Strange wiring discovered - help

[MarsExpress]

Hello...

I am trying to install a new built-in electric cooker to REPLACE an old built-in gas cooker.

The gas cooker has been removed, and the gas supply capped, by John Lewis, but they could not install the new electric cooker, and left me in the lurch.

I have located the mains supply (down the back of the built-in kitchen units, removed the kick-board from the bottom of the units, and dragged the mains cable out from underneath).

It is a spur with a junction box connecting two appliances. One is connected to the automatic ignition of the gas hob (which I am retaining), and the other connection was to the gas cooker (it had an internal light, fan, clock, timer and automatic ignition, which I am not retaining).

My intention was to remove the cable to the gas cooker, retain the cable to the gas hob, and connect a new 2.5mm cable to the new electric cooker. Simple?

Removing the top from the junction box revealed weird wiring:

Mains red was connected to both appliances red - correct.
Mains black was connected to both appliances earth - wrong(?)
Mains earth was connected to both appliances blue - wrong(?)

That is NOT right, is it? Was it dangerous?

I can test that the red is, indeed, LIVE.

But how can I test which is the real return circuit (which should be black or blue coding)?

At the moment I cannot get to the other end of the mains spur to see how that end is connected to the ring main. I need to knock the back out of a kitchen unit, and I don't want to do that unless necessary.

All that I have working (now that the gas cooker has been removed) is the ignition to the gas hob. That works whether it is wired:

Mains red -> appliance red
Mains black -> appliance earth
Mains earth -> appliance blue

OR

Mains red -> appliance red
Mains black -> appliance blue
Mains earth -> appliance earth

But it takes next to no current.

I cannot understand how my old gas cooker worked, driving a fan etc, with the RETURN and EARTH mixed up?

Did my kitchen installers - 20 years ago, balls up the connections when they connected the mains spur to the ring main? Have I been running a return circuit, through this spur, on an unsheathed "earth" wire?

Am I right in being very reluctant to continue their "crazy" wiring on this spur considering I now want to power an electric oven, and not just a fan and other low-power stuff?

I don't know, off hand, how to test which of the BLACK or unsheathed earth is really taking the return current? Might there be an easy test?

How would an electrician test this "crazy" setup?

(I must say, I have checked other, accessible, circuits my kitchen installers put in and they are all normal)

This has properly flummoxed me!

 

[stem]

Depending upon the size of the new cooker, (unless by "cooker" you actually mean an oven without a hob which you may do as you are retaining the gas hob) you will probably need a much larger electrical supply than required by the previous gas cookers ancillaries. This will likely mean a new dedicated circuit and a much larger cable. Probably why John Lewis refused to connect it.

Please refer to the instructions that came with your "electric cooker" you should find this information there.

Regarding the junction box. If I understand what you are saying correctly, the wires are not in the terminals as labelled. However, as long as the lives, earths and neutrals are connected together correctly, whilst not good practice, it's not really dangerous, unless the earth terminal is mechanically attached to a metal part of the junction box that needs an earth connection.

You could either trace the cables to see what they are connected to at the other end, or obtain professional test equipment to check the wiring properly along with someone capable of using it.

 

[PrenticeBoyofDerry]

Firstly it is important to know the output of the new appliance, as this is important and will dictate the design of the circuit, such as fuse rating and cable sizing.

With regards to existing termination, reverse connection of earth and neutral is wrong but will allow the appliance to work. To determine identity, continuity and correct termination of the conductors, you will require to do some continuity test using a low ohms reading meter/continuity tester.
You will require to link live to earth and then test for continuity, this would normally confirm r1+r2 and polarity. You could also use either the live or earth linked to neutral to ID this back at the board.

 

[MarsExpress]

Depending upon the size of the new cooker, (unless by "cooker" you actually mean an oven without a hob which you may do as you are retaining the gas hob) you will probably need a much larger electrical supply than required by the previous gas cookers ancillaries.


"Yes, I realised that. That is why I went and purchased 2.5 square mill cable, so I could connect the cooker (I do mean an oven without a hob - I didn't know there was a definition."


This will likely mean a new dedicated circuit and a much larger cable.

"Yes. I mislead you - sorry. Thinking about my posting later I realised I said it was on a spur to the ring main, but it is not. It is on a dedicated "cooker circuit", so what I can see dangling underneath my kitchen units is an extension of that circuit, with a wall switch above. (I know it is on a dedicated circuit because it has its own dedicated fuse within the mains fuse box, and isolating that knocks it out, but nothing else whatsoever)."


Probably why John Lewis refused to connect it.


