Enclosure recommendation .

[RickH]

Small project undeway.

Need a surface mount plastic box, to mount a couple of electrical modules.
Not huge …. Not much bigger than a 2 gang box or cooker switch.

Not much in the way of heat output, but some ventilation would make sense.
Would like the enclosure to be dust proof but no need for any water resistance as indoor use.

Anybody know of something suitable ?

 

[JohnW2]

Not much in the way of heat output, but some ventilation would make sense. ... Would like the enclosure to be dust proof

I suppose that depends upon what size of dust particle you want to keep out, since 'ventilated' and 'dust proof' are not particularly compatible

 

[JohnD]

A metal box, preferably with fins, will shed more heat than plastic.

 

[JohnW2]

A metal box, preferably with fins, will shed more heat than plastic.

Indeed. People tend to forget that the crucial thing is how well heat can get through the walls of an enclosure and be dissipated iunto the surroundings.

If, hypothetically, an enclosure were 'infinitely well insulated' (no heat transfer through walls at all) then, no matter how small the rate of heat production by the contents, the interior temperature would carry oin rising continuously, until the contents melted, blew up or whatever! Whilst that obviously doesn't happen in the real world electronics which generate only tiny amounts of heat can get pretty hot if they are inside an enclosure which is a substantial barrier to heat flow.

 

[RickH]

I suppose that depends upon what size of dust particle you want to keep out, since 'ventilated' and 'dust proof' are not particularly compatible

normally I'd agree .. but IP5 for example allows for limited ingress.
Something as good as consumer unit ... with from flap close dust does not get into any great degree.
Just concerned about putting a switch mode psu in a sealed box, maybe some is aware of some with vents

 

[RickH]

Indeed. People tend to forget that the crucial thing is how well heat can get through the walls of an enclosure and be dissipated iunto the surroundings.

If, hypothetically, an enclosure were 'infinitely well insulated' (no heat transfer through walls at all) then, no matter how small the rate of heat production by the contents, the interior temperature would carry oin rising continuously, until the contents melted, blew up or whatever! Whilst that obviously doesn't happen in the real world electronics which generate only tiny amounts of heat can get pretty hot if they are inside an enclosure which is a substantial barrier to heat flow.

exactly why I trying to choose the right box to use.
Pregnant plug type USB & similar PSUs are in effect in sealed boxes, they rely on the surface of the plastic itself dissipating the heat.
Alternative thought would be a small 2 way breaker box ... something like an unpopulated one of these https://www.screwfix.com/p/mk-sentry-4-module-2-way-part-populated-garage-consumer-unit/568kp

 

[Deryck Tintagel]

Something like this?

MB158055 | Hammond Polystyrene PCB Mounting Enclosure, 150 x 80 x 55mm | RS

uk.rs-online.com

Can be wall mounted with key slots on the back