Retrofitting dimmer to house lights

[samchurchill]

Hi all,

 

The house lights in our venue have switches in the most inconvenient place, where you can't see what's happening on stage. Some of them are arc lights, which I know we can't really do anything about, but we'll often do evening events just using the standard ceiling mounted lights (domestic 100W bulbs) which are around the whole room, underneath the balcony. I'd really love to get control of these from the lighting console.

 

However, we mustn't lose the ability for anyone to just come to the normal switches and switch them on. I have therefore come up with the idea of putting in a dimmer pack in parallel with the normal switches, which would mean that the lights could be powered from either. (I know a dimmer pack with built-in override faders would do the job, but I'm thinking it'll need to be an architectural dimmer pack to fit into the required space. It also might be a bit too complex for some people who will just need the switches that have worked for 20 years to still work!)

 

Is the parallel switch idea possible/safe? Will there be a problem with the dimmer pack essentially being subjected to 240v from the "wrong" side when the normal light switch is on?

 

Any advice greatly appreciated.

 

Sam

[vinntec]

In our small theatre the power goes through the houselights switch THEN through an AlphaPack dimmer (so in series) which means that both have to be on for the houselights to be on. For day to day use, the channel is left full on from the lighting position (separate to the desk) meaning that the switch can be used as normal for rehearsals etc. In this case the AlphaPack is analogue so the operators control is a simple slider, but it could also be a DMX dimmer with local control (assuming you don't want your desk on all the time).

 

For productions, we used to live with this as controlling the dimmer would control the houselights - unless you had forgotten to make sure the switch was down in the auditorium in which case you had no control! So a "Performance" switch was added which cut the switch out of the equation regardless of how it was set, which the LX operator sets as part of the pre-show checks.

 

This doesn't fit your situation exactly but might give some ideas of other ways of doing it?

 

Peter

[maeterlinck]

I would use a dimmer with DMX and analogue control in htp. Use the swithces to provide the full 10volts to the analogue input. DMX from the lx desk. An old betapack or similar would do the job nicely - I'm guessing you're on a budget.

Remember you'll need to have a qualified sparks do the non plug connections and sign it off.

 

edit to make more sense...

[Brian]

Is the parallel switch idea possible/safe?

It depends entirely on which dimmer pack.

 

Don't underestimate your users ability to use a small amount of technology. I've fitted several systems where the houselights can be DMX controlled as well as over-ridden. I use Anytronic's dimmer packs which have both 0-10v inputs and DMX inputs. A simple pot to offer local control is all that is needed, plus it gives users the ability to dim the houselights.

[samchurchill]

Thanks all.

 

Unfortunately we have to pack away the lighting console after every event, so we can't do the idea of having them in series.

 

The Anytronics kit looks good - I might look to see whether we can stretch to that as, as you guessed, we're on a bit of a budget.

 

I'll have a bit more of a look at quite how much space is available in the cupboard where it needs to go. This would a bit of an interim solution, hence why space etc is so tight.

 

Sam

[PaulDF]

I did something similar which included having the light switches operating SPDT relays, if the relays are de-energized the house lights are connected to the dimmer pack, when the relays are energized the house lights are connected to 230v.

I have a key switch (bit pointless really as the key gets left in) which in one position provides power to the light switches and in the other provides power to the dimmer pack.

I think I have an NJD 4 channel dimmer so is hard wired.

[electronicsuk]

Having been faced with a similar dilemma working with a local cinema and theatre currently undergoing refurbishment, I spent a lot of time comparing the different solutions on the market that allow both local and DMX control of house lights, and chose the Anytronics kit in the end. Admittedly our requirements were probably a bit more complicated owing to the need to control some LED uplighting and the need for dimming and presets without a lighting desk, but it seems to me like If you only need a single channel of dimming control then you could probably use their Pro-Dim single channel pack (it takes DMX and 0-10v) along with matching outstation.

 

I haven't seen pricing on the single channel kit, but I suspect you'd get a complete system for about £250. We paid just a little over £550 for a 4 channel installation dimmer (channels can be set as zero-cross switching for non-dimming loads), a 10 channel/5 preset outstation and a 32 channel interface card. You'd easily get away with the 8 channel card if all you need to control is the 4 channel dimmer, but the 32 channel card costs about £20 more and you can connect and control some external DMX channels.

 

Your original idea of using parallel switches could make made to work quite well using 2-way switches to select between dimmer live and a permanent live feed, though you'd still need common neutrals. Definitely wouldn't recommend it unless your dimmer pack is hardwired and you can pick up the permanent live feed from the same supply as the dimmer.

[Brian]

@samchurchill

 

Keep an eye out on eBay. Anytronic DP405s (4 channels of 5A) come up quite regularly and are as tough as old boots.

[dbuckley]

Another option is the Zero88 Chilli, available asa small as a four pack, can do DMX and buttons to preset states.

[itiba]

Your original idea of using parallel switches could make made to work quite well using 2-way switches to select between dimmer live and a permanent live feed, though you'd still need common neutrals. Definitely wouldn't recommend it unless your dimmer pack is hardwired and you can pick up the permanent live feed from the same supply as the dimmer.

 

I'd be quite cautious about using a standard domestic switch as it wouldn't necessarily be a 'break-before-make' switch and you could either end up inadvertently crossing two phases (which would be bad) or back feeding an otherwise isolated circuit and possibly in 5, 10, 15 years electrocuting someone! I'd recommend something like a 'DPDT Centre Off Switch' but using the above 10v dimmer input idea would work much better :)

[Ashley R]

I do know the LSC Redback dimmers, and a few other LSC Dimmers have got some fancy stuff built in, so you can have local control, or control from the console.

[Richard P-W]

We have a setup involving an Anytronics pro-dim which gets an analogue feed from the demux and then a box of contactors to allow switching between the dimmer and manual light switches in the auditorium. Mostly it works but occasionally gets in a knot and has smoked one Anytronics unit in the last 10 years.

I'm ripping it all out soon as we don't have a schematic and I'm going to put a rotary pot in a box for manual control of the dimmer from the auditorium - with a relay switched by a 2nd analogue channel to choose between the pot and the 10V from the demux. That last bit means we can inhibit the manual control when the desk is running and it defaults back to manual when the desk is powered down.

[Matt Riley]

What about a dimmer with 0-10@v analogue as well as DMX control. You could then use the existing switches to control the dimmer using a simple 10v supply which sends 10v when the switch is on and this controls the dimmer. Then you could plug in DMX into the other input and you have your solution. This would be htp so you could turn the 10v supply on and off from the lighting desk position to isolate the switches ?

[Gerry]

What about a dimmer with 0-10@v analogue as well as DMX control.

Already suggested in posts nos 3 and 4.

Cheers

Gerry

[jonic222]

In one of the theatre I worked in we installed a 4 channel zero88 chilli which was wired in series with the switches in the auditorium. We set the chillis to go to 100% if they lose DMX, so at the end of the night when the lighting desk is switched off then the switches have full control over the house lights. It also means that if we lose power to a lighting desk or have other problems we automatically get house lights.