"No. They refused because they didn't want to scrabble around hooking the cable out from underneath the kitchen units. They didn't want to replace "a double oven with a single oven" - it wasn't a double oven, it was an oven with a separate grill. I pulled the fuse and showed them how to upgrade it to 15A. They didn't want to replace gas with electric because "that was a 90 minute job and they had only been given 25 minutes". They then said the gas cooker could not be removed until I showed them, myself, how to do it. And when they discovered its junction box was down the back of the kitchen units, they said it was "impossible to reach and refused to do any more work"...

I was left to do it myself by removing the kickboard and hooking it out. I had to cut the appliance cable to the gas cooker, in order to release it, myself because they said they could not take the risk, even though I was holding the mains fuse and the circuit was dead. I had paid £95 for installation"


Please refer to the instructions that came with your "electric cooker" you should find this information there.


"I studied the instructions very carefully. There is NO installation instructions whatsoever other than: 'This appliance is supplied without a main plug and a main cable. Use 2.5 square mil PVC twin and earth'.

Took me ages to work out how to get the plastic cover off the terminal block on the back of the oven!"


Regarding the junction box. If I understand what you are saying correctly, the wires are not in the terminals as labelled. However, as long as the lives, earths and neutrals are connected together correctly, whilst not good practice, it's not really dangerous, unless the earth terminal is mechanically attached to a metal part of the junction box that needs an earth connection.


"Sorry, you did not understand me correctly: BLACK is connected to green/yellow earth, and UNSHEATHED EARTH is connected to blue, on *both* appliances within the junction box. The terminals, themselves, are not labelled - are they ever?"


You could either trace the cables to see what they are connected to at the other end, or obtain professional test equipment to check the wiring properly along with someone capable of using it.

"Sorry, can't trace back because it goes into the wall behind a kitchen unit. I need to break out the back of the kitchen unit, which I would like to avoid."

That is my reply, above. Cheers.

 

[MarsExpress]

Firstly it is important to know the output of the new appliance, as this is important and will dictate the design of the circuit, such as fuse rating and cable sizing.


"Thanks. I changed the "cooker circuit" fuse to 15A and bought 2.5 square mill cable. The cooker has no rating either within its manual, or on any rating plate - other than 230v - 250v 50 htz.


See my posting reply to "stem" about other 'problems' I had with John Lewis and the fact that I did mislead you by saying it was on a spur: it is not, it is on a dedicated "cooker" circuit.

Searching the John Lewis web site they say 16A. I figured I would try 15A first, and see how that goes."


With regards to existing termination, reverse connection of earth and neutral is wrong but will allow the appliance to work.


"OK. Thanks. That would explain how both my hob and gas oven worked, then. I did correct the connection for the hob, and tested that it still worked. I was just worried that the new oven will pull a much bigger current."


To determine identity, continuity and correct termination of the conductors, you will require to do some continuity test using a low ohms reading meter/continuity tester.
You will require to link live to earth and then test for continuity, this would normally confirm r1+r2 and polarity. You could also use either the live or earth linked to neutral to ID this back at the board.

"Thanks again. I don't have the equipment. I wonder if I should try and buy one - or test with some sacrificial piece of equipment, connect it up correctly, stick the fuse in, switch it on at the wall and stand back..."

Sorry about the clungey reply, above. I cannot get HTML switched ON with this system, and none of the bold, italics, font colour tags seem to work for me.

 

[RF Lighting]

Can you provide a link to the cooker on the website for example?

There will be a rating plate somewhere on the oven. Often it's inside the oven near the edge when the doors open.

 

[MarsExpress]

Can you provide a link to the cooker on the website for example?

"Hello..

it is http://tinyurl.com/ktzkzdg "


There will be a rating plate somewhere on the oven. Often it's inside the oven near the edge when the doors open.


"Thanks. I had looked inside, but since the oven is still on the floor I cannot properly open the door I have just had a second try and it does give a kW rating, but in such very tiny print I missed it first first time. I think is says kW = 3.1 - 3.3.

(I am a widower pensioner. There were two reasons I needed John Lewis to install the damn thing: disconnecting the old gas cooker and not possibly being able to lift the new one into place on my own. But they have left me in the lurch. So, sitting on the floor I can only prize open the door a fraction:-}

Cheers."

 

[skotl]

Have you tried calling John Lewis? It doesn't sound like them to leave someone like you in the lurch.

Plus, I suspect that the answer to your questions on here will end up being "you need to get an electrician".

 

[deadshort]

I have had to connect ay least 4 cookers that JL refused to connect and the customer has been left without a cooker.

ALL got a full refund on the installation charge.

Regards,

DS

 

[MarsExpress]

Have you tried calling John Lewis? It doesn't sound like them to leave someone like you in the lurch.

"Hi..

I had been emailing them ever since I phoned Customer Service last Wednesday enquiring whether they realised they were replacing gas with electric. That was when the problems started... They told me they could not do that because "it was against Health and Safety"...

Nowhere on their online form did they ask the fuel types of the appliances to be swapped. They just said "£95 for both fuels', and that was it.

