I would like to think that indoors there would be no water or moisture in the the CD/DB.  Outside it is highly probable that there will be water or moisture present in the CU,  this could possibly cause damage to the Circuit Protective Devices causing them not to function properly or deliver electricution or shock when touched.

On the other hand we've been putting MCBs, RCBOs etc in outdoor boxes for decades in things like caravan hookup (and similar for boats) ... and no great disasters seem to have happened.

   - Andy.

I would like to think that indoors there would be no water or moisture in the the CD/DB.  Outside it is highly probable that there will be water or moisture present in the CU,  this could possibly cause damage to the Circuit Protective Devices causing them not to function properly or deliver electricution or shock when touched.

On the other hand we've been putting MCBs, RCBOs etc in outdoor boxes for decades in things like caravan hookup (and similar for boats) ... and no great disasters seem to have happened.

   - Andy.

On the other hand we've been putting MCBs, RCBOs etc in outdoor boxes for decades in things like caravan hookup (and similar for boats) ...
Although, until quite recently, mostly plastic boxes. But I agree, no issues when not in direct direct line of pouring water or salt spray.

Mike

Rightly or wrongly I have installed quite a few external enclosures for EV chargers. I accept that there is a potential risk of moisture causing problems if they are opened in the rain. But from my experience at least they don't seam to suffer from moisture build up on a day to day basis, certainly over the last two years at least for the ones I have installed. And I have opened older units without evidence of issues.

I have a theory of why.
All the photos of units with problems shown so far don't have doors that can be opened to expose the front of the protective devices. I believe that the seals for these doors are under less pressure than the main seals and cable gland,  therefore end up being the path for entry and exit of air. These seals are quite well protected from moisture by the doors, therefore there is little moisture to be drawn in.

In addition to this most charge points are used at least once a week for a number of hours, with presumably the protective devices dissipating 10 to 15w of heat, would this be enough to get rid of any moisture that did get in from damp air.

I wonder how the risks from damp in an external CU compare to the risks involved in drilling through walls to get an 18mm cable in to the back of a consumer unit, along with all the cable disturbance. I can't believe that many if any EV installers would be testing every other circuit they may have disturbed.

There is an option of a second DB inside. OK in a garage or under the stairs but far from popular if the CU is in the hall of a nice relatively new house or similar.