LED par cans powered from dimmers?

[grantr22]

Hi all.

 

A venue I use regularly has just had a new rig installed. Visiting for a look a day or 2 before completion I'm very surprised to see that the contractor has installed LED par cans to which 15A plugs have been fitted, and as one would assume that every 15A socket on each IWB is fed from a dimmer, they are plugged into dimmers as opposed to them having 13A plugs on and connected to a hard supply which is what I would have expected.

 

There is a DMX daisy chain running through each one so they will "work" as long as they're addressed and the desk is set up accordingly, but from experience I'm sure the mains supply method is unusual and the likelihood of varying / dimming the supply to an LED fixture isn't going to do any of the hardware any good? Can it reasonably be expected that the rig / desk is used with the appropriate channels permanently at 100%, for its lifetime and in every scene including blackouts? The dimmers are hard-wired so the IWB sockets can't be patched to hard power. Or, if the appropriate dimmer channels have been set internally via dip-switches to supply hard power, this would be a waste of dimmers and therefore an unnecessary financial cost for the venue?

 

The rig isn't commissioned yet so I've not been able to use it, in other words I've concluded what I've described here from standing on the stage and looking up with a torch. So in fairness I might be jumping the gun and the answer is yet to be revealed - I only doubt myself here because the contractor is experienced and has a good reputation locally. However from what I can see I think I may need to make challenges in support of the venue, but before I do I'd appreciate some views. Many thanks.

[Brian]

...as one would assume that every 15A socket on each IWB is fed from a dimmer...The rig isn't commissioned yet...I might be jumping the gun and the answer is yet to be revealed...

I think you've answered your own question.

 

But, with the later generation of LED cans which use a SMPSU rather than having a 50Hz transformer in them, there is every chance they will run quite happily on a dimmer fed circuit. YMMV.

[adam2]

Agree it sounds a bit like a mistake to me !

Somone has heard that all theatre lights need to be dimmable and should therefore be fitted with 15 amp plugs !

 

Modern dimmers and modern switched mode power supplies will probably tolerate each other, but it would be unwise to count on this, and as you point out it is also a waster of dimmer circuits.

 

I suggest that the venue have an electrician install some undimmed sockets, either 16 amp (first choice) or 13 amp (second choice)

These should be switched from near the lighting desk. No remote control or other complication is needed, just some 20 amp switches. Under normal conditions these outlets can be left turned on, with the LED lantern controlled via DMX.

Switches are however desireable for 2 reasons, firstly a defective LED fixture might "stick" on, and being able to turn the power off would be preferable to unwanted light for the rest of the show. Secondly, these non dimmed outlets might be used for other purposes including Christmas lights, mirror ball rotators, fluorescent lighting and other items without DMX control, such will need readily available switches.

 

D0m3stic type 13 amp outlets find little favour in proper theatre, with 16 amp ceeform being prefered for non dimmed circuits.

They do however have the merit that a lot of low end kit comes with 13 amp plugs. Many LED fixtures have IEC inlets and matching leads with 13 amp plugs are a low price commodity.

The main perceived disadvantage of 13 amp plugs is that the fuse in the plug might blow, high up and not easy to get to. IME this is more theoretical than actual, and very seldom happens.

 

If money permits I would instal both 13 amp and 16 amp outlets for hard or non dimmed power.

That will allow use of hired kit that probably has 16 amp plugs, and d0m3stic or disco tat with 13 amp plugs.

[grantr22]

...as one would assume that every 15A socket on each IWB is fed from a dimmer...The rig isn't commissioned yet...I might be jumping the gun and the answer is yet to be revealed...

I think you've answered your own question.

 

But, with the later generation of LED cans which use a SMPSU rather than having a 50Hz transformer in them, there is every chance they will run quite happily on a dimmer fed circuit. YMMV.

 

Hi Brian,

 

Thanks for your reply, just to clarify some of my assumption on all 15A sockets being dimmers - this is from experience and from the rig having 48 dimmer channels and 40* sockets on all the IWBs (yes, that's unusual too...) so that would suggest that the 8x 15A sockets providing power to the 8 LEDs are not hard power feeds over and above the dimmer-fed sockets. Although the rig wasn't up and running when I was looking there are no more IWBs or soca boxes waiting to be installed and the handover day is today.

 

*42 if you include 2x 13A on the cyc bar for LED battens, this adds a little bit of weight to the theory of some dimmers being configured in 100% mode, perhaps to utilise the breaker as a switch / instead of installing separate switches and breakers.