I was stunned. I tried to get clarification but promised returned phone calls never materialised, and they did not respond to my emails, either.

As far as I was concerned, when the new cooker turned up this morning I was expecting them to say we cannot deal with gas, but that never happened. They said they deal with gas and electric "all the time", but because they had not been told, they had only 25 minutes allocated for the job. And then it just went down hill from there...

It has been a balls-up from beginning to end. And it wasn't the gas which fazed them, it was the thought of dealing with my electric circuit behind and underneath all the kitchen units.

And when I tried to finish what they had refused to do, *I* discovered this weird wiring anomaly my old kitchen installers had used...

Meanwhile, strangely enough, my emails had been 'escalated' to some Head of Customer Service, and he has just phoned me. We had a long chat. He was 'disappointed' the installers had abandoned me, and I told him that his online form did not ask enough questions of the customer, how many stairs, access, fuel types(!) involved, and whether it was built-in or not (stand alone being so much easier). That should then give their installers a better idea of what to expect, and to allocate them more time. They also need to be more resourceful when faced with problems: not all kitchens are perfect.

I am going to soldier on, and Mr Head of Customer Service is going keep in touch, and if I do need third-party help, John Lewis will pay. Apparently. But that takes time: I reckon I can do everything but lift the oven (I don't think the wiring anomally is systematic: I suspect that my old kitchen installer knew the appliances would still work (something I did not know, myself) with 'neutral wired to earth, and vice versa' and just did what came easiest?

If I get stuck, I will call upon Mr Head of Customer Service.

Meanwhile, he needs to get their online forms sorted out to ask more relevant questions, and maybe to get John Lewis contracted installers to be more prepared to deal with award electrics?"





Plus, I suspect that the answer to your questions on here will end up being "you need to get an electrician".


"I'm hoping not, but I may have to change my mind...

Cheers."

 

[PrenticeBoyofDerry]

Well it seems the appliance requires 16A supply, according to the spec on the link, so 2.5mm2 cable will be okay to supply the oven. A 16A device at the consumer unit should be adequate to supply both hob and oven from a dual outlet at the appliances.

 

[MarsExpress]

Well it seems the appliance requires 16A supply, according to the spec on the link, so 2.5mm2 cable will be okay to supply the oven. A 16A device at the consumer unit should be adequate to supply both hob and oven from a dual outlet at the appliances.

"Thanks.

I still have an old style fuse wire consumer unit:-} I stuck a 15A wire in, and will see how that copes. I can up it to 20A.

I always meant to get a modern consumer unit, but life kept getting in the way

Cheers"

 

[ban-all-sheds]

Sorry about the clungey reply, above. I cannot get HTML switched ON with this system, and none of the bold, italics, font colour tags seem to work for me.

Are you using Firefox? //www.diynot.com/forums/forum-information/bbcode-buttons-and-firefox.380296/

But bold, colours, size changes etc - all useful to have.

[quote] [/quote], OTOH, are virtually essential - you may just have to type them by hand. Your posts are very hard to follow without.

 

[MarsExpress]

Sorry about the clungey reply, above. I cannot get HTML switched ON with this system, and none of the bold, italics, font colour tags seem to work for me.

Are you using Firefox? //www.diynot.com/forums/forum-information/bbcode-buttons-and-firefox.380296/

But bold, colours, size changes etc - all useful to have.

[quote] [/quote], OTOH, are virtually essential - you may just have to type them by hand. Your posts are very hard to follow without.

Not using Firefox - using Safari. I tried unsuccessfully to select text and then click on B(old), i(talic) u(nderline) etc but nothing changed in Preview? I then tried selecting text and "Font colour", but nothing changed.

It is offering options which do not appear to be working.

I wanted to interleave my replies to the text to which I was replying, and to make it easy to read, but had to resort to using quotation marks, which was far from optimal...

I noticed under Options it indicates that HTML is OFF, and there is no way to switch it on I can disable BBCode, whatever that is, and Smilies, but that is unlikely to help...

I note the comment about using [quote] and [/quote]

Cheers

 

[JohnW2]

I noticed under Options it indicates that HTML is OFF, and there is no way to switch it on I can disable BBCode, whatever that is, and Smilies, but that is unlikely to help... I note the comment about using [quote] and [/quote]Cheers

"BBCode is what you want to be using (as you've discovered, HTML is not available).

It sounds as if, with your browser, you are stuck with typing in BBCcodes manually. You don't have to restrict yourself to just [*quote]...[*/quote] (remove those asterisks when you use them) - you can also use [*u]xxx[*/u] for underline, [*b]xxx[*/b] for bold and [*i]xxx[*/i] for italic etc.(remove the asterisks when you use them) ... even if it is a bit of a pain. Alternatively, use a different browser (not Chrome - that doesn't work, either!)

Kind Regards, John