sirrus Posted February 3, 2009 Share Posted February 3, 2009 I've hunted blue room and the internet for weeks but to no result. Right, Straight to it... How exactly do I attach a "free standing lamp" to a dimmer (i.e. either a Z88 Chilli 24 way running on three phase with 2k to play with on each channel or just a Budget MKII with about 5A per channel). I have heard about dummy theories but do not fully understand how it works. Please advise as I have a director after me who wants to have several Practicles controlled from the LX desk and currently im under the impression that by just swapping the 13a fused plug for a 15a plug, attaching it to the dimmer and pushing up a fader wont yield the "best" results. Or will be "steppy" in its dimming curve. Do I need to insert a transformer in between the dimmer socket and lamp? Please advice and many thanks in advance. Link to comment Share on other sites More sharing options...
mark_s Posted February 3, 2009 Share Posted February 3, 2009 Plug it in, and if it doesn't work plug something else into the same dimmer and hide it in the wings. Simple. :P Link to comment Share on other sites More sharing options...
jonathanhill Posted February 3, 2009 Share Posted February 3, 2009 Any tungsten lamp will dim when attached to a dimmer, but you are right in saying that the dimming curve may be 'steppy', especially with older analogue dimmers which need a 'minimum' load to actually dim with any sort of curve which looks acceptable. Try adding another load to the practical's dimmer, say a little flood handily placed in the dimmer room far away from the action, and that should smooth out the dimming curve. Transformers are for stepping up or down the input voltage. Not appropriate for a 240V lamp running off a dimmer using 240V as its supply. As noted in several other threads (sorry Mods) be wary of three phase electricity, and try to conform to 'best practice' and keep phases distinct to areas (one phase for Foh, one for stage, one for overhead) Hope this helps. Link to comment Share on other sites More sharing options...
sirrus Posted February 3, 2009 Author Share Posted February 3, 2009 Sorted. Thanks guys :P Link to comment Share on other sites More sharing options...
pritch Posted February 3, 2009 Share Posted February 3, 2009 It really depends what the lamp in question is. The dummy load is there because dimmers sometimes can't cope with dimming a low wattage lamp. You may get good results by swapping the plug and just plugging it in to a dimmed supply... or you may not. Suck it and see! If it doesn't work well, then you'll need to connect another lamp up, off-stage, in order to make it work nicely. You mentioned transformers... are you dealing with low voltage lamps here? If so, make sure the transformer is dimmable. This thread may be of use. The general consensus seems to reflect my experience, which is that you often don't need a dummy load, but just give it a go and see how you get on: http://www.blue-room.org.uk/index.php?show...mp;#entry262373 Edit: Really must learn to type an awful lot faster! There were no replies when I started writing this! Link to comment Share on other sites More sharing options...
Davethsparky Posted February 4, 2009 Share Posted February 4, 2009 If you want to know before you get on site and have a chance to try it then looking at the chilli spec sheet the min load for the models with 10 amp channels is 0.1 amps. This equates to 24 watts at 240 volts and 23 watts at 230 volts, so as long as you have a load greater than this you should be fine. For the other dimmers you can just look up the min load and work from there. A concurrent post has been automatically merged from this point on. As noted in several other threads (sorry Mods) be wary of three phase electricity, and try to conform to 'best practice' and keep phases distinct to areas (one phase for Foh, one for stage, one for overhead) If he's got chillis then he'll be stuck with outlets wherever they were put by the installers and so will have little or no control over the 'phasing out' of the rig Link to comment Share on other sites More sharing options...
theatrcymraeglampy Posted February 4, 2009 Share Posted February 4, 2009 As noted in several other threads (sorry Mods) be wary of three phase electricity, and try to conform to 'best practice' and keep phases distinct to areas (one phase for Foh, one for stage, one for overhead) The requirement to separate phases was removed along time ago in installations that have sufficient insulation in cable in a multicore; as has been covered many times. Link to comment Share on other sites More sharing options...
