Outdoor lighting

[sandall]

Took a walk round Kew Gardens this morning, following the Christmas lights trail. Despite the almost-daily (sometimes really heavy) rain, not one of the many hundreds of Par-cans or dozens of Source-4s, movers & other assorted luminaires had any sort of weather-protection; the lasers in front of the Palm House had plastic bags over them, but nothing else. While lights will quite happily keep themselves dry once they are hot, I'm surprised that lamp-holders full of several hours-worth of rain don't cause problems on power-up - the show has been running for a fortnight already, so it's obviously not a major issue, but it does rather go against everything one has been taught over the years about electricity & water :huh:

[timsabre]

They don't tend to get water in lampholders. Will trip an rcd if they do. Par cans pretty much don't care but do go rusty, occasionally the lamps explode.

 

Movers are not so good in the rain, are you sure they weren't something waterproof like a g-spot or something? You can get waterproof led source 4s as well.

[indyld]

Sounds like outdoor lighting circa 1990. Water running out of PAR cans, theatre kit in the bushes and Tesco-bagged 15A connectors.

 

Some gigs even the supposed covered stages can get soaked. At the end of this summer, a truckfull of soaked kit came back from Europe and the "gaffa tape covering the joins in the case" solution that the crew applied to the movers didn't stop a load of PSUs blowing up.

 

Movers are not so good in the rain, are you sure they weren't something waterproof like a g-spot or something? You can get waterproof led source 4s as well.

 

A few weeks ago, a load of Maverick Storm 1 Wash lights turned up in stock. IP65 n all (and the associated heft when lifting them).

 

Maintenance plan for the next 3 years is jet wash them after the show and send anything that doesn't work back to Chauvet. Haha.

[sandall]

They don't tend to get water in lampholders. Will trip an rcd if they do. Par cans pretty much don't care but do go rusty, occasionally the lamps explode.

Movers are not so good in the rain, are you sure they weren't something waterproof like a g-spot or something? You can get waterproof led source 4s as well.

I would have thought that with driving rain a Par lamp-holder could end up like a half-full ceramic bath-tub!! I couldn't get close enough to see what the movers were, so they may well be waterproof ones. TBF there may well be a lot of internal sealing in all the fixtures. I work on one winter gig with a load of theatre generics in trees, rain or not, & it all survives, but that's only 1 night - this stuff is sat on wet grass for a 6 weeks run (plus a few more weeks rigging).

[alistermorton]

Remember, until very recently at minack they had pars permanently rigged in rain and sea air. Like many other companies we've rigged ordinary stage kit there all week (in our case pars and sils) and they just keep working.

[Brian]

Quick question.... How conductive is rain water?

[timmeh2]

Hi

 

Very. Far higher than tap water due to dissolved CO2, salt and particulates from the atmosphere.

 

It's also mildly acidic.

 

All the best

Timneh

[sandall]

Very. Far higher than tap water due to dissolved CO2, salt and particulates from the atmosphere.

Unlike distilled water, which was (is?) used for cooling the anodes of high-power radio transmitters - tens of kV across a column of water!

[indyld]

Since this post, I've been reflecting on real experiences of old skool 'outdoor' lighting (e.g theatre lights shoved outside) vs. common practice now. Arguably, many electrical protection systems are more comprehensive than they were 20 years ago, operatives are more 'trained' (OK, let's not start that discussion here) and it's a long time since I was involved in the kind of outdoor install that involved Tesco bags and rusty PAR cans.

 

Not sure such installation methods would stand up to much scrutiny of the modern H&S consultant, proper application of BS7909 and such. Back then, as now, people generally try to do their best with the kit even if now it's more likely to involve using a rubber box, pretty CEE connectors and an IP-ish fixture - rather than standing a dimmer rack on a pallet to keep it out of the puddle, and putting the lid across the top of it to keep the rain off.

 

I'm not sure I'd go back those old techniques even though I kinda know that they were fine when used with caution and knowledge. I assume this is because I now know the risks ... of getting hauled up in front of a judge and not having a good answer. :-)

[bigclive]

While rain water is pretty clean and high resistance it only takes some dust or dirt to make it conductive. With traditional PAR cans the main issue tends to be a wet ceramic holder conducting to the assembly that allows the lamp's beam angle to be adjusted. In use the heat will rapidly dry out the ceramic.

 

Some outdoor installations are breathtaking in their lack of proper safety considerations. Even more so when a lot of the cabling is done by volunteer labour or general crew.

[adam2]

In parts of Southern Europe, bars and cafes sometimes provide outdoor illumination by standard fluorescent light fittings tied to tree branches, the rain falls into the fitting and drips out again. Eventually the fitting succumbs to rust, but they last some years.

 

I would not of course recommend doing this, but it seems to work surprisingly well in practice,

 

 

 

[alistermorton]

While rain water is pretty clean and high resistance it only takes some dust or dirt to make it conductive.

I'd hazard a guess that sea mist and rain is a touch conductive:-)

[bigclive]

While rain water is pretty clean and high resistance it only takes some dust or dirt to make it conductive.

I'd hazard a guess that sea mist and rain is a touch conductive:-)

 

In a certain Edinburgh location the main villain is the Haar. A very dense sea fog that can penetrate where mere rain cant and results in water on ALL surfaces it can reach. It trumps horizontal driving rain for the amount of issues it causes.

 

The Haar isn't salty - just very penetrating. You could literally have a bucket upside down and there would be water on all of its inside surfaces.

[alistermorton]

I've been at a tattoo when such fog descended. Being able to hear a pipe band but not see it as it disappeared into the mist at the other end of the esplanade was quite something. The lone piper was almost invisible, just a shard of light through the fog aiming at, well, almost nothing.

[Brian]

Unlike distilled water, which was (is?) used for cooling the anodes of high-power radio transmitters - tens of kV across a column of water!

 

I don't know about radio but in TV, where Klystrons were used in the output stage, the Anode was nominally at ground with the cathode some tens of kV negative wrt ground. Water cooling of the anode using distilled water (actually, technically, I think it's de-ionised water) was done but this meant the potential across the cooling system was only a few volts.

 

 

Brian

(ex-transmitter engineer)