How safe is a mains 12v supply?

[jonathan]

Just wondering how a typical mains powered 12v converter fares under heavy dew conditions, if it dews up inside it might blow itself and pop a mains fuse (hopefully the portable RCD first though). Shouldn't be any risk of electrical shock, but if the entire casing is dripping with dew then who knows?

I have an old blue Halfords unit that has a power selector switch and a single power socket on the front. There's a car fuse on there too. It can chuck out a fair old amount of amps at 12v, which is the scary part for me.

Should such a unit be wrapped up in a thermal blanket to delay the onset of dew?

[Charon]

Converters give off a fair amount of heat, I do not think wrapping it up will be a good idea.

[jonathan]

So they are likely to keep themselves dry then?

[Starlight 1]

It do say , Not for outside use.

[themos]

I've never seen one (a Maplin unit) get wet yet, even when parts of the laptop were dripping water.

[Keiran]

I wouldnt wrap it up, the heat could cause a fire. I dont like using mains outside, I have a big leisure battery i use. May be worth getting a big water tight box to put it in.

[robbieince]

If I have mine outside and its dewy, I put it on a tripod chair (you know the ones with a small seat and three legs, a bit like a shooting stick) and cover the top completely with a plastic carrier bag, loosely. So, no rain from above, minimised damp from below and the air can get in from the bottom and the heat from the supply keeps the dew at bay. Never had a problem and it does get pretty wet when at Galloway and Kielder.......

[Islander]

As above, just cover it loosely so that air can still circulate. You shouldn't be able to get a shock directly from the case as it should be double insulated (look for a box in a box symbol on the labels). Any current leakage that doesn't return directly via the neutral lead that's over the RCD's trip threshold will cause it to trip anyway

[jonathan]

If I have mine outside and its dewy, I put it on a tripod chair (you know the ones with a small seat and three legs, a bit like a shooting stick) and cover the top completely with a plastic carrier bag, loosely. So, no rain from above, minimised damp from below and the air can get in from the bottom and the heat from the supply keeps the dew at bay. Never had a problem and it does get pretty wet when at Galloway and Kielder.......

That sounds like a plan!

I have yet to secure a good leisure battery, when I have tried in the past they were always out of stock or didn't have the one that I wanted (or I didn't have any faith in the online retailer who did show some stock). This is my goal, to run on batteries, but until then I'd like to give the 12v mains adaptor a go, as with four dew heater tapes I am expecting to draw quite a bit of current.

[r3i]

I've got mine, a Ripmax Pro Peak 20A, inside a clear 'air tight' plastic food container. I drilled holes in the side for the mains input and 12V output cables so it's no longer air tight but is certainly dew proof. There seems to be sufficient air flow so It never gets over warm.

[Mr Spock]

I've never had any problems with mine. Damp, cold, it doesn't seem to matter

[Spikey]

I also keep mine in a plastic box with an extension block running back to an RCD socket in the house. It's not the type of box with a totally sealed lid.

On really dewy nights I've never had a problem. It gets nice and warm in the box as I've left room for the air to circulate. One thing I have done occassionally is to drape a tea towel loosely over the top of the box if dew is forming.

It catches t quite nicely and the dew can't then drip into the inside.

[themos]

I think that dew water is highly deionised so conducts electricity less well anyway.

[Tinker1947]

Why not have the PSU inside and run low power cable out side, mines 10m long there's no voltage drop.....Maplin 7 Amp 13:8 Volt

[Sobel]

Good post, I too am in this quandry.

I posted in the wrong section on here originally, but I was intending to go down the route of having an RCD in the mains, running a weatherproof extension cord out to a weatherproof box, inside which the 12v converter and scope mains adapter will sit, with the cables coming out of the box into the scope and dew heater.

I posted in my other thread tat I have read a lot of people refuse to use mains to power their scope due to the risk of power surges blowing the electrics in the scope itself. Dunno how concerned I should be, and if I should abandon mains altogether and focus on a power tank?

[kirkster501]

It will not be an issue. The constant heat rising off the electronics in the PSU will keep any dew at bay. Only if it actually rains will you have a problem or if you switch the PSU off for some reason and leave it out whilst you observe for a few hours and why would you do that?