UK Gas Cooker conked and electrical cooker replacement

[advicewelcom]

Hi, quick posting - welcome any advice as new to this stuff...

Have a Howden HJA 0150 gas grill/oven with a broken thermostat that and can't get a replacement (grill igniting but no gas coming out of oven burners when on).

The Howden grill/oven is on a ring in the kitchen which has following appliances on it:
-microwave
-fridge freezer
-kettle
-toaster
-a Howden gas hob
-the busted Howden grill/oven
-couple of kitchen sockets generally not used

It all goes back to a RCD with a fuse that says - MTN132 b32 hanger fuse

There is an electrical wall connection for the grill/oven, with (I think) a 6mm wire for the ring (and not the thicker 10mm wires used for showers).


I may want to replace with just an electrical gill/oven. So some questions...

-Is there is max kilowatt oven that I could just wire into the current wall socket (which is used for the current grill/oven electrical ignition connection)?

-Would I need to replace the fuse in the RCD for the main? And is so with what?

-Would these things ensure the fuse would not trip if the oven was switched on?

-There are lots of electrical ovens but the instructions say they should be wired directly to the fuse box, so wondering if there is one which can just run from this ring main (if I upgrade the fuse)?


Would hate to buy an electrical oven and then its a nightmare and expense to fit it (the fuse box is currently full).

Welcome advice.

(attached pic of gas connection, and wall sockets for hob and grill/oven)

 

[advicewelcom]

Just to clarify - I misunderstood how the 13A socket was wired, sorry my error - you’re saying there is just a single cable going from it to the fused spur on the right?
In which case what you describe is a viable way of having it done.

Yes, think so - I assume its a ring - so the wall power wire going to the right fuse spur (for the hob) and then cable going to the twin socket.

Hopefully I can open all the sockets up - if the right fuse spur is same as left spur - can wire that up to the twin sockets - then twin sockets will be on Circuit 2.

Job's a good 'un - can have turkey for Xmas.

... but stay tuned, as betcha something will throw spanner in works.

 

[advicewelcom]

Hi, took all the sockets apart and had a good look. Its like the attached diagram, with the right hand of the twin socket wired to the hob FCU.

I assume I can just wire it up with the red line to the Boiler FCU instead and then plug the washing machine into the left hand twin socket.

This will work okay considering the above?

 

[Avo Mk8]

Hi, took all the sockets apart and had a good look. Its like the attached diagram, with the right hand of the twin socket wired to the hob FCU.

I assume I can just wire it up with the red line to the Boiler FCU instead and then plug the washing machine into the left hand twin socket.

This will work okay considering the above?

What you've drawn as the original circuit in black, would be an unusual way for the house to be wired.
Also not quite sure what the red dotted line represents, you're not thinking each socket is wired independently? (they're not!).

I would expect a kitchen ring to be wired from one accessory to the next, so from 'fuse box' to twin socket, then to gas hob fcu, then to remainder of ring, and back to the 'fuse box'. ie no link where you have the word 'circuit'.
I know your sketch is only illustrative, but you have drawn cable "T junctions" in the middle of nowhere - they must be at an accessory, so think carefully about how it forms a 'ring'
Disconnecting as you show, I believe, would break the ring (because I think the horizontal black connection doesn't exist), so the modification would reduce the current carrying capacity of the circuit, become non-compliant with the regulations, and be dangerous.
Normally taking an accessory out of a ring requires re-joining the cables as they were, with Wago's etc, to main the continuity of the ring.

As has been said before, this forum is not supposed to give step by step advice for DIY. I'm explaining the above because I don't want you to create a dangerous situation.
Working on the fixed installation of a house requires certainty and competence in what is being done.
You have described earlier in general terms how to solve the issue you had.
Just make sure it's executed correctly.

I think it's best if I don't respond further.
Keep safe.

 

[advicewelcom]

Appreciate the contact and nearly there. Issues is current COVID stuff not able to get an elecy in with older people in the house and there is an turkey that needs roasting for Crimbo, so the clock is ticking on oven installation. Thus grateful for any feedback on the below...

---

...your right, it must be a ring (can disconnect and check), but that explains that wire from twin socket to the right hob FCU.

DIAGRAM ATTACHED.

If if connect up the ring with connector block and insulation tape (behind the socket) to completed the kitchen circuit.

Then add addition 2.5 T&E (RED line) to connect the twin socket to the boiler FCU.

2.5 T&E it's good for 26Amps to support the twin sockets. Then plug washing machine into that.

The fuse in the Boiler FCU has to be 13A?

.. Is that job done?

 

[brianmoooore]

The wiring arrangement in the diagram you posted above would be compliant.
If you end up with connections from two different circuits in the same enclosure, a warning label should be fitted.

 

[advicewelcom]

Oh poo. RCD flipped off and is not switching back on. I can put things to what they were before and try it, but if RCD stays off, any ideas?

