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Topic Title: Kitchen splashbacks
Topic Summary: acrylic/aluminium/acrylic
Created On: 12 June 2018 01:59 PM
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 12 June 2018 01:59 PM
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MPVaughan

Posts: 119
Joined: 07 August 2010

Hi all,

The latest craze in Australia is fitting 3mm acrylic splash backs which are constructed with an aluminium center but lined with acrylic on both sides.

Now, i have not really given it much thought in the past and have simply installed power points etc directly onto it however... I'm not exactly comfortable about the exposed aluminium all the way around the power point but i can actually fit an insulating shroud to get around this... In the past i haven't done this so actually considering going back to these jobs to fit them.

I just wondered how you guys deal with it as there is no such shroud available in the UK...

Cheers MPV
( ex British sparks! )
 12 June 2018 03:07 PM
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mapj1

Posts: 11252
Joined: 22 July 2004

In a brick /masonry metal wall there is a metal back box that is earthed, there is not really a credible way for the cable from back box to socket to be trapped in a way for the metal sheet to become live.
In a plaster board wall with a plastic back box it might be possible, but would still need multiple failure to make something live. I'm not sure it requires anything special, as at least with UK back boxes and sockets there is not normally a great gap. Are these sockets relying on the wall itself to provide the back to the socket?
Of course in a commercial kitchen with stainless steel sinks etc things would normally end up being earthed somewhere.

-------------------------
regards Mike
 13 June 2018 11:03 AM
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MPVaughan

Posts: 119
Joined: 07 August 2010

Thanks Mike,

I was thinking that the UK back box would be set back flush with the plaster so after the splashback gets stuck on top of that with silicone it still leaves the exposed aluminium the whole way around the socket inner and single insulation. Possibly worrying about nothing though.

The Aussies generally never use wall boxes and even when they do they are not earthed as standard. Regs here tend to rely more on double insulation and the less metal the better...

Nice to get opinions though.
 13 June 2018 11:15 AM
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AJJewsbury

Posts: 17180
Joined: 13 August 2003

My first reaction was that it's a non-problem as there should already be earthing or double/reinforced insulation between live parts and anything else (and perhaps the worry stems from the alleged AUS practice of not bothering with back boxes) - but it now occurs to me that the splashbacks might be sandwiched between the backbox (flush with the plastered wall surface) and the socket frontplate in much the manner of ceramic tiles - and being (partially) conductive - there is a risk of transferring a fault (or even inadvertant contact with terminal screws) from behind the socket to the splashback itself (or things mounted on/through it in the case of the aluminium cored acrylic ones).

In some ways it's similar to the problem with the new fashion for heavily bevelled ("metro") tiles in kitchen - if a vertical joint coincides with a socket then you've lost the IP4X protection for the upper surface. I think in that case someone suggested a thin (tile thickness) mounting frame (e.g. http://www.tlc-direct.co.uk/Products/MKK2133.html ) to fill the gap between the faceplate and socket front - a similar approach would solve the problem with conductive splashbacks - if you can find one of an appropriate depth. Perhaps something imaginative with an Yoozybox (http://www.discount-electrical...yoozybox-plasterguards ) - cutting it down to the required depth and leaving it in permanently might do the job too and might give a neater finish (but I'm not sure how that would stand w.r.t. complying with recognised standards...)

- Andy.
 13 June 2018 11:53 AM
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MPVaughan

Posts: 119
Joined: 07 August 2010

Yes exactly Andy, the splashback is actually very close to the terminals... As i mentioned in my first post, i can fit an insulating shroud to completely remove the problem but i just wanted to get some opinions as i may decide to go back to 3 or 4 previous jobs and fit them too.

You guys don't have the option of a shroud and your boxes would not protrude far enough forward to cover the aluminium.
 16 June 2018 01:21 PM
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Weirdbeard2

Posts: 523
Joined: 29 November 2017

If subject to a thorough dowsing wouldn't the socket itself be the primary risk? And bead of the silicone gun sorts out all sorts of IP issues
 16 June 2018 05:27 PM
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HarryJMacdonald

Posts: 494
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If the splash back is lined with acrylic on both sides, where is the exposed conductive part?
 16 June 2018 11:01 PM
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AJJewsbury

Posts: 17180
Joined: 13 August 2003

If the splash back is lined with acrylic on both sides, where is the exposed conductive part?

Utensil racks, microwave brackets, the stainless steel case of double insulated cooker hoods, and just about anything else that's fixed by screwing through the splashback; perhaps even the metallized trim around the edges.
- Andy.
 17 June 2018 12:52 PM
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MPVaughan

Posts: 119
Joined: 07 August 2010

Andy your'e the only person who actually understands - lets hope said splashback remains in Australia! And yes, the aluminium is definitely exposed around the edges not abutting cupboards etc

Thanks for your comments,

MPV
 17 June 2018 01:10 PM
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Weirdbeard2

Posts: 523
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hi MPV, to help the rest of us understand, what is the problem that insulating shrouds will completely remove? Are we talking cleaning water leaking into the socket going onto live terminals and also the aluminium?
 17 June 2018 02:12 PM
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MPVaughan

Posts: 119
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Hi WB2, I see no issue with water.
After the splashback installer has finished cutting out his holes my power points will fit into, the holes are always a pretty tight fit and the terminals and single insulation are very close to the inner aluminium core of the splash back when installed ( like 5mm ) and it is common to see shreds of hanging aluminium which need to be filed off around the cut out... The outer edges of the splashback can easily be touched and the core aluminium is always exposed assuming it does not abut cupboards ect

What would you do as an electrician in the UK?

