Electrical Safety First - How to reduce your risk using appliances at night

Since March 2024 I've been using devices at night to take advantage of time of use tariffs low rates in the early hours of the morning but you need to assess the risk that each device presents in order to stay safe.

I have an EV but because they are very well designed with stringent safety standards and they are outside they present a very low risk when charging. Yes, we've all seen the YouTube video where a charging car catches fire but that is very rare.

I've recently installed a single ‘monoblock’ A2AHP in the hallway. With the compressor indoors that represents a risk but we chose to run it only during the daytime when we were at home for several months before having it run for part of the night or when we were away from the house. The multi-part units with the compressor outside would be a lower risk.

We don't have a tumble dryer and if we had one  I wouldn't be happy to run that at night. There are certainly ncidents of them catching fire but that may be limited to certain products or not cleaning the fluff filter frequently enough. I'm sure there are other sources of information related to how safe these are.

E-biles and E-scooters. The batteries on these are of considerable capacity and one of those going wrong has proved to be enough to destroy a house. I wouldn't charge either of those in the house if I haf one. It's possible that the bike/scooter battery/charger combination is the issue but, for me, they would have to be outside the house when charging.

I'm sure there are lots of comments out there and I thought I would try a kickstart a conversation as we move into an era where we have to trust equipment to be safe at night if we are to take advantage of lower rates at night for devices other than just storage heaters.

Peter

Good topic: thanks for airing it.

Is the heat-pump compressor more likely to burst into flames than the one in a fridge or freezer? I’m sure you’re not the type to let fluff build up around air intakes, or fail to do any of the other routine maintenance that any equipment needs if it’s to stay safe and efficient.

Basically, you have hit the nail on the head

Air to air condioners/heat pumps (it's the same thing - it just depends which end you are next to) date back to the first refrigeration units so they have a long history of development and improvements to safety so their fire risk is very low. My A2AHP uses the same refrigerant as my fridge, R290, which is butane. But butane along with most other flammable materials require oxygen to be present for it to ignite. There are thermal cut outs on the motors of both so they should disable themselves long before any overheating/leaks/fire can occur.

You also made the point of maintenance. If you keep the fluff filters clear on tumble driers then there shouldn't be any fires. If I don't clean the intake filters for the A2AHP then it will shut itself down due to to a lack of air flow. There is half a page of fault codes for the HP so I would imagine it would just shut down if it sensed anything was wrong.

There is a lot of sensible advice in the introduction but people being people will most likely ignore it which is why I've tried to give it another airing here. I dare say a section of the press will run a headline at some point to say that ‘Time of Use tariffs are Dangerous’ based on the principle of don’t let the facts spoil a good headline. There will be an increase in fatal fires for household equipment that is now running unattended but also with the occupants asleep in the house at the same time. Perhaps ToU tariffs should come with a warning or a note to say that elementary precautions should be taken before running equipment at night but that shouldn't be necessay. There are already enough warnings on the equipment but who spends the time to read all of those.

Peter

Thanks. I did a bit of research into common causes of fires in the UK. There’s quite a bit of information out there, some of it from the Home Office. In none of the lists I found did I spot heat pump (or air conditioner) faults as the cause. Heating equipment, yes - but then that covers everything from grandma’s one-bar fire falling over to boiler gas leaks. As you say, a modern heat pump from a reputable manufacturer will have no end of sensors and cut-outs to reduce the risk to negligible levels. I’d not be worried about running it overnight, but then I also take care not to be run over by a bus when I cross the road.

I didn't think to look online for causes but found this on the first hit and is quite illuminating.

https://www.morganclark.co.uk/about-us/blog/uk-house-fire-statistics/

I think appliances are quite safe and getting safer possibly because of more sensors.

And if you are interested in going down the ASHP/ fire rabbit hole …

https://forum.buildhub.org.uk/topic/2910-are-heat-pumps-a-possible-fire-hazard/

As the industry increasingly incentivises shifting energy use to overnight, it's important to highlight the necessary considerations for this shift.

Thanks for sharing your thoughts and research ​@Firedog & ​@Peter E.