Flickering Practicals and Portable Dimmers

[SunbirdTD]

I have two-wire practicals that I am plugging into portable dimmers. They flicker unless they are up at 80%. I am so tired right now and up against an opening this Thursday. What is the issue and how do I fix it?

 

[dantemclean]

I have two-wire practicals that I am plugging into portable dimmers. They flicker unless they are up at 80%. I am so tired right now and up against an opening this Thursday. What is the issue and how do I fix it?

The dimmers need to have more load on them in order to dim the practicals properly. Add a "ghost lamp" someplace on the circuit (backstage or in the wings where you can't see it). In the past, I have loaded up dimmers that were powering X-Mas Lights using a desk lamp (or several) with 60 watt bulbs in them. Otherwise, stick a PAR or something on that circuit, along with your practicals.

 

[SunbirdTD]

The dimmers need to have more load on them in order to dim the practicals properly. Add a "ghost lamp" someplace on the circuit (backstage or in the wings where you can't see it). In the past, I have loaded up dimmers that were powering X-Mas Lights using a desk lamp (or several) with 60 watt bulbs in them. Otherwise, stick a PAR or something on that circuit, along with your practicals.

Oh, thank-you! That makes sense. Each dimmer will have a 450w fresnel and two practicals, I just hadn't added the fresnels yet. I can sleep easier. Thanks!

 

[RonHebbard]

Oh, thank-you! That makes sense. Each dimmer will have a 450w fresnel and two practicals, I just hadn't added the fresnels yet. I can sleep easier. Thanks!

@SunbirdTD You'll find using a ghost load will normally allow you to dim small neon signs if you're ever lighting a production set in a seedy bar. As long as you don't exceed the wattage rating of your dimmer, other devices can be used for ghost loads such as heating pads (with their low, medium and high settings being used to provide varying amounts of load WITHOUT producing light). Toasters, electric frying pans and hot plates can be used for dummy loads as well but nothing with any appreciable amount of electronics such as microwaves. Bear in mind NOT to exceed the wattage ratings of your dimmers.
Toodleoo!
Ron Hebbard (I guess it's your night to hear from Canada.)

 

[dantemclean]

Coffee Maker? LOL

Dante.

 

[RonHebbard]

Coffee Maker?
Dante.

@dantemclean and @SunbirdTD Sure, if it's a purely resistive load with no fancy electronics, timers, etcetera. Personally, back in the 1960's with a resistive board, I used a single element hot plate cooking appliance for a dummy load on one dimmer and a two element hot plate with only one element switched on as the dummy load on a second dimmer. The board was a British built Strand 8 dimmer resistance board with each dimmer rated for 2 to 3 Kw. I had LARGE signage on the hot plates to remind passersby that they were HOT since they didn't glow red if / when the dimmers were set at ~ 30% or less. Passing cast often tried to set personal items on any handy horizontal surface while they were on stage. I vaguely recall using an electric kettle, with water in it of course, as a dummy load on a larger resistive dimmer more than once. If you remember saturable core dimmers, such as Strand's system LC, we used to employ dummy loads with those as well as they wouldn't dim at all with very small loads such as table lamps and / or wall sconces.
EDIT: @dantemclean and @SunbirdTD Perhaps it's worth noting, if / when you opt to use an electric kettle for a dummy load, BE CERTAIN TO PUT WATER IN IT, a kettle without water will not dissipate heat safely, it's exactly like boiling a kettle dry. Yeah, really. I wouldn't kid anyone about a potential fire hazard.
Toodleoo!
Ron Hebbard