Insulation resistance and RCDs 

Best electrician channel, no doubt.

Great Vid. Top tip for nuisance trips on kitchen rings with good or high IR, fridge freezers with faulty defrost elements can be a bugger as defrost cycles only happen every number of hours, so nuisance trips are number of hours apart in time, and you cannot detect the low IR at the plug as the element is separated by the pcb relays, so you can mistake the appliance as being ok when PA tested. Can be a bastard if you didn't know this lol.

One of the few consumers of special brew that has a job, the olive gave it away.

Great Video again. As an apprentice I find these videos a helpful clarification of the theory we learn within a real world situation. Nice one!

How have i never seen this channel before . A gold mine of info

Excellent video - very clear example of procedural fault finding and highlighting the importance of recording EVERYTHING for clarity and for purposes of elimination. Good explanation of WHY it is done this way as well. You might act the buffoon but you are in fact a very clever chap.

Very sophisticated Dave drinking special brew from a cocktail glass! Interesting video, great to see a real life application of those resistance calculations they show you at college. Thanks for sharing your wealth of knowledge with others.

I only have a passing interest in domestic electrics (I'm a highway engineer) but having watched most of your back catalogue I've learned tonnes, as well as finding your overall style and production quite entertaining. Thank you very much indeed.

Just a great video, most electricians just don't get this kind of theory.

Very well done. Great use of applied mathematics to narrow down the search. I hate dealing with RCD tripping on crappy split load boards, always happy when the unplugging of all the appliances remedies the fault.

Dave , I am an electrician and have been for some time. I just want to say that you have opened my eyes as to due care and attention . I mean to say that there is always more someone can do so thank you!

Good tip that you must disconnect the Neutral to isolate and potential earth faults on the other neutrals. Thanks for great video

Thank you David for an excellent video. You are like my tutor back in the day was doing my City and Guild course!

An absolutely brilliant diagnosis sir.well done.

Really interesting to see you working through the problem !!

Knowledge is power , a great example of how logic and learning ultimately provide great job satisfaction. No better feeling.

One of your best. Real world problem solving, I actually enjoy the challenge of these type of call outs. Client is never impressed but we know better :)

As an apprentice these vidoes are digital gold, keep em coming mate

I love your channel dave. I'm more a practical guy and not the best with formulae and your videos help me with dark areas in my fried brain. You have an excellent way of educating your skills, special brew which in itself deserves respect 🤝

Great video David. A really practical example of basic physics. I had exactly this problem in one my rental properties: tenant turns kettle on, RCD trips, cause was another circuit on the RCD, the kettle just provided the last few mA to trip the RCD.

Great video, thanks. Makes me pleased that I specified individual rcbo's on each circuit when we replaced our consumer unit. I've never seen anyone drinking Special Brew from a martini glass before. I have to say that this brings a very welcome touch of class to the video. 😉

My favourite cocktail, special brew-tini. Great video mate.

Great content as always buddy, as a spark not on the tools daily, these videos help to keep my mind in the game.

Great video and explanation Dave. I always find nuisance tripping to be water ingress or faulty appliances. The amount of electronics in electrical appliances these days with capacitors and filters across the supply is increasing, this adds to earth leakage currents and has a cumulative effect. The best option as you say is RCBO on each circuit but hey.. Convince the unconvincable lol. Special brew is the only answer 😋

Brilliant video, great explanation on what you're doing as well. 👍

Informative and funny in equal measure...bravo!

Special Brew out of a martini glass... Very sophisticated 😂😂😂

Your videos are gold

Excellent video, very well presented - informative and humorous

Easily the best electrical discussions on the internet are by Dave, he even makes them funny !!! Yes u r funny Dave 😜 Keep up the interesting posts and thanks 👍

Great Video Dave, keep them coming 👍

Another excellent and informative video.

