Like it or Not. The outdoor CU/DB is here to stay.

In the recent years there has been a massive increase in the use of outdoor switchgear for the domestic dwelling (PV, EV, Heat Pumps etc).  They are mainly metal but this then brings in the question of RCD protection for the enclosure itself and the characteristics of the supply cable to the CU/DB.


EG Is it OK for the CU to be fed from Henly Block (Other Brands are available) with only the protection offered by ( BS 1361 ) the main cut out fuse?  The standardized BS 1361 breaking capacity of these fuse-links is 33kA at 0.3p.f. However to cater for increasing fault levels all Lawson house service cut-out fuse-links have been ASTA tested to 80kA at 0.15 p.f.

A few suggestions

Height from floor and positioning.  IE can a child touch it, if so should the metal enclosure go inside a plastic or GRP enclosure?  GRP being preferred.

A breather plug/vent

A sticker on the front Stating.....All Penetrations to Enter from Below

A sticker on the front Stating.....IP rating, IK rating for the enclosure and Pollution Degree rating for the breakers inside if it is sold as a kit.

Pollution degree (IEC 60664-1)

Pollution degree    rough environment
1    In a clean environment or enclosed equipment
2    most common environment
3    Harsh environments such as factories
4    Outdoors where it is mainly exposed to the elements

As always please be polite and respectful in this purely academic debate.




Come on everybody let’s help inspire the future.

Parents
  • 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

Reply
  • 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

Children
  • 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.