No, not unless the resistance of the earth path is extremely high, the machine well insulated from the floor and the water pipes not connected.
As Dave calculated and assuming his calculation is correct, it would need to be higher than 8K Ohm.
I'd just like to say 'Thanks!' (again!) for the thoughtful and detailed answers to my questions.
Bill
If the op complained of such a problem I'd agree, but atm it seems to be wo= rk not needing doing.
accepted
Hall table. Stairwells tend to look a bit bleak otherwise, and it solves th= e light failure issue.
Indeed. My point was that even when it is a requirement _for new installs_ = its of close to zero benefit to retrofit it
its not really lowering safety, its leaving a slight chance of near trivial= inconvenience. In practice in situations where either rcd could trip, the =
2nd one will trip at least at some point within a few goes. It wouldn't kee= p me awake at night.It adds nothing imho because what very little it adds is balanced by it cau= sing lights to fail early in a fire when they'd otherwise stay on
Very minor issue, but theyre perfectly ok if you fit enough and check them.= A lot of people don't though.
Its not uncommon, the bearing for the rocker is only plastic on plastic. Fr= equent use roughens it so the rocker will sit in mid position.
Yes. I was thinking more in terms of work involved.
All the op would need do to bring the place upto quite a modern standard, o= ther than simple visual checks, is to replace the 32A MCB and fit a battery= backup light on the stairs. A lot of ukdiy posters could do that themselve= s. With only one socket & one lighting circuit there's little chance of a b= orrowed neutral anywhere.
But even that doesn't need doing, its only optional work to gain the small = safety benefit of moving from an 80s install to a newish one.
NT
That was the point - its a big if. Even if one does look after them, there is still the likelihood that one will have it battery removed for the odd day here and there because a replacement was not to hand.
If the house is inhabited by less sprightly folks, then going for linked alarms with a remote hush and test capability makes sense if they would otherwise be inaccessible on high ceilings etc.
The rocker position on that vintage of switch should not really matter. They will have a bistable biased snap effect mechanism that is driven by a spring - so the switch snaps to one position or the other - the rocker provides the impetus but does not actually drive the switch dolly position itself.
(I am aware of switches that will behave as you suggest - but the are typically a good deal older than 30 years)
There is a bit more on a whole swap - but not much if you are going to do proper tests on each circuit as you go. (keep in mind there are only two circuits at the moment!)
Need is a relative thing - much depends on the occupants and can even come down simply to peace of mind. If they are worried that the present RCD may not work, and they know it will not protect them from a injury should they get a shock, then there may be good value *to them* for the upgrades even if in absolute terms the benefits are marginal.
I agree that a competent DIYer could make big improvements to the system at minor cost, even if they don't comply with the current regs. Much would depends on the ability to get suitable accessories for that model of CU though. If DIY is not an option, then doing work to a indeterminate standard is less likely to be possible.
Some years ago I called at a friend's house to take him out. His locking up of the house procedure included rubbing his finger across each and every light switch to make sure that it wasn't 'half on'. That, incidentally, wasn't the only OCD symptom he had, but that's another story. Later when he'd had a few drinks I broached the subject. Apparently when he'd been a kid the switches in his parents' house were such that it was possible to carefully put the rocker midway, causing the light to flicker and the switch to crackle. The devil finds work for idle hands, as they say. One day his dad realised what he was doing and warned him that 'the wires under the floor will get get red hot, and the house will burn down.' Half a century later when the OCD became serious this little bit of conditioning saw its chance and took hold. I reassured him that there was no way a light switch that was half way could cause any kind of a problem, and he agreed that in any case it was virtually impossible for the switches in his house to rest half way ? but 'one did, once, I think...' Was I right to say what I did?
Bill
The arcing will certainly damage the switch in time, and will cause it to get hot. Its less likely to heat up the wires themselves other than in immediate proximity to the switch. Its a (small) fire risk especially if the old switch is on a combustible wooden pattress or in a wood lined surface recess.
I suppose if the light in question was a particularly reactive load then you might be able to draw a stream of relatively significant peak current switch on surges that would cause heating, but the thermal trip mechanism of the MCB should respond to that before cable damage results.
You can't normally get modern switches to do that (unless they are actually broken) (and by modern, we are talking pretty much any of the flate plate type with a rocker rather than a more "switch" shaped toggle). It probably would not do the lamp any favours - especially if it was anything other than a normal GLS bulb.
What area is it?
T'other side of Donny.
Bill
email me.