Great vid. Totally agree about customers view of what's causing a trip. Totally agree about customers and consumer units. The way I put it is, no one has their friends round to show them their new consumer unit. But I long since abandoned split boards. RCBOs only for yours truly. Love the maths (Not -I'm a history graduate ffs!), but in my simple mind I've have gone straight to the kitchen socket circuit, without all the science.

Your presentation style gets better and better. I spunked my coins on RCBOs for my CU and I always buy the most expensive tyres. There are some things in life you should never compromise on - certainly anything that involves safety and you use every day. Like your CU, tyres, toilet roll and beer.

This video remind me on my most horrible RCD foult. We installed a addional outside socket. In the main board there were 2 RCD 100mA for the heat pump and a 300mA for the rest of the house. So I told the customer we have to change the RCCB with a 30mA typ. This was no problem. RCD was quickly changed, tasts were carried out and the job was finished. Untill the customers called and told me the RCCB tripped over night. So I went there and don't find any problems. After 5 times visiting the customer and 14 hours. I found the failure. There war an old time controlled heating circuit in witch N come from the lighting circuit and the L of one relay was connected to the heat pump RCD. When the timer was off there was no fault.

Great video and a very constructive maths lesson!

Nicely done Mr Savery!

Hi Dave, thanks for great videos. The draft on brew is not so special, guess that is why it trips rarely. Cheers

Brilliant vid that. Keep em coming kind sir!

Ha, ha... my fave video yet. Great information. Love your dry sense of humour. We'd have a hoot, me and you. I'm just as satirical/ ironic/ sarcastic... though not quite so 'mucky mouthed'.

Great video getting the brain ticking on a Sunday evening. Liked the cocktail too🍺🍺🍺🍺🍺

Great video, will be watching a couple more times to sink in 👌

Well a tad embarrassed..I subscribe to your channel and yet have hardly looked at your talent! The above video is going to help me no end,( got a cheeky rcd fault to get me noggin around) and to that end I shall endeavour to watch all your videos coz there just groovy..Thank you lots and lots and lots.

I usually find RCD trips are faulty kettles washing machines etc. If I'm doing a board change on an older property as a minimum it's good practice to fit a high integrity board so you have that RCBO option. Not all customers have the money to chuck at all RCBO boards.

Hi David I really enjoy your technical knowledge I thought I was clever until I saw you Really happy to see another good spark out there but seems to be a dying breed I could watch your videos all day and nice to see someone call a spade a spade

Brilliant video David, both funny and informative. I do think ring final circuits should be on their own RCBO's as there's a greater chance of an earth leakage fault occurring due to the shear numbers of electrical equipment that can be plugged in and faults introduced onto a circuit.

I got called out one rainy easter sunday by a local farm manager. Reason tripping RCDs. So disconnected circuits at the swb. Found a rat chewed cable where the septic tank circuit exited the building inside a marley end box. Fixed that one circuit down. Found next one was a Rat chewed cable directly above the switchboard in the roof space where the rats had chewed a good 300mm of the outer sheath and the primary neutral insulation away. A quick look around in the roof resulted in many other similar rat dinners. Fixed all that I could find and advised client they had a rat problem and was most likely due to the half meter deep mound of recycling waste they had piled up in the garage. Farm manager said they normally save it up then take it into town. Farm manager started clearing waste into his trailer exposing large holes in the plasterboard wall behind the wates mound. Inside the wall were two 25mm single core conduit wire tails on the incoming mains conductor, they should have been installed in conduit but this was obviously too hard for the original installer. These tails went up the wall into the exterior tariff meter box. There was no insulation on sections of both of these tails leaving 100mm sections totally exposed on the neutral and some smaller chunks out of the active conductor insulation. Another rat supper. Had to get the line mechanic out to pull the pole fuse to allow me to repair the insulation on the tails and install it in conduit up the inside of the wall. Almost 8 hours spent on call out rate due to some one not wanting to process their recycling regularly. Sent one of the residential sparks back the next week to disconnect all switches and sockets etc. in order to pull cables up the walls into the roof space to check if any repairs were needed due to rats getting into the walls elsewhere. I should add that this was a wood framed house with exterior brick, so all walls had cavities.

