Dimmer Temperature


We have 2 Sensor Racks for a total of ~192 dimmers at work. One of the racks keeps having airflow warnings. Both racks seem to be getting very hot, even when nothing is running (~90º with nothing on). If we open up the dimmer room (which has ventalation problems, plus 2 large power iso's in it), and open the rack doors, we can get the dimmers down to 82º. What is the safe range of temperatures for Sensor Dimmers?



Senior Team
Senior Team
Premium Member
how long have the dimmers been in place, and when was the last time all of the dimmers where taken out and blown off and the cabinet was vaccumed out?.... also are all of the racks completly full... (with 192 they should be...) i believe that the dimmers are suppost to run with the door shut to keep the dimmers clean.... 82 is fine as long as your not getting an overtemp... give etc a call and ask them for the exact temp.... also you might want to look into getting an AC put in your dimmer closet... they make some that are self contained and have a hot air tube that you can either stick in the plenum or run outside....


Well-Known Member
At every place I have worked the ETC dimmers have given off the airflow problem. A reset makes the message go away for a while but does not fix the issue, if one exists. The rack is ok as long as the ambient temp does not go over 104 F, the 'no airflow' means insufficient airflow is detected and the manual says to check the fan and filter for obstructions.


Active Member

I'd say definately give ETC a call, they'll probably be able to help you out. In the mean time it might be a good idea to do a thorough cleaning of the rack. That means vaccuuming out the dimmers (VERY important to use a STATIC FREE vaccuum for this) and vacuuming out the actual filter on the door of the rack. Make sure you don't have anything on top of the rack or anywhere blocking the air flow.

Just my 2-cents.



Active Member
One thing our installer told us to do when he was giving us the preliminary training on the system, was take the CEM module out and dust off the board every once in a while. He pointed out a little IC on there that measures the airflow/temperature; he said if it gets too dusty, it will set off airflow alarms. I'd say get that CEM module out of there and dust it off **carefully**. Also, when you pull out your CEM, make sure that nobody is going to be bothered by the lights being off...everything in that dimmer rack will immediately be shut off when you remove the CEM. Even the fan and blue beacon light go off when you yank it...it's pretty weird standing there with your usually humming away dimmer rack dead as a doornail.

When you remove the dimmers to clean them, be sure to shut off the breakers before you yank them. It's OK to yank dimmers from a hot rack, but just don't stick your hand in there, as you will get a deadly 208V zap. If you're doing the whole rack, I'd recommend shutting the whole system down first.

Clean out your air filters as well, they just pop right out of the inside of the rack door. Also a few more things to remember, every empty slot must have an AFM (Air Flow Module) installed to seal up the hole. Without it air will seek the path of least resistance, which would be the hole. It would probably be a good idea to vacuum out your fan as well, but be sure you turn off power before you go tooling around in the rack without dimmers installed. Keep the door closed when you're not working on the rack, or the filters in the door won't do you any good. Check for any air leaks around conduits and onther openings, and if you find any, seal them up. Our rack was sealed in various places by that expanding spray foam stuff. Does your rack's fan vent into the room, or does it go into a duct? Be sure the duct isn't blocked if one is installed. Also make sure something wasn't placed on top of the fan. Our old Electro-Controls dimmer cabinet was infamous for burning up when the fans were blocked. It almost burned the place down twice when some idiot put stuff in the electric room in front of the vents.

Is that 90ºF or ºC? 90ºF shouldn't be a problem, but 90ºC is definately too hot. I know my dimmers, D20 modules in an SR48 rack, or at least their SCR heat sinks, don't get hot to the touch even when dimming 2250 watts all day on our cyc light circuits.

Hope it all comes out OK. ETC is famous for their good support, so if you can't get it fixed, and it was installed or approved by an ETC certified rep, then you shouldn't have any problems getting ETC to give you some advice.

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