Dimmer Switches excess heat

Reply

  #1  
Old 02-25-15, 10:25 PM
Member
Thread Starter
Join Date: Feb 2015
Location: us
Posts: 1
Dimmer Switches excess heat

In my church we have several dimmer switches that controll he main lights in the sanctuary. 2 of the switches are 3 way and control several lights. They both have a toggle type switch on the other side of the sanctuary. Both are overloaded and get very hot during our service. My question is "if I wire 2 dimmers together in series for each of the single dimmers will that split the load so that they will not be overloaded?" If not it seems that a rewiring would need to be done to reduce the number of lights being controlled by each dimmer. That would be an expensive order and one the church cannot afford at this time. The dimmers that are there now are 1000w dimmers and carry 780w each.
 
Sponsored Links
  #2  
Old 02-25-15, 11:57 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 46,091
Welcome to the forums.

You can't connect two dimmers together for one set of lights. If you can't split the circuit up then you may be forced to upgrade the dimmer size to a 1500 watt unit. It'll fit in the same two gang box the 1000 watt dimmer was in.
 
  #3  
Old 02-26-15, 01:37 AM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
Are these two dimmers right next to each other and have any of the cooling fins been removed? 780 watts on a 1,000 watt dimmer should not cause overheating although it may indeed make the dimmer metal parts too hot to touch.

When installing dimmers being run at more than 50% of rated capacity you need to have all cooling fins in place and if at all possible space between dimmers, either a regular switch or simply a blank space. Use the thermosetting (Bakelite) type plastic cover plates rather than the nylon or metal cover plates.
 
  #4  
Old 02-26-15, 05:40 AM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,383
The dimmers that are there now are 1000w dimmers and carry 780w each.
Before doing anything, I am going to suggest you get the model of the dimmers and get a manual for them. Read carefully about ganging the dimmers in the same box and pay special attention to the part about derating the dimmers when ganged or when cooling fins have been removed to get them in the box, like Furd mentioned. Even when operating normally the dimmers will be hot. If after derating the dimmers are still adequate for the loads, I'd further suggest finding a raised, ventilated switch plate. Last resort, replace with 1500 watt rated dimmers like PJ mentioned.
 
  #5  
Old 02-26-15, 07:21 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,502
You could also approach this from the other side by decreasing the wattage of the bulbs, do you use them at 100% brightness? You could try out dimmable CFLs or LEDs, although that wouldn't necessarily be "cheap" depending on which lamps you select.
 
  #6  
Old 02-27-15, 06:01 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,277
A sales rep told me one time that it is normal for a dimmer to be up to 70 degrees above ambient temp.
 
  #7  
Old 02-28-15, 04:29 PM
Gen
Gen is offline
Member
Join Date: Jun 2006
Location: US
Posts: 378
"You can't connect two dimmers together for one set of lights." Usually yes, however Lutron now has switches, wired differently from normal 3 way, that will accomplish this.
 
  #8  
Old 02-28-15, 06:18 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
Gen, I think that you are referring to "master-slave" dimmers to allow dimming of one set of lights from multiple locations. In addition to Lutron, Leviton and other manufacturers have had these for many years.

However, in the initial post kenfrye wanted to use two dimmers in parallel to increase the capacity of the dimming circuit and THAT cannot be done.


Since it has been a few days and kenfrye has not returned I suspect he is another in a long line of one-post wonders.
 
  #9  
Old 02-28-15, 08:13 PM
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,481
"However, in the initial post kenfrye wanted to use two dimmers in parallel to increase the capacity of the dimming circuit and THAT cannot be done"

Why can't it be done? Theoretically, you'd be sharing the load between two dimmers thereby decreasing the load on each. I'm not implying it is "okay", but rather asking for my own education.
 
  #10  
Old 02-28-15, 08:19 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,043
Dimmer switches are no longer simple resistors. They are electronic circuits that cut the power off for a very brief time at the lowest point of the sine wave where the polarity shifts.
 
  #11  
Old 02-28-15, 09:27 PM
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,481
I was thinking of the older resistive type not the switching type, but even then, you're splitting the current between two parallel branches are you not?
 
  #12  
Old 02-28-15, 09:33 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
Mossman, think about it. If you had two dimmers then you would have to move the knobs in exact synchronization or you would upset the sharing of the load. In addition, no two consumer grade dimmers are exactly alike so even if you could "gang" the knobs there is NO guarantee that the two dimmers would track electrically.

They DO make stage dimmers that allow for multiple dimmers to be adjusted from one controller but the cost would be prohibitive in this instance.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes