LN reverse in Kitchen

Joined
14 Mar 2017
Messages
29
Reaction score
1
Country
United Kingdom
Hi I need to change a socket in my kitchen, when I bought the new socket I also bought a socket tester. In my kitchen I have 3 double sockets 3 fused sockets for the tumble dryer, washing machine and dishwasher and 1 cooker switch and socket. When I checked them the 3 double sockets and the dishwasher socket all showed the LN reverse fault. I have not checked the washing machine and tumble dryer ones yet as the machines are in the way. Also the cooker switch/socket shows that it is correct. All the rest of the sockets in the house all show correct. Has anybody got any ideas please. One other thing before the dishwasher leaked we used to get slight shocks if we touched the stainless steel interior of the dishwasher.
 
Sponsored Links
Joined
11 Jan 2013
Messages
5,289
Reaction score
1,120
Location
Durham
Country
United Kingdom
Well the first one (L/N reversed) is easy- somewhere in your house wiring someone has reversed L & N. First try the easy option- isolate the kitchen circuit, unscrew the faceplate screws of 1 double socket and have a look at the wiring. The RED (or BROWN) cores should be in the L terminal, the BLACK (and/or BLUE) cores should be in the N terminal, the EARTH wires (bare copper) should be sleeved in green or green and yellow sleeving and in the EARTH terminal on the actual socket (ideally with a link wire to the metal backbox).

If all the socket wiring is OK then the next step is to have a look in the CU (isolate before removing cover) and check the wiring there. After that you'll be looking for a junction box probably hidden somewhere.

The second one is more of a concern. Are the sockets protected by an RCD? Does your socket tester check the earth impedance (the more expensive ones will give an indication with 1 of 5 lit LEDs) or does it just light up for earth present & not for earth absent? Was the dishwasher Class 1 or Class 2?
 
Joined
18 Jul 2004
Messages
8,517
Reaction score
406
Location
Devon
Country
United Kingdom
Those socket testers can be incorrect under certain circumstances. I would suspect a high impedance or lost earth.
 
Joined
27 Jan 2008
Messages
19,720
Reaction score
1,896
Location
Llanfair Caereinion, Nr Welshpool
Country
United Kingdom
I remember a error like that, sockets bought by the box full, second fix the guy was fitting one after the other, one box the N and L were opposite to rest and it went unnoticed until the inspection and testing.
 
Joined
14 Mar 2017
Messages
29
Reaction score
1
Country
United Kingdom
thanks oldbutnotdead I will check all the sockets in the kitchen to make sure they are all wired correctly. Just a point about the dishwasher socket the socket has a metal box in the wall but no link wire to it. The consumer unit has all MCBs in it it says RCD on the outside but I cant see any in there.My socket tester is a plug in one 3 leds and a buzzer. I could not tell you if the dishwasher was class 1 or 2 it was a Beko home dishwasher. The kitchen ring is on one breaker in the CU and the cooker on a separate one. if I find one wrongly wired socket could that be the reason they all show LN reverse.
 
Joined
11 Jan 2013
Messages
5,289
Reaction score
1,120
Location
Durham
Country
United Kingdom
The link wire to the backbox is a good thing but not compulsory, as long as the earth is in the Earth terminal on the socket. If there is an RCD in the setup it'll have a TEST button on it- prod the TEST button and the thing should trip. If there are several TEST buttons then do one at a time and see what goes off

While you have the sockets off the wall (checking for correct wiring) give all the cores a good tug to make sure they're firmly in the terminals, check that the terminal screws are actually biting on bare copper not insulation, check for signs of overheating etc.

Someone suggested a poor earth may be giving you bogus readings on your socket tester. If the socket wiring all looks correct (and especially given your issue with the dishwasher) then you might want verify this by stringing a temporary earth from the main earth terminal at the meter to one of your reverse polarity sockets (bit of 1.5mm single will do)- fix the socket back on the wall before you energise the circuit, see if the socket tester shows anything different. If it does then you have a more critical issue- find the stray earth. If you're lucky it is just a loose or poorly terminated cable in one of the sockets, if you're unlucky its a bodge junction box somewhere which you need to find as a matter of urgency.
 
Joined
14 Mar 2017
Messages
29
Reaction score
1
Country
United Kingdom
Thanks for the reply oldbutnotdead definitely no test buttons in CU so no RCD then. I will check all connections on kitchen ring tomorrow. Ill let you know if I find anything.
 
Sponsored Links
Joined
2 Dec 2013
Messages
3,962
Reaction score
510
Country
United Kingdom
Plug something metal into the cooker socket.
Plug your socket tester into one of the other kitchen sockets - presumably it will light up to indictate LN reversed.
Plug something metal into another kitchen socket.
Touch the two metal things together.
Does the socket tester change?
 
Joined
8 Sep 2011
Messages
4,637
Reaction score
590
Location
Warwickshire
Country
United Kingdom
Plug something metal into the cooker socket.
Plug your socket tester into one of the other kitchen sockets - presumably it will light up to indictate LN reversed.
Plug something metal into another kitchen socket.
Touch the two metal things together.
Does the socket tester change?
I hope you mean a metal appliance and not a fork!! :LOL:
 
Joined
30 Jun 2009
Messages
21,627
Reaction score
2,567
Location
Londonderry
Country
United Kingdom
Best way to test polarity, would be to use a two pole voltage indicator at the conductor terminals or using an socket test adaptor.
If polarity is reversed it is may not be as simple as the blacks/blues being neutral or red/browns being line. Someone may have firked up upstream of the fault.
 
Joined
11 Jan 2013
Messages
5,289
Reaction score
1,120
Location
Durham
Country
United Kingdom
Best way to test polarity, would be to use a two pole voltage indicator at the conductor terminals or using an socket test adaptor.
If polarity is reversed it is may not be as simple as the blacks/blues being neutral or red/browns being line. Someone may have firked up upstream of the fault.
True enough- but our hero has limited test kit available, with luck it'll be the easy fix (someone wired the sockets wrongly) so worth checking that first. And it may be that the tester is being mislead by a flaky or absent earth
 
Joined
16 Sep 2007
Messages
1,897
Reaction score
160
Country
United Kingdom
Best way to test polarity, would be to use a two pole voltage indicator at the conductor terminals or using an socket test adaptor.
If polarity is reversed it is may not be as simple as the blacks/blues being neutral or red/browns being line. Someone may have firked up upstream of the fault.

You'll need to be quick though, the polarity changes 100 times a second.
 
Joined
14 Mar 2017
Messages
29
Reaction score
1
Country
United Kingdom
Hi I have checked all the sockets except the one behind the washing machine and all are wired up correctly. Before I started today I tested all the sockets again and all showed missing earth and not LN reversed like I said last night. I may have read it wrong last night as I thought the red led was on as well as the first green one maybe it was just a trick of the light. I don't think I can go any further.
 
Joined
11 Jan 2013
Messages
5,289
Reaction score
1,120
Location
Durham
Country
United Kingdom
Missing earth is a fairly major issue. I'm suspecting your kitchen sockets are on a radial arrangement rather than a ring final (might be wrong)- whichever, your main earth is obviously OK since the other sockets in the house check out therefore the earth is only absent between the consumer unit and the kitchen sockets. So, it'll be worth dragging the washing machine out and checking that socket (it may be the first one on the circuit), it'll be worth having a look in the consumer unit to see that the earth wire for that circuit is actually in the earth terminal in the CU, it'll be worth trying to trace the cable route from consumer unit to kitchen to see if there's a junction box hidden away somewhere.

I'd strongly advise you not to use those sockets until you have solved the problem (whether you do it yourself or get someone in)- a missing or dodgy earth on its own isn't dangerous, the danger bit is if one of your appliances develops a fault where the metal chassis becomes live. Without a functioning earth, insufficient current will flow to trip the circuit breaker. Without a functioning earth, you or your wife or children could become a path to ground when you touch the thing- again, insufficient current will flow to trip a circuit breaker but sufficient current to kill you will flow.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top