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QUICKY question to resolve a dispute, haha! (a clue would be... a DSO / other near a sink)...
Tomgunn
122 Posts
Question
Hiya, I know everyone's busy so this is a QUICKY!!

How far, (if any), does a DSO / SSO / Sw'd Spur etc... have to be away from a kitchen sink?

Fanks...¬†ūüėé

regards... 

 
26 Replies
Normcall
42 Posts
Think to yourself, is it a room with a fixed bath or shower.
However putting our the socket between the tap(s) is not really a good idea.
AJJewsbury
1881 Posts
From memory 300mm horizontally is in some guidance. Nothing that specific in the regs themselves though - just has to be suitable for the environment.
   - Andy,
mapj1
2467 Posts
No actual distance is given inthe regs, but the "must be suitable for the environment" bit still applies, so it rather depends how far you expect things to get splashed. At one time NICIEC advised at least 30cm horizontal , but that was never regs.  (edit  they still do ) Clearly in reality the taps are rather more of a risk then the shallow end of a draining board,and maybe less than 30cm horizontal is OK if there is a large vertical offset instead. Any sink with a pullout hose in a family home with kids, and I'd be adding quite a bit more margin.
Tomgunn
122 Posts
I / we'd never do this anyways... just wondered what was the regs, for this as I remember, a few years ago, a BBC investigation programme, (Dom Littelwood), had an 'electrician' inspect a cowboy job and asked about the DSO, near a kitchen sink, and the chap said it has to be "30cm" and then a post on this forum... all laughed at that 'electrician' as there is no guidance for the DSO... wondered if things had changed?

regards to all!
Tomgunn
122 Posts
Normcall:
Think to yourself, is it a room with a fixed bath or shower.
However putting our the socket between the tap(s) is not really a good idea.

Hello Norman...

Agreed! 

regards... 

Tomgunn
122 Posts
mapj1:
No actual distance is given inthe regs, but the "must be suitable for the environment" bit still applies, so it rather depends how far you expect things to get splashed. At one time NICIEC advised at least 30cm horizontal , but that was never regs.  (edit  they still do ) Clearly in reality the taps are rather more of a risk then the shallow end of a draining board,and maybe less than 30cm horizontal is OK if there is a large vertical offset instead. Any sink with a pullout hose in a family home with kids, and I'd be adding quite a bit more margin.

Thanks... BUT 'guidance!'

Of course no sparky worth his salt would do this.

regards...

Chris Pearson
1763 Posts
"Far enough" is my answer.
I am not a follower of the "I need a rule (guide, advice, magic wand etc)", in this kind of case. These "rules of thumb" are all very well, but as all appliances have a cable longer than 300mm, just what is this number supposed to represent? If it is a kettle, then earth cable failure and then a fault to case is equally dangerous if the socket is 2m away, given accidental contact. Splashing with water is not really very dangerous, you may get corrosion inside the socket pins but not much else. The safest thing in a kitchen is to use plastic plumbing, to ensure the sink is not bonded to Earth, hide all the appliances behind wood doors, and having a non-conductive floor covering. Under these conditions, it is very difficult to get a shock whatever happens, and if everything is RCD protected is unlikely to cause injury even if a shock could be obtained.
OlympusMons
150 Posts
NHBC agree with the 300mm guidance https://www.procertssoftware.com/wp-content/uploads/2020/06/NHBC-Electrical-Fittings-Near-Cookers-Sinks-and-Wash-Basins.pdf
They measure from the basin, so their diagram has a DSO above the draining board.
They recommend 100mm from a hob, but most manufacturers of gas hobs recommend 50mm from the edge of a hob to a combustible surface, which does seem a bit close to me.
Ed57
1 Posts
Minimum 300mm horizontal distance from the nearest edge of the socket to the nearest edge of the sink
 
UKPN
169 Posts
"ensure the sink is not bonded to earth" 
Too right, thats so "yesterday"! What are those little tags with a 2BA hole in the middle anyway? 

Regards, UKPN⚡
Chris Pearson
1763 Posts
UKPN:
"ensure the sink is not bonded to earth" 
Too right, thats so "yesterday"! What are those little tags with a 2BA hole in the middle anyway? 

Regards, UKPN⚡

If you see a hole, put something in it!¬†ūüėĀ

ebee
830 Posts
"have to be away from a kitchen sink "

Depends on all circumstances in the situation installed Tomm, not a fixed dimension in the regs (all of guidances are worth considering.)
You are a bit behind the times UKPN, the "bond everything" 15th edition was found to increase danger (particularly in commercial kitchens), as they became conductive environments. Why would you want to bond an otherwise unconnected conductive part anyway, why not bond the saucepans?
OMS
719 Posts
Although it has to be said, that if you have say a commercial kitchen, and you re establish a zone of protection by bonding extraneous conductive parts back to the earth terminal on the kitchen DB (which is local to the kitchen) you will substantially reduce touch voltages  - the basis physics says so.

That doesn't mean bonding the legs of moveable tables and the like, I agree - but as a principle re establishing that zone of protection is no bad thing

Regards

OMS
perspicacious
370 Posts
Too right, thats so "yesterday"! What are those little tags with a 2BA hole in the middle anyway? 