I went and checked one today, one of the modernish white square ones. At on= e position it does indeed arc, making a worn rocker a risk. I'm familiar wi= th how switches are constructed; at a certain rocker position on sprung swi= tches there's equal pressure on both sides of the moving switch contact, so= no pressure on the contacts to keep it conducting well. The sprung mechani= sm in modern mains switches much improves the situation compared to the old= round black ones, but it doesn't eliminate it.
Numbers help, with over 100,000 deaths per annum caused by what food one ea= ts, and just a few from electric shock, mainly from people playing the fool= , its probably better to spend the time & money elsewhere.
NT
Oddly numbers don't often help when dealing with people's fears - they are often not rational in the first place, so you can't logic them out of an illogical position.
Having said that (and we have had the conversation many times), focussing on death as the only bad outcome is ridiculous. From the victim's point of view, its the one option that is certain to not have ongoing consequences. While I don't necessarily buy the ESC's figures on shock injury (given their paymasters), even if their claim for 200,000 hospital admissions / year[1] for electric shock injury are wildly inflated, that is still a huge number of people who would be spared the experience by a working RCD. They also claim that government estimates (and we know how good those are!) predict 4,000 electrical fires / year would be averted with RCD protection in the CU.
[1] They also mention or 1.2 million significant injuries / 5 years. Then again they also mention 70 deaths a year which seems to contradict totals from other sources. (They may be including the 22 killed in fires caused by electrical appliance misuse)
Its not about soothing fears, its about surviving and minimising non-fatal suffering.
Over 100,000 deaths versus a handful is far from a ridiculous comparison, it shows where the risks lie, and where benefit is most obtainable.
Re non-fatal bad outcomes, there are plenty of those on both sides, far more of course from poor diet than from shock. I'd far rather have a shock than live with the medical consequences of a lousy diet for years.
ISTR the admissions are for shock rather than injury. Even if I don't RC, there are still far more nonfatal results from poor diet, and the suffering goes on for longer.
Certainly. And with the equally carefully considered same spend on food (perhaps on a soup maker or something) a far greater number of miseries can be prevented.
If 69,000 fires a year cause around 450 deaths, 4000 fires cause around 26 deaths a year. A tiny number compared to the lives that can be saved by improving one's diet, its orders of magnitude smaller.
And the property already has RCD cover, so those fires don't come into the picture, so its even more one sided.
NT
Its about both. Fear alone causes ongoing suffering. You only need look at those suffering stress related illness in Chernobyl due to the fear of health complication from radiation exposure, rather than actual health complications from radiation exposure.
Can you make a lifetime improvement to the quality of food you buy for the one off price of an RCD?
There are plenty of ways one can suffer injury. Some are random and difficulty to mitigate, others such as diet and exercise require a lifetime of cost and attitude adjustment. A few are trivial to fix for a moderate one off payment. I don't see the logic for not fixing the easy ones when the opportunity presents itself, just because there are more dangerous things out there you can't fix as easily.
You can make the same arguments for any number of other cases. The NHS kills 5000/year, RTAs another 3600 etc. If there was a choice between spending £100 on your car with the knowledge that it would make for a significant reduction in injury risk if you are involved in an RTA or spending it on your CU, then sure, spend it on the car in preference. Alas its not so easy with a car. However at least with cars when enhancements do come along that do introduce a step change improvement in survival chances (airbags, ABS, disc brakes, radial tyres etc) you at least know they will work themselves into the national car stock in a fairly short space of time.
While poor diet is certainly a problem, its a straw man.
Its a novel approach to risk assessment. Have you got smoke alarms and RCDs? No, but its not a problem, I have fresh soup!
I think you may be joining different sets of unrelated stats there. The
26 deaths were from fires started by the misuse of electrical appliances. (I only mentioned that, since their total of electrical deaths were higher than the normal government figures). They gave no figures for how many actual fires out of the total of house fires caused those deaths though.The 4000 figure is the projected reduction in house fires achievable by fitting a RCD protection at the CU is all properties that don't have one.
You are conflating general case and the specific arguments here...
Yes, this particular property has RCD protection. That will provide the enhanced fire protection that some properties lack. The RCD in question will not always provide shock protection though due to its trip threshold. In addition there are the many other issues already discussed.
To take one example, an emergency light is cheap and easy, and brings a significant reduction in the risk of a trip or fall (which as you know is a significant cause of injury in the home). Its better than a table lamp since it works in a power cut. However its on par with properly fixed hand rails where they are needed, re-fixing the lose carpet on the stairs, or educating the children not to leave toys on the stairs.
