Please ensure your electrics are up to date!!!!!!!!!
Comments
-
Yes, you could touch both taps - but you could also just touch one tap, the other connection being the metal bath (or plughole surround via the water) that you're sitting in - unless they are equipotentially bonded. I agree that the possibility is small, but anyone who's contacted the mains with wet hands will confirm that it's a lot nastier than with dry hands.
By the way, you don't want circuit breakers to trip too quickly or you'll get nuisance trips from surges etc. So you have to compromise. Generally speaking, MCBs are designed to protect against fire from overloads (they will not trip from the relatively tiny current that can kill a person) and RCDs against shock (because they measure current flowing through a different path, so they can ignore the current that is supposed to be there while still detecting tiny unwanted currents).Time is an illusion - lunch time doubly so.0 -
No way! I'd never fit a board fully populated with RCBO's. They are nothing like as cheap as 2 x RCD + 10 MCBS.
Look at TLC Wholesale for a good comparison;
MK
2 x 60A 30mA RCD @ £41.50 ea. + 10 x MCB @ £2.50 ea. = £108
10 x RCBO @ £ 24.95 ea = £249.50
Wylex
2 x 63A 30mA RCD @ £23.55 ea + 10 x MCB @ £2.99 ea = £77.00
10 x RCBO @ £25.00 ea = £250.00
Hager
2 x 63A 30mA RCD @ £14.95 ea + 10 x MCB @ £2.75 ea = £57.40
10 x RCBO @ £21.95 ex = £219.50
Contactum
2 x 63A 30mA RCD @ £14.50 ea + 10 x MCB @ £1.99 ea = £48.90
10 x RCBO @ £18.99 ea = £189.90
Cost per circuit with all RCBO's is at least 2.3 times as much as using RCD/MCB, and up to 3.8 times - using my examples above.
Comparable? - my !!!!!! (with all due respect
) Similar price difference at all my suppliers/wholesalers.
You are looking at the most expensive brands (Contactum have gone bust btw) which is never gonna work out.
And I said 'comparable' not 'identical'.
The price differences are not as big as you are making out. For a start, you are quoting prices for 2xRCD+10xMCB rather than a Dual RCD Consumer Unit.0 -
Not that it would have helped this gent, because he was presumably not expecting to get an electric shock. But when I was an electrical apprentice in the 1950's we were told that if there was the slightest doubt about something being live, that you should touch it for the first time with the back of your finger. If it was live, then the shock would make your hand clench and this would move your hand away from the source of danger. If you clench it, as the chap in the quote did, then your hand will grip the live object and you cannot remove it. Even today, and even though I know that I have isolated and tested, I still do the first touch with the back of my finger.Mary_Hartnell wrote: »Thanks, I think I can understand this is in the aged of almost instant circuit breakers. Could be interesting if one pulled oneself up using the two metal bath taps if both were fed by copper pipes and one had become live and the other had not.
I must admit I have never felt insecure in my 1970 bathroom, with none of this protection (just one big slow clunky breaker on the company side of the fuse box, probably stops the house burning down but might not save someone with a serious shock through their body. (When I moved in a found someone had put hair pins in the 4 fuses that serve the whole house !).
In my previous house of 1950's vintage, we nearly had a widow next door: hubby had a bit of a dodgy drill (they were metal in those days). He was up a ladder, drill in one hand trying to fit plugs to take a curtain rail. In those days retro fitted central heating nearly always had the two pipes running down behind the curtains.
So he used the other hand to get extra purchase by pulling on the pipes.
Wife found hubby, with tongue sticking out, in a pool of water - husband supercharged by electricity running to earth from drill to pipe, had performed a bear hug manoeuvre and ripped the radiator pipe off the wall.
:eek:
:eek:I can afford anything that I want.
Just so long as I don't want much.0 -
dwarvenassassin wrote: »You are looking at the most expensive brands (Contactum have gone bust btw) which is never gonna work out.
And I said 'comparable' not 'identical'.
The price differences are not as big as you are making out. For a start, you are quoting prices for 2xRCD+10xMCB rather than a Dual RCD Consumer Unit.
I still disagree! I took the bare bones CU (main switch only) out of the equation and just compared the guts, 2 x RCD +10 x MCB vs 10 x RCBO, seeing as you wouldn't buy a dual RCD CU and fill it with RCBOs!! It's the same base cost whatever you put in it and therefore doesn't affect the argument. Buying a dual RCD CU only makes it even cheaper - QED.
