Outdoor switchgear what is happening?

This is a topic I didn’t ever think I would be writing an article about, however the growing trend to install outdoor metallic switchgear seems to be a growing phenomenon and I am not sure why. Well, that’s not entirely true I think I understand the reason they are used but I can’t understand why designers are opting for it based on selection and erection.

I am going to set out my specific concerns as from conversations with some in the industry of things I don’t think this has been properly considered. With a view sometimes returned that its IP rated, what about air conditioning, caravans, marinas etc etc.

1.????? Pollution degree ratings, this is not a new thing its existed in electrical design for decades. We have key guides on when and where switchgear should be used. Any outdoor switchgear, metal, plastic or otherwise should include protective devices that satisfy those requirements or be housed in enclosures that change the pollution degree environment. Directly on a wall outdoors would fall into category 4 with a possible argument for 3. Again, reference is often made to the performance of the OCPD in those environmental conditions, but we are also looking at lifespan and reliability over a service lifetime. If we are installing in areas equipment is not intended to operate within how can we have confidence those devices will operate at all times they are required to do so….

2.????? Distribution circuits against final circuits. Very often outdoor switchgear is utilised for EV, heat pumps and such with the supply to them taken directly from 100A connector blocks at the main intake. With the OCPD being the suppliers 100A fuse. Again, we have seen a shift towards metallic consumer units which are then installed in outdoor environments. No RCD protection for additional protection, 5s disconnection times and in locations they can quite reasonably be expected to interact with passing bins, children on bikes, wildlife etc etc. With the likes of EV, air conditioning and other such equipment they would usually have the electrical connections enclosed in a more robust location to any of those passing persons, be protected by MCBs at the very least and most often RCBOs. I cannot understand the comparison in those applications at any level.

3.????? PEN faults and this is more specific to EV than anything else. We know PEN faults are incredibly rare however the regulations considered them enough of risk to mitigate against them with electric vehicles. However, if metallic switchgear is installed in outdoor locations and a car EVSE enters a fault state say for a detected PEN fault the first place a consumer would go to “reset” the charge point would be that outdoor metallic switchgear. Potentially at the time it is most dangerous to do so. The risk of a PEN fault with a metallic outdoor consumer unit is no greater than a light, air conditioning or anything else. But it’s the way consumers behave when equipment enters fault states that makes this more of a risk for me. Opening the consumer unit lid while in contact with the mass of earth to turn the EVSE off/on.

4.????? The comparison to Marinas, Caravan sites. Those environments have specific considerations in the wiring regulations that set out what earthing systems can be used, how they should be installed and utilised. So far as I am aware that doesn’t involve connecting metallic switchgear directly to PME supplies on 100A service fuses. But I am happy to be corrected on that. The OCPD devices used in those areas should still satisfy pollution degree requirements and it should be remembered the final circuit OCPD would be within the caravans and boats. A totally different setup and application in my opinion.

5. Comparison to EVSE charge points with switchgear inside. Again this equipment will be manufactured to a product standard and will generally contain heat sinks to cover off colder temps and ventilation for warmer ones. For more reasons than just the switchgear. If that is suitable to be relied upon would be up to the designer/installer. I think its not a great approach in terms of ongoing maintenance and access etc. But again a totally different application. They would also be on a final circuit rather than the 100A service fuse and from the models I am aware usually include 60947-2 rather that 60898 devices.

I have made efforts to install switchgear in outdoor areas in ways I think help achieve an element of safety based on the above. It isn’t perfect and tbh I would rarely utilise that approach but in very rare cases its hard to avoid. That involves GRP enclosures, heating/cooling and PEN detection upstream of the consumer unit or local earth electrodes.

The drive to install quickly and easily can sometimes lead us towards turning a blind eye on safety. I would caution against that, and I still find it hard to think of any circumstance when I could not find a way to house domestic switchgear in a suitable place indoors. It’s part of the skill set of being an electrician and one we should not abandon because energy retailers in particular are stretching what is suitable electrical design.

I will close this article by saying IP65 consumer units have existed for a very long time. This isn’t in most cases a manufacturer issue. Aside from one or two cases when these have been marketed as outdoor EV consumer units. It is generally a selection and erection issue and so long as you are happy to use the deviation box or sign your name that its compliant with BS 7671 I guess that’s up to you.

Mark Allison 13/08/2024