 

[DPG]

Are the 2 circuits fed from different RCDs?

 

[advicewelcom]

Pic of the one RCD with Boiler Radial and Kitchen circuit off.


RCD failed when removing the twin socket and re-connecting the kitchen circuit (pics in next posting). I don't think it would reset even when I turned the Boiler and Kitchen circuit off (but that could be me not pressing it hard enough to reset it).

 

[advicewelcom]

Before & after pics attached of wiring adjustments when RCD went off.



PIC 1. BEFORE circuit before changes
-Boiler radial circuit (pretty sure only boiler)
-Twin sockets on ring to HOB FCU and to other kitchen sockets
-Switched HOB FCU has supply, connections to HOB and back to ring (3 wires)
-Noted that the earths on Twin socket are on different ends
-Pretty sure this IS a kitchen ring as tested it


PIC 2. AFTER circuit changes
-Just connected the kitchen circuit ring up without twin sockets


Why did RCD go off?

If you connect the earths together does the RCD go pop? Just don't get it.

 

[Avo Mk8]

If you connect the earths together does the RCD go pop? Just don't get it.

I said I wouldn't
The twin socket presumably has the two earth terminals visibly strapped together?

I don't immediately see the electrical difference between the two configurations you show. I don't get it either!

You know the RCD will stay tripped if N & E somehow get connected together, even when the two MCB's you are using are off?

You might try lifting the N feed to the boiler (with it off!) just to make sure another fault hasn't appeared in the meantine, and see if you can reset the RCD.

And finally, you haven't connected the cooker in the meantime by any chance have you? If so that's another avenue!

 

[advicewelcom]

I said I wouldn't

Was your idea to plug the washing machine to the twin socket, your on the hook at the moment ;-)

The twin socket presumably has the two earth terminals visibly strapped together?

OK, well I think that means they are connected within the socket and defo not the source of the issue.

I don't immediately see the electrical difference between the two configurations you show. I don't get it either! You know the RCD will stay tripped if N & E somehow get connected together, even when the two MCB's you are using are off?

Ah Ok, could be a short between N and E then eh? I could try taking off the twin socket only (not messing with the other sockets) and trying again with the terminal block connector and see if I get the same result. I only realised the RCD tripped when someone mentioned the upstairs sockets were off - so it wasn't really event driven by me turning something on - just seemed to quietly happen by itself.

You might try lifting the N feed to the boiler (with it off!) just to make sure another fault hasn't appeared in the meantine, and see if you can reset the RCD.

I heard that lots of RCD un-correctable trips are due to boiler connections. It an old boiler so it could be something loose. You're saying to pull off the neutral on the boiler FCU connection and see if that stops tripping when using the terminal connection block to by-pass the twin sockets?

I did think I saw a 5v AC reading across the terminals of the boiler FCU even when everything was off (which was a bit weird) - pic attached.

Even if I got it working - I would have a twin socket into the boiler FCU, and would the current 3A fuse in the boiler FCU have to be replaced with a 13A fuse as it now has twin socket connected with a washing machine plugged in? Is that going to create an issue? That FCU fuse is pretty vital, it blows, no heating during winter.

And finally, you haven't connected the cooker in the meantime by any chance have you? If so that's another avenue!

The oven is always connected and has never tripped anything else, The grill on it works fine and the issue is the gas thermostat knob, but I could switch it off from its wall FCU to rule it out when testing.

 

[Avo Mk8]

Ah Ok, could be a short between N and E then eh? I could try taking off the twin socket only (not messing with the other sockets) and trying again with the terminal block connector and see if I get the same result. I only realised the RCD tripped when someone mentioned the upstairs sockets were off - so it wasn't really event driven by me turning something on - just seemed to quietly happen by itself.

If you inadvertently touched N & E together while doing the changes, that would likely have tripped the RCD. That's normal behaviour and in itself nothing to worry about. But you give the impression you couldn't then reset the RCD, which implied there might be a further problem. If you can reset the RCD, and it stays reset, all should be all OK.

You're saying to pull off the neutral on the boiler FCU connection and see if that stops tripping when using the terminal connection block to by-pass the twin sockets?"

yes

I did think I saw a 5v AC reading across the terminals of the boiler FCU even when everything was off (which was a bit weird) - pic attached.

Probably a capacitatively coupled voltage from the house wiring, and since the meter is high impedance, it gives a reading. Once you put any sort of load on, it would disappear. You see this mentioned on this forum sometimes.

Even if I got it working - I would have a twin socket into the boiler FCU, and would the current 3A fuse in the boiler FCU have to be replaced with a 13A fuse as it now has twin socket connected with a washing machine plugged in? Is that going to create an issue? That FCU fuse is pretty vital, it blows, no heating during winter.

You're confusing yourself! You have a 20A radial from the 'fuse board' which you should connect directly to both the twin socket and the input to the fcu. Do not connect the twin socket to the boiler side of the fcu!