Even with the "budget" brands (some of which I wouldn't touch with a barge pole {cough, CTI, cough}
) the price difference is still significant. I couldn't get closer than 1.6 times the cost at any of my wholesalers, regardless of brand, which doesn't fit my definition of "comparable"! Heck, even with Q Line stuff you are looking at £42 vs £149.50!! How is 2 x £12 + 10 x £1.85 (£42) "comparable" with 10 x £14.95 (£149.50)? It isn't.
Asking around my fellow sparks, and on various sparky forums, none of us would ever populate a CU with RCBOs, not just because of the silly cost (which customers won't stand for) but also because a board full of RCBOs is a right old rats nest and a !!!!! to work on, seeing as there are two extra wires per circuit! That's what dual RCD boards are for !!!!!!, so you don't have a board full of RCBOs. Stick one or two in to protect otherwise unprotected circuits in a split load board perhaps, but why fill a CU with them? - nothing gained except cost and complication.0 -
...ignored the fact that the enclosure on Dual RCD boards is more expensive than a 'standard' enclosure.I still disagree! I took the bare bones CU (main switch only) out of the equation and ...
You are missing the point, we are comparing complete Consumer Units rather than contents.How is 2 x £12 + 10 x £1.85 (£42) "comparable" with 10 x £14.95 (£149.50)?
That's funny, because all the professional electricians I speak to prefer this method. These "sparky forums" wouldn't be places like Screwfix would they?Asking around my fellow sparks, and on various sparky forums, none of us would ever populate a CU with RCBOs
So, if customers wont stand for it can you explain why it now being specified in tenders?not just because of the silly cost (which customers won't stand for) but also because a board full of RCBOs is a right old rats nest and a !!!!! to work on, seeing as there are two extra wires per circuit!
As for it being a rats nest, it should not end up in such a mess if you take time and care in you are doing.
Nothing gained? Riiigghhhhtt. So there is absolutely no benefit from having one RCD per circuit then?That's what dual RCD boards are for !!!!!!, so you don't have a board full of RCBOs. Stick one or two in to protect otherwise unprotected circuits in a split load board perhaps, but why fill a CU with them? - nothing gained except cost and complication.
"Stick one or two in to protect otherwise unprotected circuits"? So can you show me an average domestic installation that does NOT require RCD protection on EVERY circuit under BS7671:2008?
As for splt-load twin-RCD boards, they were brought in as a 'work-around' for the 17th back when RCBOs WERE extortionate. They are far from ideal and only just within the requirements of regulation 314.1 - 314.40 -
dwarvenassassin wrote: »...ignored the fact that the enclosure on Dual RCD boards is more expensive than a 'standard' enclosure.
You are missing the point, we are comparing complete Consumer Units rather than contents.
And? Seeing as you like cheap kit, lets compare some cheapo stuff from Q Line then, 12 way dual RCD CU + 12 MCBs vs 12 way CU with 12 x RCBO.
12 Way insulated dual RCD board c/w 2 x 80A 30mA RCD, £60
12 x MCB @ 1.85 ea, £22.20
Total £82.20
12 way Insulated CU, £18.00
12 x RCBO @ 14.95 ea, £179.40
Total £197.40
So £197.40 is "comparable" to £82.20 then? Show me an example where they are comparable (within, say, 10%) if I'm so wrong - I don't think you have yet, have you?That's funny, because all the professional electricians I speak to prefer this method. These "sparky forums" wouldn't be places like Screwfix would they?
No need to be facetious just coz you're wrong! Screwfix, pah, don't insult me - I thought we were both professionals !!!!!!. After asking around, again, still not one sparks I've spoken to seems to agree with you.
The sparky forums I frequent are electriciansforums.co.uk, theiet.org/forums, talk.electricianforum.co.uk, any of them seem familiar?So, if customers wont stand for it can you explain why it now being specified in tenders?
Not many of my domestic CU change customers send out tenders, nor do any specifically request a CU full of RCBO's.As for it being a rats nest, it should not end up in such a mess if you take time and care in you are doing.
Still 2 extra wires per circuit, which can be avoided.Nothing gained? Riiigghhhhtt. So there is absolutely no benefit from having one RCD per circuit then?
Ok, perhaps some potential nuisance tripping annoyance is avoided, but that's all, and at what cost?"Stick one or two in to protect otherwise unprotected circuits"?
In an existing split load CU, for example if separating/adding circuits so a new bathroom install is RCD protected then I might add an RCBO into the existing CU, but NEVER in nearly 30 years have I fitted a new CU and filled it with RCBO's, it's overkill to the extreme (and cost!).So can you show me an average domestic installation that does NOT require RCD protection on EVERY circuit under BS7671:2008?