1,Try and insulate the aluminium core in close proximity to the terminals ( i can do this in Aus because we have the shrouds, you dont )
2, Double insulate the wiring cores
3, Connect as usual and never give it a second thought

Cheers,
MPV
 17 June 2018 02:42 PM
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Weirdbeard2

Posts: 523
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Originally posted by: MPVaughan

Hi WB2, I see no issue with water.

After the splashback installer has finished cutting out his holes my power points will fit into, the holes are always a pretty tight fit and the terminals and single insulation are very close to the inner aluminium core of the splash back when installed ( like 5mm ) and it is common to see shreds of hanging aluminium which need to be filed off around the cut out... The outer edges of the splashback can easily be touched and the core aluminium is always exposed assuming it does not abut cupboards ect

What would you do as an electrician in the UK?

1,Try and insulate the aluminium core in close proximity to the terminals ( i can do this in Aus because we have the shrouds, you dont )

2, Double insulate the wiring cores

3, Connect as usual and never give it a second thought




Thanks for the reply, as there is no IP rating issues and assuming you file off the rough bits when fitting the socket what else is likely to cross 5mm making the bits that should be isolated live?
 17 June 2018 04:49 PM
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AJJewsbury

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what else is likely to cross 5mm making the bits that should be isolated live?

Probably about the same clearance between the terminals and the steel backbox in a normal setup (for some socket designs at least) - but you wouldn't argue that the backbox didn't need earthing (I hope). While it might be unlikely that someone would alter the position of the socket later, or a DIYer replace it with a slightly more fashionable one, and so either re-position the terminals closer to the metal or pinch the basic insulation against it, it's not really up to the standard we'd normally adopt when explicit earthing (and ADS) or double/reinforced insulation are the order of the day.

- Andy.
 17 June 2018 05:59 PM
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Weirdbeard2

Posts: 523
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Originally posted by: AJJewsbury

what else is likely to cross 5mm making the bits that should be isolated live?


Probably about the same clearance between the terminals and the steel backbox in a normal setup (for some socket designs at least) - but you wouldn't argue that the backbox didn't need earthing (I hope). While it might be unlikely that someone would alter the position of the socket later, or a DIYer replace it with a slightly more fashionable one, and so either re-position the terminals closer to the metal or pinch the basic insulation against it, it's not really up to the standard we'd normally adopt when explicit earthing (and ADS) or double/reinforced insulation are the order of the day.



Agreed, so that's why we have additional RCD protection, though I am not sure myself whether my own existing RCD protection is adequate based on the new information in the wiring matters article:

http://electrical.theiet.org/w...ctrician-should-know/

I have to charge my phone at least once every 10 days and I am worried that if my phone is on charge my RCDs won't work?
 17 June 2018 07:17 PM
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sparkingchip

Posts: 11265
Joined: 18 January 2003

There are plenty of stainless steel splash backs installed in the UK, particularly in commercial kitchens.

What's the difference?

If the splash backs are not neatly cut out and aligned they may contact the terminals of the electrical installation fittings, just like the north terminals can in some galvanised knock out boxes with four fixings.

Andy
 17 June 2018 08:51 PM
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dickllewellyn

Posts: 1434
Joined: 19 March 2010

In true "kneejerk" fashion, excuse me while I supplementary bond the foil on the back of all my plasterboard!

-------------------------
Regards
Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 17 June 2018 09:39 PM
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sparkingchip

Posts: 11265
Joined: 18 January 2003

Originally posted by: dickllewellyn

In true "kneejerk" fashion, excuse me while I supplementary bond the foil on the back of all my plasterboard!



On the other hand!
 17 June 2018 10:45 PM
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mapj1

Posts: 11252
Joined: 22 July 2004

Interesting - and that problem with the foil backed boards may be due to the absence of metal back boxes and earthed screws between fitting and the wall it attaches to that we would have here.
No one has yet suggested it, but I presume the earthing in Australia is similar in reliability to ours, despite the NE bonding permitted on the consumer side, so perhaps one could earth the offending splash back?
For comparison, the stainless steel sink in the UK normally is, either explicitly, if its an older installation, or incidentally by the piping, and in commercial kitchens stainless steel tables etc are commonly bonded if there is electrical kit in use on them. (its not regs that it must be mind you, just there is a lot of class 1 equipment in UK catering, from plate warmers and serving counters at the front to the ovens, mixers, peelers and washers out the back)
Equally, if liners for the holes for these things are made and sold, presumably for a reason, then why not fit them?

-------------------------
regards Mike
 18 June 2018 11:55 AM
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AJJewsbury

Posts: 17180
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Agreed, so that's why we have additional RCD protection

I think 415.1.2 suggests otherwise... to my mind (for ordinary LV circuits at least) we should still have either earthed metal (suitable for withstanding earth fault current) or double/reinforced insulation surrounding live parts, as part of the electrical installation.

Foil backed plasterboard usually isn't a problem in the UK - as the flush backbox (either earthed steel or insulating) should be positioned between the exposed wiring & terminals and the foil on the rear of the plasterboard.

I suspect there is a potential problem with conventional insulating surface boxes screwed into foil backed plasterboard or steel C studs - under the current regs the fixing screws are exempt from shock protection requirements. While that might have made some sense in the days when walls were pretty much insulating, it doesn't to my mind really stand up to scrutiny when the substrate can be conductive, as is the case with many modern methods of construction. The rest of the Europe (which apparently uses the same fundamental principles as us, via IEC 60364) seem to always protect their fixing screws - either with screw caps or with a box design that places the fixing screws in a separate chamber to the wiring.
- Andy.
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