You don't need to change the fuse, leave as is.

The oven is always connected and has never tripped anything else, The grill on it works fine and the issue is the gas thermostat knob, but I could switch it off from its wall FCU to rule it out when testing.

Sorry I was meaning if you had bought a new electric oven and connected it. They occasionally cause this sort of problem. Ignore this.

Hope you sort it.

 

[marconi]

Good morning. MAy I ask some questions please?

1. Does the rcd trip when the washing machine is unplugged?

2. How, step by step, do you re-apply power? eg: all mcbs and RCD are on and i use the red main switch. Or. the main switch is on as are all the mcbs and I use the RCD. Or, the two mcbs in question are off and the RCD is off, the main switch is on and I then I turn on the RCD. Or, MAin switch is on, RCD and two mcbs are both off, and then I turn on the RCD and then the 20A mcb and then the 32A mcb?

3. Turn off red main switch and then CArefully remove lid of the consumer unit and take a photo of the wiring top and bottom of the RCD and then put the lid back on. DO NOT PUT YOUR FINGERS INSIDE!!!

4. With your multimeter set to the highest ac voltage range measure the voltages between:

a. earth of left hand FCU and the earth of the double socket to its right.

b. earth of the double socket and the securing screw of the FCU which switches the socket below for WM.

5. With Main Sswitch Off and your MM set to low ohms setting measure the resistance between:

b. earth of LH FCU and boiler pipes.

c. boiler pipes and a securing screw of the FCU which switches the socket for washing machine.

d. the securing screw of the FCU and a securing screw of the socket for the washing machine.

e. Between the pins of the plug of the washing machine L-N, L-E and N-E.

 

[advicewelcom]

Good morning. MAy I ask some questions please?

1. Does the rcd trip when the washing machine is unplugged?

Hi, yes, the washing machine was off and out of the twin socket when changing the wiring. I suspect this is me being careless with the N and E as mentioned before, but I have to go in with a testing approach (hopefully today) to try again.

2. How, step by step, do you re-apply power? eg: all mcbs and RCD are on and i use the red main switch. Or. the main switch is on as are all the mcbs and I use the RCD. Or, the two mcbs in question are off and the RCD is off, the main switch is on and I then I turn on the RCD. Or, MAin switch is on, RCD and two mcbs are both off, and then I turn on the RCD and then the 20A mcb and then the 32A mcb?

Will be mindful of this on the 2nd testing, but the last time

• Main switch was on
• RCD was on
• Two circuits for boiler and kitchen ring were off

Did was wiring changes, then was told sockets were not working upstairs - went to check and found the RCD tripped and unable to reset until I changed the wiring back to what it was before.

3. Turn off red main switch and then CArefully remove lid of the consumer unit and take a photo of the wiring top and bottom of the RCD and then put the lid back on. DO NOT PUT YOUR FINGERS INSIDE!!!

Okay - should be able to do that, bit tricky to get the cover off, but can do it carefully, understand there is live connections via the tails (I think) so not touch anything inside.

With the below I assume u mean the securing screw of the wire inside and not the silver securing screws of the socket visible outside.

4. With your multimeter set to the highest ac voltage range measure the voltages between:

a. earth of left hand FCU and the earth of the double socket to its right.

OK - V's between Boiler FCU Earth to double socket Earth

b. earth of the double socket and the securing screw of the FCU which switches the socket below for WM.

*There isn't a FCU for the WM twin socket? - I think you mean Volts across Twin socket Earth to HOB FCU Earth (pic attached)

5. With Main Sswitch Off and your MM set to low ohms setting measure the resistance between:

b. earth of LH FCU and boiler pipes.

Ok - Ω's between Boiler FCU Earth to Boiler pipes

c. boiler pipes and a securing screw of the FCU which switches the socket for washing machine.

OK - Ω's between Boiler pipes and Twin socket Earth (I assume)

d. the securing screw of the FCU and a securing screw of the socket for the washing machine.

OK - Ω's between HOB FCU Earth and Twin Socket Earth

e. Between the pins of the plug of the washing machine L-N, L-E and N-E.

OK - Ω's between washing machine plug pins L-N, L-E, N-E


*Welcome to clarify the above.

Can add this approach to the general test strategy if I have the same problems when trying again with the wiring.

 

[advicewelcom]

You're confusing yourself! You have a 20A radial from the 'fuse board' which you should connect directly to both the twin socket and the input to the fcu. Do not connect the twin socket to the boiler side of the fcu!

Just have to clarify this (PANIC STATIONS).

You are saying to connect from the Boiler FCU supply input to the TWIN SOCKET?

Think you're saying don't connect from the FCU output going to the boiler.

Attached a diagram of potential new wiring - is this correct? - wire from the Twin socket into the Boiler FCU Live, Neutral & Earth Supply connections??

And terminal block connect the incoming 32A ring supply to the HOB FCU??