18th Edition Changes

[morqthana]

Yes - the point I was making is that you pick a dimension X that aperson may be stood in the bath and touching and able to touch a light fitting then you calculate the max dimension the bottom of the bath would be from the floor and add them together and you get a dimension that puts all light fittings out of normal reach.
If that works out at 2.25m then all well and good youve solved it - unless someone makes a bath that has extra long legs or mounts it on blocks then you need to add an amount to compensate for that because it effects the reach of the touching.

Who says/where does it say that you have to do that?

 

[ebee]

I think it is based upon limits of normal reach?

 

[Murdochcat]

The only problem with that is peoples height and reach can vary enormously

It’s these sorts of stupid regs that totally undermine the whole point of BS 7671

 

[morqthana]

I think it is based upon limits of normal reach?

That may be how they came up with the 2.25m extent in the first place, but that it not the methodology which is to be used in each and every case to possibly override it.

 

[securespark]

I think it is based upon limits of normal reach?

Arm's reach was introduced in the 15th in 1981.

Definition: A zone of accessibility to touch, extending from any point on a surface where persons usually stand or move about, to the limits which a person can reach with his hand in any direction without assistance.

Reg 412-10 gave a diagram explaining arm's reach, but basically, it was 2.5m; 1.25m for each arm.

Hence the rule that if you had a shower cubicle in a room other than a bathroom, any sockets had to be at least 2.5m away.

Also, parts of a lamp holder within a distance of 2.5m from a bath or shower enclosure had to be "constructed of or shrouded in insulating material." B22 lamp holders had to be fitted with a protective shield to BS 5042, otherwise known as a HO (Home Office) skirt. Unlike the normal shade ring, these were flared. Still seen today on batten lamp holders, they were also fitted to pendants. IDK if anyone has ever seen a pendant in a bathroom with a HO skirt! I've seen plenty over the years.

We never questioned it in college, but I guess you didn't need one if you had an E27 lamp holder, not that they were common back then.

As an alternative, the reg said, an enclosed fitting could be used.

 

[ebee]

I do mot reckon that either 2.25 or even 2.5 metres could reasonably place all to all persons out of all reach, I think instead they tried to pick a reasonable figure that would tend to deter most of the population that might act fairly normal-ish by not making it as reasonably touch ease as would otherwise be the case.
A compromise like most things in life/
You look at you might reasonably expect, than perhaps add a margin more but you do recognise that there still some individuals who will do slightly to grossly absurd things however much you might add on.
What can you reasonably do.

In the case I described with unusually long bath legs or a bath sitting on blocks, if I were using the most important inspection tool of all (The Mark 1 Eyeball) I would make a sound engineering judgement that the effective standing level of aperson stood in the bath is higher than "normal" and therefore is that amount sufficient to cause concern and if so the to what degree of concern would that be?
Hopefully a pretty good judgement but can I say I would never get that wrong? No!

Long gone are the days when I see a situation and then think "Well I never would have expected anybody to do that!"

I have had instances were some Electricians , even of long standing but often in industry not domestic service or not much domestic service experience, make that expression and sometimes add "but you knew straight away, how come?" . Maybe it`s just because I have been in more houses to notice what sometimes gets done and more often than you might ever guess - "there`s nowt as queer as folk" is a true expression sometimes.

 

[securespark]

In the 15th Edition, there were no bathroom zones. In fact, "safe" zones for cables had only just been introduced (523-20). There were no diagrams for safe zones and no OSG (these came with the introduction of the 16th.

Even with the introduction of BS 7671 in 1992, there were no bathroom zones. The regs were still running with the idea from the 15th, ie Arm's reach, 2.5m. it was only part way through the 16th Edition that bathroom zones were born.

Before the introduction of bathroom zones, the idea of Arm's reach was to prevent anyone in a fixed bath or shower from coming into contact with any electrical accessory, except for an isolating shaver socket and pull cords of switches and instantaneous water heaters.

Having written that, the reg goes on to say that electric heaters with elements accessible to touch must not be installed within reach of a person using the bath or shower.

The regs did allow lamp holders to be within arm's reach but they had to be constructed of or shrouded in insulating material. Plus, if the lamp holder was a B22 type, there should be a HO skirt fitted.

I think 2.5m is sufficient.

My span is significantly more than my height, which is unusual, and I'm just over 6 ft.
But it's nowhere near 2.5m!

 

[pete01]

The 2.25m rule must work as no one ever gets electrocuted in the bath (ish)

If the height was 2m people would be dying much more (not)

 

[Ragnar_AT]

I seem to remember that the maximum arm span (fingertip to fingertip with the arms stretched out) is usually roughly equal to the person's height, give or take a few cm (for me it's about 50 mm off) so 2.5 m seems to err quite far on the side of caution. Also wasn't the minimum distance of sockets from the bath/shower originally 3 m and reduced to 2.5 fairly recently?

 

[securespark]

I believe so. But since the 15th, 2.5m has always been the (minimum) distance sockets must be when there's a fixed shower in a room other than a bathroom.

I always thought it was odd that they decided on 3m for bathrooms.