Apart from those millions that were designed/installed before 1st June 2008?
You know as well as I do that BS7671:2008 is not applied retrospectively, so only if doing a CU change might all circuits need to be RCD protected. Of course, any new works/circuits (where cable is not buried 50mm etc.) and those in special locations have to be RCD protect.As for split-load twin-RCD boards, they were brought in as a 'work-around' for the 17th back when RCBOs WERE extortionate. They are far from ideal {In your opinion, but yet the IET seem fine with them}and only just within the requirements of regulation 314.1 - 314.4 {yes, I have the big red book too}
Regardless of your opinion, there are plenty out there, they do a job, meet the regs and are used by just about everyone (except you, apparently). A 5+5+2 board is ideal, gives 10 RCD protected circuits, so you can split lights/rings up/down across separate RCDs and minimise nuisance trip annoyance (and meet design rule regs), and 2 spare ways for you to put your beloved RCBOs on, if appropriate.
Now have we done with this "peeing up the wall" contest?0 -
My brain hurts0
-
I am currently asking for quotes for the total rewiring of the electricity supply in my home. The current wiring is about 45 years old and it is not earthed (PME'd). Central Networks (New Connections) will do the latter for £151.63, but a qualified electrician will earth it for £60.00. When I discussed the difference in price with New Connections I was told that the independant electrician would not have access to the sub station or the necessary PME box . This is all new to me and I will appreciate any advice offered.
Regards,
Emrys Davies.0 -
emrysdavies wrote: »I am currently asking for quotes for the total rewiring of the electricity supply in my home. The current wiring is about 45 years old and it is not earthed (PME'd). Central Networks (New Connections) will do the latter for £151.63, but a qualified electrician will earth it for £60.00. When I discussed the difference in price with New Connections I was told that the independant electrician would not have access to the sub station or the necessary PME box . This is all new to me and I will appreciate any advice offered.
Regards,
Emrys Davies.
I think you are a little confused with your terms. Are you saying that you do not currently have any earth connection supplied to your premises?
PME (Protective Multiple Earth) is another name for a TN-C-S supply from your local DNO (Distribution Network Operator) - it is a supply which has several connections to "the mass of earth" between you and your local substation, hence Protective MULTIPLE Earth. The DNO is responsible for the supply infrastructure and NOT the people who supply you with electricity.
Depending on where you are, and the current method of supply, they may provide a PME'd earth but they may also suggest that you employ an electrician to provide a local earth connection by way of an earth rod. They should come to survey and decide on the most appropriate method of providing an earth (although you should be aware that, surprisingly, they are under no obligation to provide one!)
This is not something an electrician can deal with, it has to be done by your DNO. From what you've said it's probably EON:Central Networks, but if not look at this list to find out who yours is;
http://www.nationalgrid.com/uk/Electricity/AboutElectricity/DistributionCompanies/
Once you have an earth connection provided (or if they tell you to fit a local earth rod) then an electrician (like me) can come and rewire your premises with cables which include a CPC (Circuit Protective Conductor or earth wire -usually by way of twin & earth cables) to meet the regulations.
Are you fed by an overhead cable by any chance?
Could you take a photo of your current supply head (end of supply cable and meter) and then we can tell you what your current supply is. (TN-S, TN-C-S (PME), TT etc.)
More about different supply/earth systems/types here;
http://en.wikipedia.org/wiki/Earthing_system0 -
A very informative post above.
I have what must be a TT system supplied by two "overhead" thick aluminium wires, which I share with one neighbour.
It dates back to the 1960's and is so simple that even I can understand it:
4 Fuses of the wire variety that vaporise if there is a short circuit.
A big brown sliding switch that describes itself as "Henley 60 amp earth leakage circuit breaker".
The latter gets temperamental if there is a fault developing (EG if the insulation of a lighting socket has been perished by the heat from the bulb) AND one time when the neighbour installed a compressor that caused electrical surges on our shared overhead wires.
These days the "cupboard in the garage wall" of modern houses seem to have as much wiring as the Star Ship Enterprise.
Am I missing out on something?0
This discussion has been closed.
Categories
- All Categories
- 343.1K Banking & Borrowing
- 250.1K Reduce Debt & Boost Income
- 449.7K Spending & Discounts
- 235.2K Work, Benefits & Business
- 607.9K Mortgages, Homes & Bills
- 173K Life & Family
- 247.8K Travel & Transport
- 1.5M Hobbies & Leisure
- 15.9K Discuss & Feedback
- 15.1K Coronavirus Support Boards