Author Topic: Replacing an electric hob  (Read 758 times)

fuaran

  • rothair gasta
Replacing an electric hob
« on: August 27, 2019, 06:33:16 pm »
How hard is it to replace an electric hob?
Induction hob has stopped working, so need to replace it. It is wired in, on a 30A circuit.
How to disconnect and remove the old one, and fit the new one? What sort of connectors and tools do you need.

Shops say it should be done by a qualified person, but can you DIY?

And any recommendations for a decent induction hob? Preferably with proper knobs/buttons, not annoying touch controls. Seems most of them now are just touch controls.

Feanor

  • It's mostly downhill from here.
Re: Replacing an electric hob
« Reply #1 on: August 27, 2019, 06:40:11 pm »
Replacing like-for-like ought to be fairly trivial.
I'd not expect to need much more that a screwdriver for the electrical work.

Follow the cable from the existing hob back to where it terminates at the wall.
Open up the faceplate.
Inspect.

Disconnect and re-connect new unit as required.

It might be that the 'tail' is not part of the new hob, and you may need to either re-use the existing bit of cable, or get a new bit of cable. It's a case of inspect and then decide.


Kim

  • Timelord
Re: Replacing an electric hob
« Reply #2 on: August 27, 2019, 06:43:38 pm »
Probably just a bastard thick cable into screw terminals on the hob.  Required tools are likely to be an assortment of screwdrivers, but probably wise to have wire cutters/strippers on hand too.  Part P shouldn't be an issue due to like-for-like appliance replacement.

If the cable needs replacing due to  being too short, then you'll probably have to go back to the Big Red Isolator Switch™ (I wouldn't introduce an extra junction on a high-current circuit unless I *really* had to).  Again, screw terminals, and anything you need to do sort out the physical arrangement of the cable (plastering, conduit, etc).  Obviously it needs to be the same thickness of cable.

Note the importance of screw terminals being done up bastard tight: If they're loose, the junction's excessive resistance leads to heating, which loosens the screw, which increases the junction's resistance, and eventually either there's a funny fishy smell and your cooker stops working, or worse.
Careful, Kim. Your sarcasm's showing...

Re: Replacing an electric hob
« Reply #3 on: August 27, 2019, 07:34:01 pm »
The hole in the worktop may not match the new hob. That could lead to more work than you thought.

Electrically, it's what Kim said. The "bastard thick cable" will make opening the Big Red Isolator Switch hard work if you have to do that. Actually, any work with the 6 mm2 or 10 mm2 twin and earth is many times harder than little bits of flex, just because it is so bloody stiff and won't go where you want it to, especially in terminal boxes with not enough space.

If the cable is too short, you might be lucky and find that there's an outlet box on the wall and you won't have to thread the bastard thick cable back to the Big Red Isolator Switch.
Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

Re: Replacing an electric hob
« Reply #4 on: August 27, 2019, 07:34:21 pm »
As Kim says, I'd flip the switch at the breaker too, to be sure.

Check the size of the cutout before you shop for a new hob - they are not all the same size (as Kim had said, "They great thing about standards is there are so many to choose from..."). I made up some hardwood mouldings to make up the gaps when I last replaced mine, as it was IIRC. 15mm one way and 20mm the other, smaller than the previous hob.
If it ain't broke, fix it 'til it is...

T42

  • Tea tank
Re: Replacing an electric hob
« Reply #5 on: August 28, 2019, 08:32:16 am »
You might have a bit of phun if the hob & oven are on the same cable and one is single-phase while t'other is three-phase.  When our kitchen was installed the "qualified professional" who did it happily wired the two unused phases together at the hob and was somewhat startled at the bang when he switched the juice on again.

I've dusted all those old bottles and set them up straight.

fuaran

  • rothair gasta
Re: Replacing an electric hob
« Reply #6 on: August 28, 2019, 10:13:49 am »
Thanks, that's useful stuff. I reckon I can have a go at it. Yes, will switch off all the power, just to make sure.
The cooker is at the other side of the room, so don't think its on the same cable.

Yes, have checked the size of the hole.
Think I will go for an AEG hob, with touch slider controls. Maybe less annoying than +/- buttons.
Can't find many hobs with proper knobs, except a Smeg for £600.

Re: Replacing an electric hob
« Reply #7 on: August 28, 2019, 09:26:40 pm »
Don't forget to check that the power is actually no longer being fed to the appliance despite what the switch appears to indicate... ::-)

Re: Replacing an electric hob
« Reply #8 on: August 28, 2019, 11:00:46 pm »
You might have a bit of phun if the hob & oven are on the same cable and one is single-phase while t'other is three-phase.  When our kitchen was installed the "qualified professional" who did it happily wired the two unused phases together at the hob and was somewhat startled at the bang when he switched the juice on again.
Three phase in domestic premises is as rare as hens' teeth in the UK. It's quite common in mainland Europe.
Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

Jaded

  • The Codfather
  • Formerly known as Jaded
Re: Replacing an electric hob
« Reply #9 on: August 28, 2019, 11:08:48 pm »
Yeah, but we’ll be out of Europe soon so that won’t matter at all!

(Speaking as someone who is devastated that he has probably just completed his last journey as an EU Citizen  >:( >:( )
If you don't like your democracy, vote against it.

Re: Replacing an electric hob
« Reply #10 on: September 04, 2019, 04:42:48 pm »
I replaced ours last year after the glass broke.  Our daughter denied all knowledge of how it broke.

Changing it was pretty easy.

The slightly tricky bits were

It was deeper at the back than the original so some work on the aperture was required.

It could run off 3 phase and you had to connect 2 “jumpers”, that were supplied, to the two unused terminals.

fuaran

  • rothair gasta
Re: Replacing an electric hob
« Reply #11 on: September 18, 2019, 06:35:34 pm »
Now done.
First tricky bit was removing the old hob, had some little clips in the sides, so  bent them out with a screwdriver.
Then fitting the cables into the terminals. Had to shorten the wires a bit, so needed some wire stripping.
Yes, a bit of a squeeze to bend the thick cable in the limited space in the terminals.
The new hob uses Torx T20 screws, so needed a suitable screwdriver bit.





All working fine now anyway.

Feanor

  • It's mostly downhill from here.
Re: Replacing an electric hob
« Reply #12 on: September 18, 2019, 06:47:42 pm »
On the second photo, I presume theres a link between L1 L2 and L3, to operate the thing on a single phase supply?
I think I can see the link under the brown Live wire.

I am a wee bit concerned about how that brown Live wire is clamped down.
(And possibly the others too.)
I can see quite a lot of copper above the screw in the pic.
Should the wire not be under a square clamping washer / plate thingy?
It doesnt look securely clamped to me, but it may be the photo.

Or is that the old hob, and the next pic is the new one?
Looks like it is, the fan is dusty.
In which case, yes, the wiring looks tight.

fuaran

  • rothair gasta
Re: Replacing an electric hob
« Reply #13 on: September 18, 2019, 06:59:29 pm »
The 2nd photo is from the old hob. So that's how it was fitted by a proper electrician...
Yes, there is a metal link from L1 to L2. I took that off the old hob, and fitted it on the new hob. Not sure if the new one actually included it, unless it fell out of the box.

I have got the wires pretty well clamped town. No clamping washers, but the screw heads are quite wide, and the terminals have metal up the sides of the screw holes.