Disconnection Time

[Ahr35181]

In the UK, what is the required earth fault disconnection time for fixed equipment in a special location (e.g. bath / shower room)?

Being within the equipotential zone, is it 5 seconds, or is it 0.4 seconds because it’s high risk location?

Thanks,

Alan

 

[Sparkyman]

Part 6 of BS7671, Requirements for Electrical Installations states:-
Section 601,
Part 601-04-01
Except for SELV (Safety Extra Low Voltage) for a circuit supplying equipment in a room containing a fixed bath or shower where the equipment is similarly accessible with exposed conductive parts of other equipment or with extraneous conductive parts, the characteristics of the protective devices and the earthing arrangements shall be such that, in the event of a fault to earth, disconnection occurs within 0.4 secs.

You need to read the whole of Section 601 because it talks about equipotential bonding and lots of other things.
Regards

 

[Ahr35181]

Sparkyman,

Thanks for your reply, I thought I'd noticed this in BS7671:2001 previously, but when I looked to reconfirm the other day I couldn't find it!!

Thanks,

Alan

 

[ScottyUK]

Sparkyman,

I nearly posted the same extract from the regs... but it isn't there in the 3rd Amendment to the 16th Edition regs. Section 601 has been completely re-written.

 

[Ahr35181]

ScottyUK,

That's why I couldn't find it!!

I'll contact the IEE tech support to see if it still applies,

Thanks

Alan

 

[Ahr35181]

The following is a reply from the IEE:-

There is now no reduced disconnection times for fixed equipment in bathrooms, as such. There are requirements for 30 mA RCDs for certain items of equipment dependant upon the zone.
Showers have a 5s disconnection time.


So electric showers no longer require a 0.4 second disconection time & STILL DO NOT REQUIRE RCD PROTECTION!!!

Alan

 

[ScottyUK]

Thanks Ahr35181,

I wondered about this a while ago, and played safe with 0.4 s disconnection time.

I guess showers don't need the RCD because they have an earthed copper vessel enclosing the elements, and the elements themselves have an earthed sheath.

Very useful to know about the IEE's technical help service, I'll store that away for a future date.

 

[Sparkyman]

Whoops!!

There's only one thing for it,

Dear Santa,
'Cos I've been a good Electrical Engineer all year,
Can I have a nice new Blue copy of the Regs please.
Thanks
Sparkyman

 

[panelman]

the niceic technical book covers all this sort of stuff and well worth getting

free to members....i think non members can get a copy for a few hundred pounds

 

[Ahr35181]

panelman,

£400 I was informed!!!

I'll have to stick with my blue copy of BS7671, which I received last Christmas day!! & the guidance notes.

I would have to be a really good lad for my boss to splash out that kind of cash!!

Alan

 

[panelman]

i'd say it's worth it even at that price but....

ssssshhhhhh don't tell anyone but it's coming out on cd soon, when it does perhaps someone could burn you a copy