Years ago, I understood the BS that sinks were made to, required the provision of said tag................... I haven't checked what BS number it is nor if it is still a requirement,

Regards

BOD
Chris Pearson
1763 Posts
perspicacious:
Too right, thats so "yesterday"! What are those little tags with a 2BA hole in the middle anyway? 

Years ago, I understood the BS that sinks were made to, required the provision of said tag................... I haven't checked what BS number it is nor if it is still a requirement,

BOD is spot on!

BS 1244-2:1988
12 Earth terminal
Sinks shall be provided with an effective means of attaching a bonding conductor which shall be accessible to the electrician after the sink has been installed. This conductor shall be either a tag with a bolt size designation of M6, in accordance with BS 4190, (8.3 mm minimum) clearance hole or an M6 bolt or threaded stud. The tag, bolt or stud shall be protected during any enamelling process to ensure that a good electrical contact can be made.


The requirement (in less detail) goes back at least as far as 1956, but disappeared when the BS was superseded in 2003 by BS EN 13310.

geoffsd
170 Posts
 the "bond everything" 15th edition 


The 15th did not require nor state anything fundamentally different than the 18th.

The bond everything was a misinterpretation of what it actually said.

Similar to people reading the list in 411.3.1.2 without correctly reading the sentence above which states "extraneous-c-ps including the following".

 

Tomgunn
122 Posts
davezawadi (David Stone):
I am not a follower of the "I need a rule (guide, advice, magic wand etc)", in this kind of case. These "rules of thumb" are all very well, but as all appliances have a cable longer than 300mm, just what is this number supposed to represent? If it is a kettle, then earth cable failure and then a fault to case is equally dangerous if the socket is 2m away, given accidental contact. Splashing with water is not really very dangerous, you may get corrosion inside the socket pins but not much else. The safest thing in a kitchen is to use plastic plumbing, to ensure the sink is not bonded to Earth, hide all the appliances behind wood doors, and having a non-conductive floor covering. Under these conditions, it is very difficult to get a shock whatever happens, and if everything is RCD protected is unlikely to cause injury even if a shock could be obtained.

Food for thought! BUT, here I go... getting into trouble, AGAIN!

BUT, I know we've all heard about 'introducing a potential where a potential may not exist' BUT... if the property has copper  plumbing to the sink then why do we not have any earth bonding there, nowadays? What happened, (like yeah man... I know about 'parallel earthing'), to 'cross bonding' as I did this for decades, hahaha... am I gonna get shot down!!!?? 

Don't be too hard on me, I'm old!!!¬†ūüėé

regards...

Tomgunn
122 Posts
OlympusMons:
NHBC agree with the 300mm guidance https://www.procertssoftware.com/wp-content/uploads/2020/06/NHBC-Electrical-Fittings-Near-Cookers-Sinks-and-Wash-Basins.pdf
They measure from the basin, so their diagram has a DSO above the draining board.
They recommend 100mm from a hob, but most manufacturers of gas hobs recommend 50mm from the edge of a hob to a combustible surface, which does seem a bit close to me.

It's like wall units too... they have to be a certain distance away from a hob and that goes for sockets too re; the heat.

regards...

Tomgunn
122 Posts
ebee:
"have to be away from a kitchen sink "

Depends on all circumstances in the situation installed Tomm, not a fixed dimension in the regs (all of guidances are worth considering.)

Thanks again for good advice as with all of the other replies too.

Thanks everyone!!

regards...

Tomgunn
122 Posts
davezawadi (David Stone):
You are a bit behind the times UKPN, the "bond everything" 15th edition was found to increase danger (particularly in commercial kitchens), as they became conductive environments. Why would you want to bond an otherwise unconnected conductive part anyway, why not bond the saucepans?

Hiya, that's fair enough but, as you state more to do with 'commercial' kitchens BUT... why not earth EVERYTHING, (including the steel pans, haha)???

WHAT, if there was a damaged cable that was touching some pipework that wasn't bonded???

BRING BACK RYB, hahaha!!

cheers...

Tomgunn
122 Posts
OMS:
Although it has to be said, that if you have say a commercial kitchen, and you re establish a zone of protection by bonding extraneous conductive parts back to the earth terminal on the kitchen DB (which is local to the kitchen) you will substantially reduce touch voltages  - the basis physics says so.

That doesn't mean bonding the legs of moveable tables and the like, I agree - but as a principle re establishing that zone of protection is no bad thing

Regards

OMS

See my other questions, further down...

regards...

AJJewsbury
1881 Posts
WHAT, if there was a damaged cable that was touching some pipework that wasn't bonded???
Just the same as if a person was touching a damaged cable. I hope no-one's suggesting we start bonding them!  I think the emphasis these days is on keeping the cables in good condition and not running them next to pipework in the first place, let alone squeezed through the same hole in a joist and so on. The responsibility for dealing with electrical faults should be within the electrical system - rather than trying to chase them all around the house via and old bit of metalwork that other trades might or might not have supplied and may or may not alter (e.g. with plastic joints) when our backs are turned.

Plus of course earthing/bonding everything in sight can often increase shock risk - by creating a path to earth for the victim where might not have been one before.

   - Andy.
mapj1
2467 Posts
There are however some domestic installations where bonding the person to ground makes sense, but I'd suggest these occur quite rarely.

A touch over a megavolt here at ~100KHz, but average current of less than milli-amps path completes by body capacitance to ground and from ground to underside of HV coil.
I wonder if it would trip an AFDD ?

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