How easy is it to blow the DNO's cutout?

[Mark42]

I've been volunteering at my local village hall, installing audio and light systems. Converting what was originally an underused sports hall into a venue for bands and theatrical events.

As with most of my projects, it has got out of hand and I've now reached a load schedule of 56A for my lighting rig alone, nearly all of which is LED.

Of course there's diversity: never will all fixtures be at 100% intensity together, but adding the legacy overhead of about 50A (hand driers, kitchen kit, kettles, portable heaters) I worry that I may potentially be stressing the supply. It's only a mickey-mouse domestic single phase cutout, probably containing an 80A fuse.

In others' experience, how likely is LED inrush to blow the cutout? It would be unfortunate if a widespread strobe or flash lighting cue closed everything down by killing the building's power!

Of course careful programming can keep the load down, but it may not always be me on the Avolites desk. If we have some old-skool techno operator who goes bananas, there may be a problem.

I have wired everything on a new three-phase submain DB (with L1+L2+L3 temporarily commoned), and asked the committee to upgrade to 3 x 100A, but it will take years to get agreement, if ever.

 

[OnlQQker]

Video mapping can work wonders, and all that's needed is a projector, socket and after effects. Takes a while to do the mapping, but if you map parts of the building that never alter then you can use this forever.

I used the ceiling at my daughters prom in a nightclub once, all the kids faces were projected onto the ceiling and morphed into each others with a universe background, I'd then change position and throw the projection over to different walls whilst leaving the universe playing out on the ceiling with shooting stars etc. It caused the same reaction as video below. The projectors are a lot cheaper if you approach the manufactures directly, you'll need a large venue projector, the small one's give you less coverage. If you suspend something clear from the ceiling, say a clear piece of perspex that is see through, you can start messing around with 3d mapping. Unless you've seen it live youtube video doesn't really capture it very well!

 

[DPG]

Video mapping can work wonders, and all that's needed is a projector, socket and after effects. Takes a while to do the mapping, but if you map parts of the building that never alter then you can use this forever.

I used the ceiling at my daughters prom in a nightclub once, all the kids faces were projected onto the ceiling and morphed into each others with a universe background, I'd then change position and throw the projection over to different walls whilst leaving the universe playing out on the ceiling with shooting stars etc. It caused the same reaction as video below. The projectors are a lot cheaper if you approach the manufactures directly, you'll need a large venue projector, the small one's give you less coverage. If you suspend something clear from the ceiling, say a clear piece of perspex that is see through, you can start messing around with 3d mapping. Unless you've seen it live youtube video doesn't really capture it very well!

I like that - very impressive.

 

[davesparks]

As for control, I abandoned Avo many years ago and have owned Chamsys ever since

I've heard from a few people that Avo ain't what they used to be these days, I guess they must have struggled a bit with the shift to LED and not be shifting any where near as many ART racks!

I've got an early tiger touch somewhere that still gets a bit of use, and of course the obligatory rollacue pearl with wooden sides I want to build in to a coffee table.

Not that I've operated any LX desk in years, I'm very much settled in the 'I'll build it, someone else can operate it' camp these days.

 

[Simon47]

And to think, the last lighting desk I used was a 12 channel manual Furse - and we thought it was the bee's knees having two sets of faders with a master each making crossfades easy ! Still a big step up from rheostats.
But the thyrister units didn't keep your coffee warm.

 

[Gavin John Hyde]

I blew a DNO fuse yesterday as it happens, fitting a change over switch and the little copper busbars at teh bottom were slightly out of alignment, powered up and heard faint thud/pop.. meter was blank and found fuse blown. called SSEN who were there in half hour to replace. it blew instantly.

 

[Rockingit]

And to think, the last lighting desk I used was a 12 channel manual Furse - and we thought it was the bee's knees having two sets of faders with a master each making crossfades easy ! Still a big step up from rheostats.
But the thyrister units didn't keep your coffee warm.

My first outing at lighting involved an 11yr old me who very literally knew enough to be dangerous very nearly setting the school hall on fire by over-loading the plug and play green ginger sliders and leaving them at various stages of extra-hot and buzzing for three hours........