I will watch this video over again a few times

Nice video D. The problem with dead testing (IR) where appliances are connected is that the appliance may only present the fault during its working cycle. I see PAT testing as superficial, though it does make sure that Class I equipment is earthed, correctly fused and no visible damage to electrical cords etc. it gives no guarantee of appliance being OK whilst going through it's various segments of operation.

Excellent video Dave

Maximum respect for the use of IT and I love the dses sign . What is that, your office ? Or a workshop of some sort ? Never noticed that Appendix 5 does it really say special brew?!?! I'm inspired to look now. I always have low NE IR for old fluro circuits. Which is in fact all of them as most new ones are LED now. I wish I knew what this was about and why nobody else seems to mention the problem. I know about LN with the capacitor and electronics, but consistently in various sites over the years I get low NE too. I'm almost at the point of well in fact I am, total surprise if this doesn't happen now. As you say, it is a right pain to diagnose without disconnecting all the lights. Got it with SONs last week too, disconnected them all and it was all 9's again. Neutral to Earth. On another point, when I saw your goodie bags from ELEX after depositing that last Xcite flood and getting my bacon buttie at CEF on Friday, picked up one of them codebreaker books you had just what I've been looking for all these years but then after reading it found it still leaves a lot to the imagination. Particularly with the issue of commercial installs without additional protection, still in a quandary of what the official position is. Guess I'll go with billions of risk assessments or just disconnecting those ccts I deem dangerous without it - for instance in a shower unit with a broken cover which comes off if you touch it exposing the terminals for cleaning! No additional protection either. Mmmm.

Great video, will be watching again , I want to get back into domestic it can be challenging

Quality Vid. Great tips.

Used to look after the cooling equipment on a dairy farm where they had a bypass switch for the RCD as it wouldn't stay on in wet weather.

When doing IR tests it is purely resistive (DC), but as is happening more now is the fitting of EMI/RF filters in modern equipment, so parallel reactive (capacitive) loads, so now I'm thinking maybe we need High range ESR test gear as well. Years ago when doing hospital maintenance and installs, we often had to install 100mA and 300mA RCD's (which sounds high) cos with the capacitive leakage (from the built-in EMI filters) on permanently connected medical equipment) it only needed between 10mA-20mA to earth to trip them!

ok i have a daft question if i wanted to make a mobile protected power board much like the main house power box what devices would give me the most all-round protection given that im renting and would like to protect myself from any eventuality.

At an existing installation I would have preceded to do 250V first to make sure you don't blow up the kids Xbox on Christmas.

I had an issue of tripping with solar pv. it would occur daily around 1pm (around peak solar).

ahhh yes sounds like it was one of them jobs, even harder to find on a split load board on the RCD side !, I can imagine the frustration when you rocked up on site lol.

Another super vlog 👍 And looking very posh with best shirt on, hair brushed and posh drink 😂👍

Hi David love your videos, nice to see some talking sense and talking the job sireasly with a bit of fun and light humour, I would like to know what is the point of doing RCD tests at half times, one times and five times when we are only required to record the highest value? This seems to be a waste of time and effort, just my own opinion. You have even said your self that some of the regs are stupid and controdict the self, point in question the removal of the supply cutout should we or shouldn't we? And the video you did were you did a EICR and found no problems yet the guy who did the EICR before you condemned the installation? Great videos and work from you please keep them coming

Good work

Hi David say a single circuit on a rcbo how low would the insulation resistance reading have to be to trip the rcbo

Love this guys sense of humour but not his taste in beer :)

Great vid Dave,you sponk on as much as you like

Good video, thanks. Is there not a risk of damage to equipment when meggering, especially at above 250v? But if you DO disconnect the appliances, how do you then identify the faulty unit? Be interested to hear your thoughts. Cheers.

Good job you didn't have your special brew shaken could've been messy great vid dude.

Thanks Dave

Brilliant

You are the man.