[WiLL]

I think it's fair to say that fitting 15A plugs to LED fixtures isn't necessarily 'wrong' but it is certainly unusual. As indeed any set-up that required said fixtures to be plugged into a dimmed supply would be unusual. Many dimmers can have a channel set to emulate non-dimmed power but from the people I've spoken to it is not a perfect science, and it is far simpler to simply install some hot-power sockets as required (and then frees up a dimmer channel), you wouldn't need many for LED pars anyway as most reputable makes can daisy-chain power from one fixture to the next as they do with DMX. I think overall any set-up which requires the desk to behave in a certain way and the dimmers to behave in a certain way in order to protect these fixtures power supplies is a set-up which is certainly walking a tight-rope of risks. Particularly if the venue sees a fair amount of turn-around, maybe by visiting crews, cassies or similar who may not know the set-ups particular demands and decide to just unplug a fixture from that socket because the lead on the profile they just rigged can only reach that socket and then they replug the LED par into a different socket. Then that LED par is given a dimmed power supply and throws a hissy fit ( a maybe a sparking fit). In theatre simplicity is normally the best option, give crews what they expect to find, that is 16A ceeforms for non-dim units and 15A for dimmable ones. Over complicating a situation can only eventually lead to confusion.

 

EDIT: P.S. I've just remembered that in actual fact some of my non-dim units have 15A plugs on, but this is because this way I only need my large stock of 15A TRS extensions to get power to where I need, along with some 15A socket to 16A plug short converters. I'm slowly building up a stock of 16A extensions and when I feel I have reached the right amount I will eventually convert those fixtures back to 16A. Maybe this the install plan for these units too?

[ianknight]

Unless of course the dimmers connected to the IWB's are Zero88 Chilli's with the Chilli Relay cards fitted.

 

It is unusual to use 15a connectors for 'hard' power but not unheard of.

[grantr22]

I think it's fair to say that fitting 15A plugs to LED fixtures isn't necessarily 'wrong' but it is certainly unusual. As indeed any set-up that required said fixtures to be plugged into a dimmed supply would be unusual. Many dimmers can have a channel set to emulate non-dimmed power but from the people I've spoken to it is not a perfect science, and it is far simpler to simply install some hot-power sockets as required (and then frees up a dimmer channel), you wouldn't need many for LED pars anyway as most reputable makes can daisy-chain power from one fixture to the next as they do with DMX. I think overall any set-up which requires the desk to behave in a certain way and the dimmers to behave in a certain way in order to protect these fixtures power supplies is a set-up which is certainly walking a tight-rope of risks. Particularly if the venue sees a fair amount of turn-around, maybe by visiting crews, cassies or similar who may not know the set-ups particular demands and decide to just unplug a fixture from that socket because the lead on the profile they just rigged can only reach that socket and then they replug the LED par into a different socket. Then that LED par is given a dimmed power supply and throws a hissy fit ( a maybe a sparking fit). In theatre simplicity is normally the best option, give crews what they expect to find, that is 16A ceeforms for non-dim units and 15A for dimmable ones. Over complicating a situation can only eventually lead to confusion.

 

EDIT: P.S. I've just remembered that in actual fact some of my non-dim units have 15A plugs on, but this is because this way I only need my large stock of 15A TRS extensions to get power to where I need, along with some 15A socket to 16A plug short converters. I'm slowly building up a stock of 16A extensions and when I feel I have reached the right amount I will eventually convert those fixtures back to 16A. Maybe this the install plan for these units too?

 

Hello Will, I agree with everything in your first paragraph thank-you. With regard to your edit, a fair point to raise thanks again but this isn't the case at this venue.

 

Unless of course the dimmers connected to the IWB's are Zero88 Chilli's with the Chilli Relay cards fitted.

 

It is unusual to use 15a connectors for 'hard' power but not unheard of.

 

Hello Ian, thanks for your comments, the dimmers are Anytronics Contractor 24 x2. EDIT - which I see are marketed as "dimmer / switching packs"

 

Agree it sounds a bit like a mistake to me !

Somone has heard that all theatre lights need to be dimmable and should therefore be fitted with 15 amp plugs !

 

Modern dimmers and modern switched mode power supplies will probably tolerate each other, but it would be unwise to count on this, and as you point out it is also a waster of dimmer circuits.

