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Topic Title: Bathroom zone 1
Topic Summary: flawed in design ?
Created On: 25 January 2013 10:03 AM
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 25 January 2013 10:03 AM
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Avatar for redtoblackblewtopieces.
redtoblackblewtopieces

Posts: 208
Joined: 10 January 2013

This question first came to life in my mind with the demise of zone 2 above zone 1 with bs7671 2008 and has since resurfaced with the up and coming changes to Part P of the Building Regulations regarding works outside zones ( alterations and additions) being non notifiable.
Should the ascending 2.25m height level of zone 1 start not from finished floor level but from the level where a body could be expected to stand on the surface of a bath or shower tray ?
This level can be as much as 30cm from installations which i have seen and with low ceilings put items of installed electrical equipment which if measured from FFL would be classed outside of the zones much closer to a wet body with low resistance than section 701 seems to limit.I am sure all reading this would design the installation and choose equipment accordingly, however sometimes the general public need protecting from themselves.

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Edited: 25 January 2013 at 10:43 AM by redtoblackblewtopieces
 25 January 2013 11:01 AM
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aligarjon

Posts: 2926
Joined: 09 September 2005

i see your point, but shouldn't we as professionals be fitting electrical equipment suitable for the envirement that we are installing them.

Gary.

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Specialised Subject. The Bleedin Obvious. John Cleese
 25 January 2013 11:28 AM
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Avatar for redtoblackblewtopieces.
redtoblackblewtopieces

Posts: 208
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Yes Gary we should and I thought I made that point but joe public in screwfix or b&q or your cash jolly jobber might not and in fact might argue that as measured from FFL its ouside the zones.
Kevin.

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 25 January 2013 11:48 AM
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Avatar for OMS.
OMS

Posts: 19900
Joined: 23 March 2004

Given that we have RCD's and effective bonding, is it really a risk.

Consider a luminaire that's outside of Zones but suitable for the location - it may be class 1. Even standing in an elevated shower tray, such that the luminaire is touchable, there is unlikely to be any component that could be gripped sufficiently such that a convulsing body would remain in contact - ie the collapse would break contact.

Joe Public is quite safe - there is more risk from a BC lampholder and a dining chair to be honest.

The RCD in the bathroom actually provides some protection against user stupidity - we can't save all the idiots all the time

Regards

OMS

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 25 January 2013 11:50 AM
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AJJewsbury

Posts: 11784
Joined: 13 August 2003

Nothing's perfect. The zone's don't take account of the different heights/reach of people. Someone who is 7' tall isn't going to get the same level of safety from the zones as someone who's 5'2". Bath base height is just the opposite end of the same stick. I guess they just have to consider what would be OK in the majority of situations, build in a bit of a margin, and hope people will apply a bit of (engineering) judgement for really unusual circumstances.

If we had it measured from the bottom of the bath then there'd be the problem on new builds etc if the electrics were done before the plumbing - that there wouldn't necessarily be a bath present to measure from. Plans will give you the (intended) position of the bath, but not usually its internal height.

- Andy.
 25 January 2013 12:50 PM
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Avatar for redtoblackblewtopieces.
redtoblackblewtopieces

Posts: 208
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Dear OMS by your post does that mean ip ratings and zones are a waist of time:-) if the installation had no rcd protction for the lighting circuit ie an earlyer addition installation would said joe public fit one? Still I take both, your points on board and will let it lie.
Kevin

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Safety through a Standard
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 25 January 2013 01:37 PM
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Avatar for OMS.
OMS

Posts: 19900
Joined: 23 March 2004

Originally posted by: redtoblackblewtopieces

Dear OMS by your post does that mean ip ratings and zones are a waist of time:-)

Did I say that ? - I was simply pointing out that the risk as you perceive it may be just a little lower in reality. The IP rating and zonal system are based on a simple broad assessment of risk - you or anyone else should not read into it that everything inside zones is lethal and everything outside zones isn't - the boundary is somewhat arbitary.

if the installation had no rcd protction for the lighting circuit ie an earlyer addition installation would said joe public fit one?

I guess that depends on the advice they receive from thier advisor - although I don't recall the provinces bathrooms being littered with corpses over the last few decades

Still I take both, your points on board and will let it lie.

You can let it do what you like - it's just a debate where I offered an opinion on your postulated threat to Joe Public

Kevin


Regards

OMS

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Failure is always an option
 25 January 2013 04:25 PM
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Avatar for spinlondon.
spinlondon

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To my mind, if the installation complies with an earlier edition, then whilst there may be no RCD protection for circuits of the location, there would have been at the time of construction a zone 2 above zone 1.
I would expect that the requirements for equipment in zone 2 to have been met.
Stands to reason I suppose, if the installation complies with an earlier edition.
As far as the change in Part P is concerned, there is no real change, other than the extent of the special location (as defined by Part P) has now been included in the approved document.
Why this information was not in the document before and why it has been included now, is anyone's guess.
 27 January 2013 07:18 AM
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ebee

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Actually a few years ago I did ask the IEE the same question ie not measuring from finished floor level but bottom of bath or shower basin where a person might reasonably stand level.

I was disappointed with their reply of finished floor level.

I suppose that if someone mounts a bath on a plinth or fits longer legs then a rethink is in order

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Ebee (M I S P N)

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