(If you have never lived out of town without street lighting, don't underestimate how just how difficult it can be to navigate round a house with a power cut when its so dark it makes no difference whether your eyes are open or closed)
Really I don't agree. I'm interested in the real issues. (What one fears is= down to education and how one handles thinking etc.)
No, no need to. If the same spend got me a fresh soup every other day for 1=
0 years, that would increase life expectancy more than an RCD. (Add the tim= e it saves and its a bargain.)Its a bit more complex than that, sometimes spending can change attitudes. = If you gave 100 people soup machines, some would change their eating habits= long term because of it, some wouldnt.
Estimates time: If 25% make that long term change, and doing so is 20% of t= he changes needed, thats a ballpark estimate of 5% of 100,000 =3D 5000 deat= hs per yr avoided. Far in excess of the 26+8 annual deaths RCDs could avoid= . Its not a difficult choice.
That isn't the situation though. Getting a spark in to renew the CU would c= ost the OP more than a soup machine, and be more hassle.
No, there are several factors in vehicle choice.
I so don't agree. I'd say if anything the rcd is a red herring for someone = looking to improve their safety, simply because one can achieve over 1000 t= imes more by putting the time money and attention into the real risks. Its = a form of denial.
Not in the least
Amusing if one assumes the real risks are fire and shock, as many do. But i= n reality something as basic as fresh soup saves more lives.
The I 26 mentioned are 4,000/69,000 x 450, ie the number of deaths those 40=
00 fires could be expected to produce.Not really, I'm sure we can address both cases without any difficulty.
NT
OK. I'll wait until I've spoken to them and told them what I've found out, then I'll know how they feel about it. Should see her this weekend, if she comes over to see her dad.
Bill
That was what I meant by joining unrelated stats. The 26 deaths were not from house fires of electrical origin (there were more than that when you include fires started by electric cooking and heating equipment). They were from those resulting from misuse of "other" electrical appliances (i.e. not including cooking, space or water heating appliances).
As an aside, updating some of the other fire stats (and concentrating them into one article) in the wiki would be worthwhile, from:
From Table 2.1 page 34
Biggest single cause being cooking appliances with 19k6 (it does not say how many of those were soup makers! ;-))
Other electrical appliances 4k8 (although that probably includes "set fire to the curtains with hot air paint stripper" type of causes.
4k for electrical distribution.2k7 for smoking related.
195 for blowlamps and welding - DIYers take note!37% of fatalities result from fires starting in the living or dining room, vs only 18% for those in the kitchen. While 60% of non fatal casualties arise from kitchen fires.
Smoke alarm failures: where smoke alarms were present, they failed to operate in 27% of cases. However that was made up of 38% of battery alarms failing compared to only 19% of mains ones. (main cause being missing or flat battery in the first case, and combustion products not reaching the alarm in the second)
No problems if you do need me. Although the next three weeks are fully booked up.
I thought the primary purpose of RCDs was to reduce the risk of electric shock, as opposed to fuses & circuit breakers for fires.
Adam Funk explained on 16/11/2012 :
They serve both purposes. They tend to detect early signs of faults occurring in an installations and equipment. They do not prevent electric shocks, what they do do though is limit the damage or time of exposure to a shock, you still would get a shock.
Its both - although you might select different trip ratings depending on the need. 16th edition TT installs would need a RCD on all circuits for fire protection since you could not guarantee that an earth fault would ever get disconnected by a fuse or MCB[1]. So it was common to use a whole house RCD with a 100 or 300mA trip since that would give adequate fire protection but a very low likelihood of nuisance trips. You would then augment it with a cascaded 30mA RCD for shock protection on the circuits that particularly warranted it.
(17th edition TT installs installs have the same need, but the requirement to use 30mA RCDs on most circuits dictate that a sensible design will use more RCDs than previously to maintain low probability of nuisance trips)
TN systems also benefit from enhanced fire protection from RCDs although there is not the same absolute requirement, since in many cases the fuse/mcb will ultimately do what is required. The RCD will typically achieve disconnection with much lower levels of power being dissipated in the wiring system though.
[1] Imagine a hard short to earth on a 32A circuit where the earth connection has 10 ohms of resistance. You would get a fault current of only 23A - not enough to trip the circuit breaker, but adequate to dissipate over 5kW of power in the earthing and wiring system.HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.