Induction Hob Issues

[Eric The Viking]

It looks like the wires are in the correct places, but, given the current required, those actual connections look nasty.

The bare copper ought to be properly grabbed (caught up) by the terminal post or at least a brass/plated washer on top. There is too much copper showing. I suspect either those connections or the cable or the other end (where it connects into the spur) are high enough resistance to limit the current (or drop the voltage, to express it t'other way round). That said, 2.5mmsq ought to be enough copper for this (in the cable), as 3kW is only roughly 13A.

A far better way to do it, both neater and electrically better, is to crimp eyes to the ends (either circular or U-shaped), and then attach those to the actual terminals. You need a properly set up crimp tool, but it's theoretically a better connection even than soldering.

I'd see if you can improve the connections in the hob, and/or the spur box too, just in case. If that doesn't do it, thicker cable might help. You could test that by doubling up the cable temporarily and doing your test again.

I agree with the other posters who've said the only variable is the hob. If you have used the same pan and the same amount of water, and you workshop one is supposedly lower power, yet the water boils in significantly shorter time, something isn't right.

 

[Distinterior]

As the Hob is rated at 7.4 kw, I would have fitted a larger cable than the 2.5mm csa cable that you show in your pictures and I would have also used crimp eyelets as Eric has suggested. Those connections do not look good!

EDIT.
I cant be certain that this would solve your problem, but here is a link to a set of pans sold by AEG for their Induction Hobs....

https://shop.aeg.co.uk/Cooking/Cookers- ... 9029798205

 

[Deejay]

Afternoon all

I'm not a qualified spark. 7.4 Kw equates to about 32.17 amps - call it 33 .

The cable you have identified has a current carrying capacity of 25 Amps according to ...

http://www.sparkydirect.co.uk/product/2 ... index.html

This is a 'best case' scenario. In practice the safe capacity may be less.

The manual from AEG says ...

8.3 Connection cable
• For a single phase or two phase
connection, use the cable type:
H05BB-F or H03V2V2-F which
withstands a temperature of 70°C or
higher.
• To replace the damaged mains cable,
use the cable: H05BB-F or H03V2V2-F
which withstands a temperature of
70°C or higher.

This specifies the type of cable. I can't find a supplier of this cable thicker than 2.5 sq mm.

I'd email AEG to confirm that 6383TQ cable is suitable and get confirmation of the minimum CSA requirement.

Crimped terminals would be best as mentioned above.

If the connections you have shown were made by a 'professional' I'd get a qualified spark in to check the rest of the work.

Cheers

Dave

 

[Distinterior]

Here you go.....

https://www.tlc-direct.co.uk/Products/C ... RkOkBZsojF

 

[flying haggis]

if you do recable the hob, can I suggest you use this style of ring crimp (with heatshrink)and not the "automotive" red/yellow insulated

https://www.ebay.co.uk/itm/Crimp-Termin ... SwUPZbPv79

 

[J_Ashley]

Many thanks to everyone for the recent advice – much appreciated.

I appreciate the existing cable size and installation technique will likely be limiting the hob substantially, but is it likely that poor that it is giving lacklustre performance when just operating a single 3200W ring?

Here you go.....

https://www.tlc-direct.co.uk/Products/C ... RkOkBZsojF

To test for improvement (and helpfully resolve), I will purchase the appropriate length of the wire and replace the existing, at the same time making the connections with crimp eyelets.

I assume I am going to want to crimp at both ends; both into the hob, and out of the MCB?

if you do recable the hob, can I suggest you use this style of ring crimp (with heatshrink)and not the "automotive" red/yellow insulated

https://www.ebay.co.uk/itm/Crimp-Termin ... SwUPZbPv79

What is the advantage of that style of crimp terminal over the other?

 

[Distinterior]

"I assume I am going to want to crimp at both ends; both into the hob, and out of the MCB?"

Sorry,... I'm a bit confused by that statement.

Out of the MCB.....??? Surely, the MCB is in your Fusebox/Consumer Unit and then another cable runs from the MCB to a switch near the Hobs location and the Hob cable flex connects to that switch? How else would you be able to isolate the Hob locally?

That Hob cable flex doesn't run all the way back to your Fusebox does it ?

