ELECTRICAL FIRE! Destroys garage and we find out why. Plus some bonus electrical fault finding

Run through an investigation into an electrical fire, the cause and how we made it safe.

Plus a fault finding job on a tripping RCD.

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[MS-Patriot]

Health and Safety stood on its head. A Competent electrician with properly maintained compliant test equipment poses far less human risk than the consequences of doing a soft touch paperwork exercise that fails to identify a hazardous installation and appliance. Completely agree with your approach, good video lesson, great dog!

[jcf]

Great video, hope its reach is far and wide, people need to see what can happen. Real life! This is why I charge what I do for an eicr, and spend the hours onsite that I do. So that I can sleep well at night knowing Ive done a full, proper inspection and test

[adcuz]

Thanks for sharing knowledge. Good doggo too.

[drpantastic]

Just my 2 pence I may number wrong but when you described the connection as not being a spur coming direct from a ring I feel it is exactly that a "branch off a ring" not correctly done but though

[garrygriffithselectricalse]

Good points raised again, personally I try and do live tests, if safe to do so 👍

[Badgerooni]

This is very interesting, I always do my zs readings. At the end of the day these readings will fundamentally give you the answer yes my circuit has a low impedance path back to the transformer. Calculations are not definitive.

[pault]

Never undertood the calculated Zs method, we always do live testing (ZS) over R1/R2 + ZE, i also believe its NOT a requirement on an EICR to do R1/R2 anyway, only on intial verification

[havoctrousers]

Really interesting video. I tend to use the calculation method for non-socket circuits, but I hadn't thought of faulty OCPDs adding impedance that dead tests won't catch..

[MMG_MoonManGuitar]

Great insight mate. Very knowledgable!

[ebeddy]

Good video that’s got me thinking if I’d have picked up that on an EICR. I normally live test sockets after an eicr but might start doing lights too. However it can be a pain on things like showers and FCUs. I’d have highly likely paid it close attention as it no RCDs anyway. Good content

[effervescence]

Fridge freezer compressors and tumble dryers are the two most common appliances for causes of fires from memory. I have to admit though I rarely, maybe 1% of jobs do calculated ZS, I live test almost every job and every circuit because if you're not testing under working conditions my view has always been what's the point? To me it's the equivalent of testing emissions on a car with the engine not running and just calculating it from volume of fuel to air, not practical at all.

[zjzozn]

A few years ago I installed a new CU and wired an extension. A few months after 5 fire engines attended to put out house fire caused by fridge. Insurance covered everything except a new fridge. Luckily no life lost. Installed more smoke alarms after! Makes you a very careful worker 👍🥸

[paultipton]

I have been to a few tumble driers recently where the moulded plug has melted causing damage to the socket as well i do wonder if appliances like some Tumble driers and portable heaters have a way bigger load than the plugs can handle over a prolonged use.

[esfae]

Hello Mark, Great Content. Saved the best bit till last. Sad Dog just wants walkies 😀. What is your understanding of a high Zs not causing the MCB, Fuse etc not to operate under fault condition. I have never managed to get my head around this.

[Kxx]

Hi Mark As for the garage fire, I think we can safely say if it wasn’t the fridge freezer it would eventually have been something else . Good job it wasn’t an attached garage. From my perspective if I had found how it had been feed on a test, I would have made it a cat 1 defect and also sent the client a type separate letter explaining our concerns . Just Issuing certificates that most people can’t understand can leave major problems unattended. So we as a company did this as matter of course, also if any litigation should be presented proof of making representation can be confirmed . Sorry to sound OTT but if that fire had resulted in loss of life or injury, and the installation had been the course. Whoever’s name was on the certificate would be asked to account for their actions . I can’t remember having been out the trade for so long now whether a cat 1 should be disconnected and made safe, so I’ll pass on that one . Best wishes and kind regards 😀👍👍👍

[alanwalton]

Most testers come with a 3 pin plug test lead. So there is no reason why live testing cant be done on all socket outlets, safely.

[markrainford]

Nothing wrong with putting a fridge or freezer in an unheated space. I used to sell them to Eskimos.

[johnburns]

Maybe I never got it. A 2.5mm cable was spurred off a socket on a 32A final ring circuit, then taken to the garage (assumed by the original builders as the house is relatively new). In the garage there was a garage CU with four circuits. The spur should be fused to 13A. Looks like it was not. The 32A mcb in the main house CU failed? Why didn't the subcircuit's mcb in the garage trip out?

[paultipton]

I just wouldn't feel confident using just the calculation method, I'd rather verify with live testing.
The only circuits I would just use calculation is off peak storage heaters.

[johnburns]

I looked at this again after a year. Mark was constantly going on in a confusing diversionary way about z's and its testing and regs, instead of explaining the circuit setup and what really happened - then go into z testing, etc. A fridge can catch fire, with the electrical side still drawing the required current so nothing will trip or a fuse blow. Mark did not say if the house mcb was turned off manually by someone or tripped, because of the fire in the garage (cable can melt causing conductors to touch).

As I see it, the fire erupted but the OCPD's did not activate because the current draw from the fridge was not high enough for tripping - until cables melted in the garage - even though the mcb was worn.

As a side note, using the terminals of sockets as junction boxes is a no, no. My final rings have Wagos in the backboxes that take the ring's load, with the socket a spur off the Wago using 4 inches of 2.5mm flex. The only time current runs through the sockets terminals is when an appliance draws current via it. The screwless Wagos take the ring's current load, not the terminal on the sockets. The biggest cause of domestic electrical fires is loose connections. This also applies to radials of course.

Another note: A/C compressors have thermal cut-outs if the compressor gets too hot. Is this mandatory on domestic fridges? If not, I am sure cheap fridges will not have them. Then again a fire can be because of other reasons in the fridge not activating a thermal cutout or an OCPD.