuit breakers, but I think you would still get heating on the transformer. Is there another solution that would solve all of your heating problems? Something cheaper than possibly new conduits and wiring? Not sure if there is a better solution...just a thought. :)
 
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