When you done the IR test on the washing machine(I think)at the plug,it was showing 500v setting,surely you would do this on 250v first,or am I wrong ??

Drinking special brew from a champagne glass with an olive....PRICELESS........Great vid also........thanks

David... how the f##k can you drink special brew. What's your thoughts about the 2 lengths of 6mm sq that were put up the cavity in case an electric 8/ 10 is shower was needed at a later date ? I have been told that even though these 2 cables are in 1 mcb there should 1 cable approx 10mm sq . Love to hear your thoughts. Regards Don.

Can I ask how much it costs to do IR testing?

I feel their pain, our dishwasher was cause of constant RCD trips just this past Xmas, the heating element developed a tiny pin hole. Often wondered though, the RCD's are about 2 slots in size, why are the RCBO's the same width, with only little additional height as a breaker, when they do the job of RCD and breaker, what about failures of such devices...

You had me checking blue book 😂

I had the same issue. Completely random Rcd tripping. Once a week. Maybe once a month. I changed my diss board to a 12way rcbos and since no issues. I have a 20ma leakage to earth but just can’t track it down. I guess the best thing to do is to clamp each earth to see where the fault is coming from.

We had an ring main RCD at work that had been nuisance tripping for years, sometimes ever 5 mins, had been looked at by our official sparky many times but never presented the fault :( I did the usual procedure of unplugging everything ( no trip ) then plugging in one item at a time to see if one was the culprit. Anything plugged in would cause the fault :( Eventually while I was asking our sparky to look at it again he looked at it and it tripped, prior tests were insulation and does it trip at 30ma, this time he ramped up the current from zero to find that it would trip at 12ma !

Very well explained. Was it your least favourite child filming again? Keep up the good work, very entertaining again....

Phew ! Think I need a special Brew after that. Can’t stand Maths myself, but very well put over. The Solar Pv circuit should never be installed on a shared RCD By the way. In the event of Joe Bloggs getting electrocuted and the RCD doing its job and tripping, the inverter can take up to 5 seconds to disconnect, therefor injecting electricity onto the shared bus bar and Mr Bloggs.

great video as always and i have nothing to say for once lol

Do have you heard back from the customer on how things are going?

The Joy to come home on a Monday after seeing some terrible wiring and a extraction duct full of water in a bathroom to Have Dave drink out a martini glass🍸excellent in my best Montgomery voice😁

Hi David, just been watching another sparky with client who was having an RCD tripping issue, I'm not a qualified Sparky but been an electronics engineer (now retired) for most of my life, he was going all over the place and ended up not really solving things but the fault just stopped so left telling the client that it was more than likely her washing machine? I never once heard him mention a possible rogue RCD what's your take on things, as a non Electrician if that happened in my home my first call would be the RCD, I do still have the necessary test equip. so would have 'hammered' the RCD first with under,ramp and over tests just to see how it behaved?

Hi,just wondering do you not have to make sure everything is unplugged before you do the test ?cheers

ok that’s just weird the special brew in a martini glass is weird but throwing a olive in there as well wtf 😂😂😂 Your a mad head. but that aside excellent explanation excellent video man

Did you run out of babysham ?

Have you tried Skol Super, a lot less bitter the SB. That said, Polish strong lagers are in a different league entirely.

..and this is why a good electrician should be paid more...!

The Keith Floyd of sparky world 😎🍻🍻

There's a man who can't hold his liquor.

Fuck me!............You know how to enjoy yourself on Christmas eve David 😀

Im confused. I'm being taught that when testing IR all loads should be disconnected, certainly sensitive equipment, even when testing between lives and earth. But videos from practicing sparks don't do this.

Hence my CU is full of RCBOs...

Greg Davies' twin😉

Great video, well done, but just realised that my book is a fake as i have no special brew in appendix 5, mine reads Guinness.!!!

I was quoted £220 for that clamp. What did you pay?

a qick tip or a quick tipple lol

shandy shaken not stirred lol

Special brew lol