AndyJones Posted February 4, 2009 Share Posted February 4, 2009 The requirement to separate phases was removed along time ago in installations that have sufficient insulation in cable in a multicore; as has been covered many times. Just because the regs say that you can keep phases together on the same bar doesn't mean it's something that should be done. Where ever reasonably practical it is worth keeping phases separate. Because at the end of the day: Just because the regs have changed, it doesn't mean that you won't get 415 volts across you when some thing goes horribly wrong! Where ever you take your dimmer channels from, I would make sure you take all the practicals from one outlet box. That way you can be fairly sure the phasing will match. HTH AndyJones Link to comment Share on other sites More sharing options...
david.elsbury Posted February 4, 2009 Share Posted February 4, 2009 I was hoping not to get involved in this topic. But it probably is worth repeating this quote from James That requirement is no longer in the current regs. If you consider all the faults required to get to this point, 1 ) Safety Earth failure in kit A2 ) Safety Earth failure in kit B3 ) Live > Chassis in kit A4 ) Live > Chassis in kit B it is highly unlikely (Of course if you are talking stage lights on the same bar you can add) 5 ) Safety earth failure on the bar Bar 6 ) Chassis > Bar failure on one lantern!!! James It is extremely unlikely that all these faults will happen. That is the only case where you will see 415v, otherwise you will see 240v... which you would see anyway, 3 phases or 1 phase... OP, please read this topic here as we have covered this (split phases) question/argument before, and if there is a need to continue the discussion, it could be done in that thread... Link to comment Share on other sites More sharing options...
Paul Joines Posted February 4, 2009 Share Posted February 4, 2009 I've hunted blue room and the internet for weeks but to no result. Right, Straight to it... How exactly do I attach a "free standing lamp" to a dimmer (i.e. either a Z88 Chilli 24 way running on three phase with 2k to play with on each channel or just a Budget MKII with about 5A per channel). I have heard about dummy theories but do not fully understand how it works. Please advise as I have a director after me who wants to have several Practicles controlled from the LX desk and currently im under the impression that by just swapping the 13a fused plug for a 15a plug, attaching it to the dimmer and pushing up a fader wont yield the "best" results. Or will be "steppy" in its dimming curve. Do I need to insert a transformer in between the dimmer socket and lamp? Please advice and many thanks in advance. If you're using low wattage bulbs below 100W then yes you may get flicker and curve problems. The old fashioned answer is to change the plug (requires PAT test) pair up the channel with another lantern offstage (a spare 500W is perfect) to take the load from the dimmer. smooths it all out. On an H+S tip, rig it on a stand or bar, dont put it face down on floor, barn doors closed is OK if not on for too long. If this is impractical use 100W bulbs and dont raise to 100% - usually OK Link to comment Share on other sites More sharing options...
david.elsbury Posted February 4, 2009 Share Posted February 4, 2009 The other thing about using a practical, is (say we're talking about a table lamp) you can pair the practical with a lamp rigged directly above the practical, pointing straight down. This is useful 1) as a dummy load and 2) because it makes it seem that the practical is actually "emitting more light" and looks more realistic. Link to comment Share on other sites More sharing options...
Davethsparky Posted February 4, 2009 Share Posted February 4, 2009 The old fashioned answer is to change the plug (requires PAT test) pair up the channel with another lantern offstage (a spare 500W is perfect) to take the load from the dimmer. smooths it all out. On an H+S tip, rig it on a stand or bar, dont put it face down on floor, barn doors closed is OK if not on for too long. Why change the plug? you'll only have to change it back again after the production. And it'll more than likely require a PAT test anyway. Why not just take the barndoors out if the dummy lantern has them fitted? Link to comment Share on other sites More sharing options...
adam2 Posted February 5, 2009 Share Posted February 5, 2009 The old fashioned answer is to change the plug (requires PAT test) pair up the channel with another lantern offstage (a spare 500W is perfect) to take the load from the dimmer. smooths it all out. On an H+S tip, rig it on a stand or bar, dont put it face down on floor, barn doors closed is OK if not on for too long. Why change the plug? you'll only have to change it back again after the production. And it'll more than likely require a PAT test anyway. Why not just take the barndoors out if the dummy lantern has them fitted? There would be no need to change the plug on the theatre lantern, it should already be fitted with a plug suited to the venue, probably 15 amp.The practical though is generally a d0m3estic type portable table lamp or similar, this will require the 13 amp plug to be replaced with one suited to the dimmed supply, typicly 15 amp. After changing the plug, the item should be PAT tested, though I suspect that most places wont bother. If practicals are to be a regular feature, it worth keeping a few 15 amp to 13 amp adaptors to save changing plugs. As others suggest some theatre dimmers wont correctly dim low powered lamps, most are fine though with 100 watt, and even 60 watt lamps. Link to comment Share on other sites More sharing options...
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