Electrical question

zzzjim · Aug 10, 2014

Tell people to be more carefull with those cheap kettles on a base , wet every where when they boil !

Not so much faulty appliance , as customer abuse !

bacon_sandwich · Aug 11, 2014

Best said:
I spoke about this thread to a friend who is an electronic engineer & a top engineer at that & coincidently is about to do new wiring system for his own place.
His take on all this, (& I have removed some of the expletives he made about plumbers & most sparks) was this in an email to me -

"Re RCBOs - as the name suggests, they are a MCB with integral RCD! Good but unnecessary and expensive! A typical MCB is a couple of quid but these are £15-20 each. Not needed if an RCD feeding consumer unit. Only advantage is that if you have a dodgy appliance with earth leakage etc, it will only take down that circuit. Not a fat lot of use if your main ring main etc as you need to find the culprit or you can't get circuit back on until fault removed. Does mean, however, that your lights etc are still on for you to see!!!!
There are idiots who put these on where they have frequent tripping in order to not impact the remainder of house and other idiots talking about leaky appliances and sharing the leakage across a number of RCBOs in order to reduce tripping ( assuming leaky equipment on various circuits). If there is a small electrical leakage in your immersion e.g. It does not mean that it is an old element and acceptable and should be managed better by RCBOs ... It means it needs replaced! Same rules with other (typical element and or water based elements) steam irons, cooker elements (leaking moisture from cooking or elements starting to break down. "

He also later added - " FIX the leakage problem, don't try and resolve by electrical workarounds to minimise or hide the problem!! No leakage is acceptable - after all, how does virtually every household do without any trips?

I totally disagree with this . This guy is not a practicing electrician. Manufacturers are allowed to type test their products with a certain amount of leakage. This is normal and is part of the electrical design. I have, as part of my job using 1000s pounds worth of test equipment proved this time and time again. Computers and servers , electricians know there are only so many you can put on a single RCD before nuisance tripping occurs and it is part of the design to create multiple ccts for offices that have a vast amount of computers. The story I told about the flat was a case in point, all the equipment was either new or very recent, there were no faults but the flat leaked and un-acceptable amount due to a high concentration of electronic equipment. Sorry but the guy is just plain wrong, and I raise his "knowledge" with a BSc 1st Class in electronic systems and control engineering and 34 years working in the electrical field...

lame plumber · Aug 11, 2014

my dining room chandelear has its own lighting circuit, due to its 10 x 100w lamps. It also takes about 5 hours to drop, dismantle and clean and rebuild, so only done it twice!

and dont I winge if the family turns it on!!!!!!

jaydebruyne · Aug 11, 2014

Masood said:
I know some of you esteemed gentlemen occasionally dip into the cesspool that is electrickery so before sullying myself by visiting the sparky forum I'll ask here...

We're refurbishing our rental flat and the electrics are "interesting".

Economy 7 (we want rid of it)
All sockets on one ring (whole property under 100m2)
One circuit for storage heaters (removed a long while ago)
Immersion on it's own fuse
Shower and cooker on one fuse (well over it's capacity)

We are getting rid of fuse board, replacing with modern consumer unit.
Shower getting it's own RCBO
Oven getting it's own RCBO
Hob getting a new spur directly off consumer unit, it's own RCBO
Two new spurs off separate RCBOs for space heaters in bedroom and living room
Various sockets being relocated

We've been told that if we do major works such as a rewire (or have an extension built etc) then the kitchen MUST be on a separate ring to comply with regs.

My question is - does the above count as a rewire? Obviously it's not a full rewire but in my opinion it's a major enough piece of work to count as such and therefore need to comply. SWMBO (degree in electrical engineering) disagrees. no dispute that it's good practice to have a separate ring, but is it obligatory?

I have in mind Part L, and how a number of "component upgrades" ***ulatively become classed as a "system upgrade", necessitating fuller compliance. But I don't know if this applies to electrics as it does to gas & heating...