 

I suggest that the venue have an electrician install some undimmed sockets, either 16 amp (first choice) or 13 amp (second choice)

These should be switched from near the lighting desk. No remote control or other complication is needed, just some 20 amp switches. Under normal conditions these outlets can be left turned on, with the LED lantern controlled via DMX.

Switches are however desireable for 2 reasons, firstly a defective LED fixture might "stick" on, and being able to turn the power off would be preferable to unwanted light for the rest of the show. Secondly, these non dimmed outlets might be used for other purposes including Christmas lights, mirror ball rotators, fluorescent lighting and other items without DMX control, such will need readily available switches.

 

D0m3stic type 13 amp outlets find little favour in proper theatre, with 16 amp ceeform being prefered for non dimmed circuits.

They do however have the merit that a lot of low end kit comes with 13 amp plugs. Many LED fixtures have IEC inlets and matching leads with 13 amp plugs are a low price commodity.

The main perceived disadvantage of 13 amp plugs is that the fuse in the plug might blow, high up and not easy to get to. IME this is more theoretical than actual, and very seldom happens.

 

If money permits I would instal both 13 amp and 16 amp outlets for hard or non dimmed power.

That will allow use of hired kit that probably has 16 amp plugs, and d0m3stic or disco tat with 13 amp plugs.

 

Hi Adam, thanks for your comments and suggestions.

[Shez]

It is unusual to use 15a connectors for 'hard' power but not unheard of.

I'm not sure that it's that unusual. Standardising on a 15A plug infrastructure simplifies cable stock significantly - all your soca / lectri break ins / outs can be 15s as well as all the TRS. I'm thinking particularly of venues where there aren't dedicated LX bars and so multis are always run to whichever bars are used for lanterns. Wiring up bars with a mixture of dimmed and non-dimmed fixtures means lots of adadpters one way or the other otherwise.

One of my venues does exactly this - dimmers are ETC Sensors so any 15A outlet can be turned in to a non-dim. As long as you follow standard practice of powering up the non-dims first, it doesn't cause any problems.

[timsabre]

Strange flickery flashy problems can occur with dimmers set to "non-dim" mode when they are set to 0% to turn off power to hard-power devices.

 

There is usually a small leakage current through a dimmer, if the device has a switch mode power supply (e.g. LED pars) this gradually charges up the device until it powers up, just for a moment, then it uses up all the charge and goes off again.

 

If the dimmer is set to 100% on and just used to feed power to the device then this is not a problem. However if it is used for isolation, but the dimmers stay powered on, then weird stuff can happen. Seen it in a few installs where the venue was hoping to leave the dimmers on 24/7 and control power with the DMX signal.

 

This is why some dimmer manufacturers offer relay modules to replace the dimmer modules.

[Barney]

Unless of course the dimmers connected to the IWB's are Zero88 Chilli's with the Chilli Relay cards fitted.

 

It is unusual to use 15a connectors for 'hard' power but not unheard of.

 

...Or the updated ADB Eurorack 60 DimSwitch, where any circuit can be either in dimmer mode or in switched (true Solid State Relay) mode. ;)

 

FWIW: I've had hired-in kit in the past that's needed hard power, and it has been supplied fitted with a 15A connector on captive cable (particularly UV cannons, if I remember correctly).

 

 

Barney

 

 

Edit:

{snip} the dimmers are Anytronics Contractor 24 x2 {/snip}

Oh!

[TomHoward]

I'm only repeating what's been said here but can it be confirmed that the 15A sockets are dimmed and are not switchable hard power?

 

All our hard power is on 15A sockets around the venue, and there is a large bank of switches in the control room. As mentioned this simplifies cabling, although you do have to be aware of what you're plugging into, and it does cause people to believe there are more circuits available on a bar than there are, it works fine.

[Stu]

There could very well be a patch bay on the end of the IWB cabling run which would enable them to be plugged into another source of hard power, be it a distribution box, dimmers with dedicated non dim modules in them, even a 13A-15A on the end and into a mains ring!

[david.elsbury]

OP says dimmers are hard wired..... :)

[Stu]

Whoops! :-) oh well, point applies on similar situations!

[top-cat]

Can it reasonably be expected that the rig / desk is used with the appropriate channels permanently at 100%, for its lifetime and in every scene including blackouts?

 

It depends on your desk. I have some fixtures powered from dimmers running at 100%; in the desk I have the 'dimmers' set at 100%, not assigned to any kind of control, labelled clearly as non-dim, and set as exempt from DBO; and have no issues in this regard.

 

However, this is not to say I have no issues.