Control/Dimming Possibly a basic question...attach 13A lamp to dimmer socket?

wpriddis

New Member
Hello - possibly a dumb question but my knowledge is a little basic!

I'm looking at maybe having a practical household lamp on stage as part of a show, but I want to be able to dim it from my lighting desk. The one we have currently has a 13A plug and a dimmable bulb. If I buy a 15A round-plug to 13A socket adaptor, can I just plug it straight into my dimmer rack? Or will that cause problems? Working on UK electrical system here.

Cheers!
 

almorton

Well-Known Member
That will work fine, as long as it's the right kind of lamp, says a UK based member.

Is it LED or tungsten? LED tend to work better with trailing edge dimmers, and most theatre dimmers are leading edge,but it will work - do you happen know the minimum load for your dimmers?

Personally, I'd just swap the BS1363 3-pin square plug for a BS546 15A round pin. You don't want to have to change the fuse in the plug if the lamp fails.
 

wpriddis

New Member
Ah perfect, cheers! Yeah it's an LED bulb - and I think the minimum load for my dimmers is 0.1A? Struggling to find that info but I think that's it?

That makes sense to swap the plug over. My plug maintenance skills are pretty shoddy at the moment so I might stick with the adaptor as a short-term solution. I don't mind changing fuses so if that's the worst that could happen it should be OK?

Thanks so much for your help! My knowledge compared to others on here is pretty basic so appreciate it!
 

RonHebbard

Well-Known Member
Premium Member
That will work fine, as long as it's the right kind of lamp, says a UK based member.

Is it LED or tungsten? LED tend to work better with trailing edge dimmers, and most theatre dimmers are leading edge, but it will work - do you happen know the minimum load for your dimmers?

Personally, I'd just swap the BS1363 3-pin square plug for a BS546 15A round pin. You don't want to have to change the fuse in the plug if the lamp fails.
@almorton Could a low wattage dummy load improve @wpriddis 's dimming, especially at the low end?
Toodleoo!
Ron Hebbard
 

almorton

Well-Known Member
Depends so much on what the minimum load is for the dimmer, the type of the dimmer, and what type of load is being dimmed. My experience with trying to dim "dimmable" LEDs on a standard Strand dimmer and expecting them to behave like incandescent is that you're wasting your time.

As I've mentioned before, we swapped a single lamp for a dimmable LED, leaving the rest of the incandescent load in place, so we had about 750W of tungsten load and it made no difference - the LED still popped on and had a very compressed range, popping on at about 25% brightness when the dimmer was at 10% and then fading to full by the time the dimmer was about 50-60% up. Hideously out of synch with the rest of the lights on the circuit, which of course dimmed nice and smoothly.

If @wpriddis was wanting to control a practical with a d0m3st1c tungsten bulb, then it would be fine, although it might need a small ballast to meet the minimum load. Our Act6 dimmers claim to need a minimum load which is only 60W, and in practice they seem happy down to 40W, so it's a case of suck it and see. But it won't do any harm. A 60W lamp might be a decent load to try.

One of my long term projects is to fabricate some 12V substitutes for mains lamps, so that they can be dimmed with a low voltage dimmer and substituted in practicals. My theatre has a reasonable stock of "old" lamps (MR16/GU10 spots, tungsten globes and candles, and enough 650W and 1000W lamps to now last us for years to come if we need them) but not everyone is in that same position, and proper, tungsten filament lamps, are like hen's teeth now in the UK.
 
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almorton

Well-Known Member
why not dump the LED in the practical and use a "normal" incandescent?
Because here in the UK they're damned near impossible to buy. We'd love to continue using "normal" incandescent lamps in practicals, but you really have to search, often on "questionable" eBay sites, for tungsten filament lamps. They started phasing them out over twenty years ago, first replacing them with compact fluorescent, then with LED. Once the LED market was established, the inefficient tungsten and tungsten halogen lamps were legislated off the market. You can't now bring new product into the sales channels except under very tight restrictions (which don't cover any standard domestic lamps), so high power theatre style lamps are still available (at an increasing price) but domestic lamps, as used in a practical, are not (officially) for sale.
 

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