crazy temp fluctuations possibly caused by A4 ballast

[Travis]

Hi Curt, I spoke with you on the phone on Monday evening regarding problems with my temp probe readings. To refresh your memory, my chiller is on the same circuit as my AC Pro. My chiller shorted out the GFCI receptacle it was plugged into. It didn't trip it, it completely shorted it out to the point where I no longer have any current at the receptacle. The next morning was the first time I noticed the rapidly fluctuating temp readings, which I've never had before (everything has been running for almost a year). This was on Saturday. I had an extra temp probe on hand so I hooked it up and all was fine. Then on Monday the same thing happened again. I got a page on my cell while I was at work due to an alarm temp condition. When I went home I realized that the temp reading was fluctuating all over the place. So I switched back to the original probe I was using and all seemed well for an hour or so. Then the readings started going crazy again. I called you and talked to you about it that evening. We came to the conclusion that it was most likely not from the chiller shorting out the receptacle on the same circuit, but rather the URI A4 (made by IceCap) electronic VHO ballast that I installed about a month ago. Even though the ballast is on a completely different circuit and I have had 0 issues until now. You recommended that I set my data log interval to 1 minute and see what happens.

Well, it has stopped completely since I talked to you. I've done nothing different. Didn't move any wiring nor did I stop using the A4 ballast. Is it normal for electonic ballast interferences to be so random like this? What can be done to remedy the situation? I'm sure the obvious answer is to ditch the new ballast but I really do want to run VHO actinics to supplement my MH's so I won't do that unless it is a last resort. Would one of the noise filters fix a problem like this?

PS. I did check my past data logs and noticed that the 2 days that I did have the problems, it was while my VHO's were on. But I still don't feel it is enough info to completely blame the A4 ballast "yet".

BTW, I have no other electronic ballasts running on any of my tanks. The rest of my ballasts are PFO HQI MH ballasts.

 

[clp]

I would expect that the interference when present to consistently cause the same problem, given nothing else has changed. Something else must be going on to explain the problem, but I don't know what it is.
If it is the ballast, make sure that the hood as grounded as this will minimize the amount of radiate EMI which may interfere with the temp probe reading.

Curt

 

[Travis]

All of my lighting ballasts are grounded. Do I need to ground my hood also?

This is my hood, which houses 3 MH's and and 2 160w VHO's (not in picture). All of the MH ballasts are located remotely (about 4 feet away). The A4 VHO ballast is just sitting on top of the hood.

<img src=http://sio.midco.net/cdshelton/website/page10/canopy/8-3-040012.JPG>

IF it is the A4 ballast causing the problems would a noise filter or DC4 fix it?

 

[clp]

Yes, I'd recommend grounding the hood. A noise filter would not help as I suspect that the RF energy is radiate through the air not through the power lines. You also might want to try an RF choke on the ballast cords - radio shack sells them.

Curt

 

[Travis]

What does RF stand for?

 

[clp]

Radio Frequency. Bring an AM radio into the room with the ballast. If the radio receives a lot static when the ballast is on then the it emits a lot of RF energy.

Curt

 

[Member No. 1]

http://hps.org/hpspublications/articles/rfradiation.html
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