On 12 Mar 2006 23:06:11 -0800 someone who may be "w_tom" wrote this:-
In the past five years there has been a requirement to fit an RCD to certain things in certain parts of bathrooms. Whether this makes people safer has yet to be seen. Personally I suspect that the improvement in safety will be limited.
Who says it is not a hazard? The fact that the IEE has for a very long time had special regulations about rooms containing baths [1] and showers indicates that it is a hazard.
[1] at one time it was fixed baths and showers, but this was dropped a little time ago after tin baths became largely items of historic note only.
The "hair-dryer picture" referred to in the NIC article is there only as an an illustration of why mains-voltage socket-outlets are still not permitted in UK bath & shower rooms.
Hand-held appliances are now allowed if hard-wired and are in Zone 3 or beyond (> 0.6 m from the bath or shower tray). The supply to a portable appliance in Zone 3 must be protected by a 30 mA RCD. The RCD in this case is providing supplementary protection against electric shock by direct contact. Other than this, RCD protection is not required for direct contact protection - this being ensured by requirements for adequate insulation and for the use of equipment with suitable IP ratings.
Protection against shock by indirect contact (i.e. contact with parts which are live as the result of a fault) is achieved by means of earthed equipotential bonding and automatic disconnection of supply ('EEBADS'). The regulations give design principles which are based on the IEC touch-voltage curve, and seek to prevent the appearance of dangerous voltages between accessible metal parts for an excessively long time. Automatic disconnection of supply here is preferably (and usually) achieved by an overcurrent device - i.e. the rupture of a fuse or tripping of an MCB. However the standard does recognise the use of RCDs for this purpose when the earth fault loop impedance is too high to ensure operation of the overcurrent device - such as where there is no metallic earth path to the earthed point of the substation transformer (TT-system).
In bathrooms and other areas of high shock risk local supplementary equipotential bonding is required to reduce touch voltages further.
Because in nearly all cases, there is no need for them as there is no accessibility to that electricity. Lighting is governed by rules that include the type of safety holder that can be used. Electrical outlets are banned in most zones, except for transformer isolated ones.
But electricity exists in that bathroom. Zones were the old way of safety when RCDs did not exist. A human with wet feet could walk a meter inside that same room and touch something electric - two wire or three wire. And yet somehow that is considered safe? Zones were once considered sufficient protection. But today, the RCD for any electrical light, switch, or outlet anywhere in a bathroom is now considered necessary. 20th Century code requirements, because the technology once did not exist, are not sufficient for 21st Century humans.
The original point posted to the OP. Current technology is now so cheap and so effective that a best solution for all bathroom circuits is the RCD. Low cost of that solution is why that solution has been standard elsewhere for 30 years: all bathrooms electricity provided only by local RCD circuit. The most 'electrically at risk' human is one with wet skin. Not just in a bathtub. Wet skin is when natural electrical protection is severely diminished. Wet humans can be anywhere in that bathroom. Therefore we routinely install RCD devices for any electricity in that bathroom.
I am so surprised that some UK residents would only worry about legalities and not worry about the risk. Any wet human anywhere in that bathroom is at major risk. Any electricity anywhere in a bathroom should be via an RCD device as has been standard in NA for the last 30 years. This because an RCD solution is so effective AND because the protection is so inexpensive.
The original poster jon was asking about electrical safety in the bathroom. RCDs have long been a basic and most well proven solution to electrical safety in bathrooms. Exceed code requirements. Install
21st Century safety - the RCD. Safety standards proven and used standard for decades. Safety standards that still are not standard in the UK where some insist 20th Century safety codes are sufficient.
Any doubt about that bathroom safety? > >> If RCDs do not provide human safety to UK bathrooms, they why? Why
If it was only an assertion, then you responded with technical facts as to why it is not so. David Hansen posted a denial without a single supporting fact or reason. IOW David Hansen posted the assertion - as demonstrated by no citations, no numbers, and no proof that RCDs provide no human safety.
Meanwhile, RCDs are routine in other nations for bathroom safety. This necessary because - just another fact, David - humans are at greatest risk when wet.
But David - show us you have basic knowledge. Show us how the RCD does not protect human life. The > Another series of assertions, with nothing to back them up other
If it was only an assertion, then you responded with technical facts as to why it is not so. David Hansen posted a denial without a single supporting fact or reason. IOW David Hansen posted the assertion - as demonstrated by no citations, no numbers, and no proof that RCDs provide no human safety.
Meanwhile, RCDs are routine in other nations for bathroom safety. This necessary because - just another fact, David - humans are at greatest risk when wet.
But David - show us you have basic knowledge. Show us how the RCD does not protect human life. The > Another series of assertions, with nothing to back them up other
On 14 Mar 2006 01:08:04 -0800 someone who may be "w_tom" wrote this:-
"Mine's bigger then yours" discussions are not my thing. However, I am familiar with BS 7671 and have designed, installed and maintained electrical systems (though only up to 33kV).
An RCD protecting a circuit feeding equipment in a bathroom would not protect someone from the effects of contact with metalwork earthed via different paths which could, due to faults _elsewhere_in_the_electrical_installation_, be at dangerously different potentials. This is why BS 7671 mandates the use of local supplementary equipotential bonding as a primary safety measure.
I thought it was quite funny. Mr Tom, you have made so many errors and missed so much that no-one so far has shown any interest in explaining it all for you. I dont have all day either. If you split up your enquiry into several threads you might possibly get more detailed feedback.
On 14 Mar 2006 09:14:35 -0800 someone who may be snipped-for-privacy@care2.com wrote this:-
Indeed. A number of people have made technical points which remain unanswered, except for slogans that probably came from a sales brochure. Personally I have made no technical points, as others beat me to it.
On Tue, 14 Mar 2006 17:07:50 +0000 someone who may be Andy Wade wrote this:-
And the results speak for themselves. I gather significantly fewer people die in the UK due to the "strict" requirements. This is one of the reasons why the IEE has held out against some changes and I think they are right to do so.
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