TIA,
Masood

As far as I'm aware, it's just 'good practice' for a kitchen to be on a separate circuit. And even if your only separating existing circuits, the moment you install a new CU, the BCO rears its ugly head and it all gets compliantly messy!

Also, if you alter an existing circuit in any way, I'm sure it then has to comply with 17th edition wiring regs.

Best · Aug 12, 2014

bacon_sandwich said:
I totally disagree with this . This guy is not a practicing electrician. Manufacturers are allowed to type test their products with a certain amount of leakage. This is normal and is part of the electrical design. I have, as part of my job using 1000s pounds worth of test equipment proved this time and time again. Computers and servers , electricians know there are only so many you can put on a single RCD before nuisance tripping occurs and it is part of the design to create multiple ccts for offices that have a vast amount of computers. The story I told about the flat was a case in point, all the equipment was either new or very recent, there were no faults but the flat leaked and un-acceptable amount due to a high concentration of electronic equipment. Sorry but the guy is just plain wrong, and I raise his "knowledge" with a BSc 1st Class in electronic systems and control engineering and 34 years working in the electrical field...

I am only a messenger here, just passing some of my friends knowledge into this forum. I sent him some of these posts to see what he thought.
You are correct that he is not simply an "electrician". To call him an electrician would only indicate a very tiny part of his qualifications & experience & frankly he was above that level when he had barely started working when young. I don't want to give personal detail out about him, but his credentials are extensive, very impressive & from hands on experience to academic qualifications - often at same time. Very rare to have both. He is actually a very helpful person, despite him being very busy in his profession & always worth listening & hopefully learning from. He is one of us - from an engineering background & he would try to word everything in basic speak for those (like myself) not so knowledgable.

He has come back with this advice to us all -

[ "Lets not carry more assumption into business premises please! ...all more recent homes and very large homes, (never mind small flats ) typically are wired with either single, or in split load 17Ed, dual RCDs. (Or other multiples where additional CU installs for independent electrical requirements, workshops, external power etc with 30ma RCDs. Tripping is not an event that we see due to all this 'electronic equipment and computers.' On the converse the house leakage is typical white goods, steam irons, immersion heaters, cookers, damp ingress or other defective kit, wiring etc - where leakage is high - REAL FAULTS. Manufactures do design and build to minuscule leakage tolerance, but nano amps level, not milliamps. This design tolerance is to allow for minute manufacturing tolerance in electrical products and also to allow for limited inductive and capacitive characteristics ( including RCD and RCBO manufacture,) NOT to allow acceptable leakage in household or business appliances! Do remember that you can occasionally get a faulty RCD, RCBO though, as they come in cheap variants like everything!
Likewise, business equipment must meet the same, very stringent safety and electrical emission test standards.
Offices are wired differently but same principles apply, once again not to get past 'leaky equipment' but in order to allow for the vast fluctuations and spikes in power requirements such as data centres where server racks and associated equipment usage. (Ps ....Failing server internal LV power supply units are the typical cause of tripping, since servers typically run 24/7/365 and are often in environments with inadequate Ventilation/air conditioning, together with fans grills becoming blocked with dirt and dust etc. Once again, the PSUs need replaced - they are faulty..... Don't put on their own RCD in the hope of reducing the fault sensitivity!
If nuisance business tripping is occurring, it is more often current overloading as MCBs on average only allow 1.2X their current rating before tripping. In which case, evaluate the circuit loading and type of load, inductive, resistive etc and resolve with suitable redesign and redistribution. Please, please don't consider tripping as acceptable, nor is it a product of electronic equipment in households.....otherwise all of our houses would be in the dark every night! If your house is tripping, it ain't your Bose. Would you put tinfoil or a screw in a blown fuse...same difference as.
I suggest that 'leaky houses' are being confused with dodgy plumbers and water pipes 🙂

Regards," ]