kitchen electrics and safe zones

[jamesmjf]

Quick question. Imagine a kitchen worktop with a ring main above the worktop with double sockets. A DP switch is on that ring main switching a spured socket below the worktop for a socket for a washing machine. I know that cable runs have to be vertical or horizontal if between accessories but if the DP switch can't be directly vertical above the socket (if there is a sink above for example), how can this be achieved if you can't drop below the worktop and then do a 90deg to behind the washing machine.

Probably clear as mud!!

Regards

James

 

[rjm2k]

Just waiting for the Part P responses to come along.., in the meantime I believe that you can cable outside of safe zones if the cable is more than 5cm deep in the wall or run through suitable metal conduit and RCD protected.

But I'm no expert, I'm sure your part p electrician will be able to tell you.

 

[bernardgreen]

In theory the DP switch creates a "safe zone" vertically above and below it and the socket creates a "safe zone" horizontally either side of it so the bend wil be at the intersection of two "safe zones".

Unfortunately many people ( other than good electricians ) do not know about (un) "safe zones" so the cables are not really safe even when in a "safe zone".

I would put a back box and blank front plate where the cable changes direction as a marker.

I would not put the socket directly behind the machine but to one side where it can be accessed for checking, replacing the fuse without having to move the machine.

 

[rjm2k]

I would put a back box and blank front plate where the cable changes direction as a marker.

Trouble is, in a kitchen the marker is likely to be hidden behind a unit (as I found the other day when removing a unit).

 

[ban-all-sheds]

I suggest you use steel conduit - start looking on eBay for a second hand bender.

 

[xdave]

As Bernhard said the socket will create its own horizontal zone which you follow until it enters the vertical zone for the DP switch.

It's not just that many people won't realise those are safe zones but also that many people don't realise there are any safe zones despite almost every cooker in the country being wired in that way. I've jumped in before when people have started drilling or marking up holes without paying any attention to nearby electrical accessories. I helped replace all of the cable drops in a friend's kitchen when they drilled through every single one of the cables supplying their sockets when putting up the wall cabinets. Every single one *. Their excuse was "I thought they would run between the sockets", and when I asked how the cables got to the first and last sockets they said they come up from the floor. (This was in a bungalow with concrete floors.) You cannot assume common sense will always prevail.

In a kitchen, given the density of the sockets and other accessories, and how people like to drill lots of holes to hang things on, I would always run the cables in steel conduit between the ceiling and worktop height. Any cables under the worktop could either be installed in conduit or chased bare into the walls but I would fill the chases with a dissimilar material so it was plainly obvious that they contained the cables. If a run will not be visible then there is no reason to hide it.

* Where cables are run down from the ceiling it is good practise to stick the first and last socket and to bring down all the cables between 150 and 250mm of a corner as it is unlikely that that space will be drilled into to hang wall units or shelving, etc. Although you should use hanging rails for wall units in the corners of rooms to avoid drilling the safe zone most fitters and DIYers don't bother as it is an extra expense.

 

[caffreys]

Could you just use armored cable in this instance (does that offer mechanical protection outside of safe zones?) I've a similar situation for cooker hood and routing - would save cable going up and down the walls.
Cable from floor to isolator, back down to floor, then back up to fcu or unswitched socket.

End of the day, drills seem to have some magical power for finding cables ;p good job modern DBs have rcbo protection.

 

[ban-all-sheds]

I helped replace all of the cable drops in a friend's kitchen when they drilled through every single one of the cables supplying their sockets when putting up the wall cabinets. Every single one *.

It's OK - you aren't talking to LABC now....

 

[Click4]

Unless you work for LABC BAS lol

 

[xdave]

As it happens I do some work for a LA, but in this instance he really did drill through every cable drop and hit at least one of each pair. From memory there were four drops, and they were all perfectly central in their respective safe zones. When he phoned me he explained that when he tried to turn the kitchen breaker back on the whole fuse box would trip and it had been like it for a week but needed sorting soon as the kitchen was almost finished. Expecting that he had trapped a cable when refitting a socket after tiling I happily agreed to take a look. When walking into the kitchen the first thing I noticed was that a lot of the sockets were directly in line with the edges of wall units. After faffing around wondering why the continuity was all over the place (I was only expecting one fault) I removed the cornices and lifted one of the units off to find perfect continuity between the mounting bracket and the earth of the socket below. The others were easier to find - I just removed the sockets and lined up the conduit with the brackets.

I felt so sorry for the original electrician - they must have thought "there is no way anyone would be stupid enough to hit these cables". Well it turns out that human stupidity knows no limits. Fortunately for my friend the electrician had used conduit so I was able to remove the old cables and rod in the replacements without ripping the kitchen out but my friend was still not very pleased and the whole thing took a day to sort out. The really frustrating part was that he could have used any of the other holes in the bracket to mount them. Another good reason to use rails rather than brackets.

 

[ban-all-sheds]

Plus they make life so much easier. POP to get a rail level.

 

[phatboy]

When I re-did my kitchen, I buried the cable vertically below the DP switch, then brought it back to the surface just below worktop height. Put a 90degree bend in the cable inline with the under-counter socket, and ran it to the socket. Clipped it to the wall all the way, as it was going to be hidden by the units anyway