 

[Simon47]

I do recall one time there was a group of students who'd formed a band, and they had a gig in the hall. They'd asked to use the stage lighting, and reluctantly had been given permission on the condition that there was to be no flashing of the lights - the English teachers who were in charge of Drama were terrified of blowing a bulb, we'd just bought a couple of spares at something like £20 each in early 80s money. Anyway, I got nominated as the responsible person to operate the lighting for them.
The next morning was April 1st. As I went into a physics lesson (our physics teacher was in charge of technical matters relating to the hall), I casually mentioned that we'd blown one of those expensive bulbs - and of course, he fell for it. But it backfired on me, because at break time, he went and did the same to one of the drama teachers - only he told her we'd blown two bulbs. I got a small telling off for raising her blood pressure.

Ah, the things we could get away with back then. Our control booth was at the back of the ranked seating, and the only way in and out was through the audience. But we realised that if we left a window open on an upstairs corridor, and used the fire door right next to the door into our booth, we could walk across the flat roof - typically in the dark, and with no rail at the side where it was a nice drop onto solid paving.

Back to the question, I blew a main fuse once - through a moment's inattention. I normally attach a spare MCB to the busbar with a bit of wire to the earth bar for R1+R2 tests, but following a house move I didn't have it with me when I was doing an EICR. Having done live tests (Zs, Ze), something must have distracted me, and I went to apply a L-E lead so I could go round doing R1+R2 tests ... with the power still on. I was actually surprised how little of a flash and bang it made, and how little it took out of the crock clip.
What was more irritating was the attitude of the DNO when I called them. The person at the other end flat out refused to take my number, insisting on me giving the one that matched their records - of the tenant who was at work. The engineer then proceeded to go to the wrong street (not uncommon as the postcode isn't too accurate and the address is confusing). And as the tenant had their phone off due to the nature of their work, they couldn't get hold of me.
So after no-one has turned up for a while, I rang them back, to be told he'd been, there was no-one in, and he'd gone - and perhaps they'd be able to get someone back tomorrow. At which point I used "quite persuasive" language until they agreed to call the engineer and get him to return. The tenant had now got the message they'd left, and between us we managed to work out where the engineer was, walk down, and redirect him.
For good measure, he couldn't find any seals to reseal the cutout.

 

[nicebutdim]

I do recall one time there was a group of students who'd formed a band, and they had a gig in the hall. They'd asked to use the stage lighting, and reluctantly had been given permission on the condition that there was to be no flashing of the lights - the English teachers who were in charge of Drama were terrified of blowing a bulb, we'd just bought a couple of spares at something like £20 each in early 80s money. Anyway, I got nominated as the responsible person to operate the lighting for them.
The next morning was April 1st. As I went into a physics lesson (our physics teacher was in charge of technical matters relating to the hall), I casually mentioned that we'd blown one of those expensive bulbs - and of course, he fell for it. But it backfired on me, because at break time, he went and did the same to one of the drama teachers - only he told her we'd blown two bulbs. I got a small telling off for raising her blood pressure.

Ah, the things we could get away with back then. Our control booth was at the back of the ranked seating, and the only way in and out was through the audience. But we realised that if we left a window open on an upstairs corridor, and used the fire door right next to the door into our booth, we could walk across the flat roof - typically in the dark, and with no rail at the side where it was a nice drop onto solid paving.

Back to the question, I blew a main fuse once - through a moment's inattention. I normally attach a spare MCB to the busbar with a bit of wire to the earth bar for R1+R2 tests, but following a house move I didn't have it with me when I was doing an EICR. Having done live tests (Zs, Ze), something must have distracted me, and I went to apply a L-E lead so I could go round doing R1+R2 tests ... with the power still on. I was actually surprised how little of a flash and bang it made, and how little it took out of the crock clip.
What was more irritating was the attitude of the DNO when I called them. The person at the other end flat out refused to take my number, insisting on me giving the one that matched their records - of the tenant who was at work. The engineer then proceeded to go to the wrong street (not uncommon as the postcode isn't too accurate and the address is confusing). And as the tenant had their phone off due to the nature of their work, they couldn't get hold of me.
So after no-one has turned up for a while, I rang them back, to be told he'd been, there was no-one in, and he'd gone - and perhaps they'd be able to get someone back tomorrow. At which point I used "quite persuasive" language until they agreed to call the engineer and get him to return. The tenant had now got the message they'd left, and between us we managed to work out where the engineer was, walk down, and redirect him.
For good measure, he couldn't find any seals to reseal the cutout.

I know nothing about stage lighting, but my old school had an ampitheatre for an assembly hall, which was obviously used extensively for performances of all sorts. Control booth was above one side of the stage, looking out over the 'theatre' and stage. Not much more than a crawl space with all manner of equipment and accessed by ladder, but very cool for a school nonetheless.

 

[nicebutdim]