 

[J_Ashley]

Apologies, my ignorance has probably meant I confused terms, making the situation unclear.

The hob is connector to a nearby isolator switch - that is what I was referring to when enquiring whether to use crimp eyelets at both ends.

The cable running into that isolator switch then runs back to the fuse box (or so I believe).

 

[Distinterior]

Okay.

The switch terminals will be perfectly okay to connect to without any kind of crimps on the cable flex. The terminals will be different to those on the Hob connections.

 

[flying haggis]

flying haggis wrote:
if you do recable the hob, can I suggest you use this style of ring crimp (with heatshrink)and not the "automotive" red/yellow insulated

https://www.ebay.co.uk/itm/Crimp-Termin ... SwUPZbPv79

What is the advantage of that style of crimp terminal over the other?

personally speaking I prefer a crimp that "squashes " the cable by folding into the conductor(this you tube video shows the idea)
https://youtu.be/Bmiw8HIWj4A?t=189 You also have the chance to add a bit of solder to improve the connection which you cant do with others

obviously there is a ring not a spade connection and you can see if it is a good crimp unlike the ones covered in red or yellow plastic

 

[sunnybob]

A word of caution here. before installing a larger cable from the wall switch to the hob, Check what cable is there from the consumer unit mcb to the wall switch. Your sparkie has obviously not understood the needs of that hob.
It can be very dangerous to run heavy current through a smaller wire.

The cable should be the same all the way from the main consumer unit to the hob. Also, if youre going to fit ring connectors to the hob, it wouldnt hurt to fit pigtail connectors to the wall switch.
On an electric circuit, the danger is always at the one joint that isnt completely tight and secure.

 

[J_Ashley]

A word of caution here. before installing a larger cable from the wall switch to the hob, Check what cable is there from the consumer unit mcb to the wall switch. Your sparkie has obviously not understood the needs of that hob.
It can be very dangerous to run heavy current through a smaller wire.

The cable should be the same all the way from the main consumer unit to the hob. Also, if youre going to fit ring connectors to the hob, it wouldnt hurt to fit pigtail connectors to the wall switch.
On an electric circuit, the danger is always at the one joint that isnt completely tight and secure.

Thanks for the additional advice. I'll try and check what is running from the fuse box to the hob wall switch tonight.

I'm intending to use the 4.0mm Butyl cable as previously recommended on this thread (below link) to go from the hob wall switch into the hob. Does the fuse box to wall switch cable need to be this specific heat resistant cable, or just large enough to safely carry the required current? We specified that the hob was 7.4 kW and would need a 32a supply, so I'm hoping I see the installed cable is something that can operate safely at that capacity.

(https://www.tlc-direct.co.uk/Products/C ... RkOkBZsojF)

 

[flying haggis]

from the consumer unit aka fuse box ordinary 6mm twin and earth is ok to the wall switch

 

[J_Ashley]

The cable running between the fuse box and hob wall switch is:

CMK BASEC Electric Cable BS 6004 6242Y H 2x6+2.5mm 300/500 V CE 2016.

I'm assuming this is a standard 6mm twin and earth, so we should be ok with regards to that component?

 

[flying haggis]

if it is 6mm t&e no problem. but I cant work out from your description is it 6mm or 2.5mm ie you quote "2x6+2.5mm " are you reading the description from the cable or the box it came in. if the latter have you confused 25m with 2.5mm

 

[J_Ashley]

I'm reading it off the cable, and I've checked again and it definitely reads 2 x 6 + 2.5mm. Unfortunately I don't have any box/packaging, so it's not possible to check there.

 

[Distinterior]

The 2 x 6 is for the 6mm CSA Live and Neutral conductors and the 2.5mm is the bare earth conductor......

6242Y is Twin & Earth.

 

[flying haggis]

I forgot that the earth is much smaller, hence the 2.5

 

[Phil Pascoe]

Incidentally - if anyone's thinking of getting an induction hob or a cooker with one, go for it. I got ours four years ago as we're nowhere near mains gas and didn't want bottled gas heating. Brilliant - I wouldn't even go back to a mains gas hob as the induction hob is as quick if not quicker and a whole lot easier to clean. The only downside is having to use magnetic stainless steel or iron pans. Most of our stuff was Le Creuset anyway, so no big deal.

 

[Rorschach]

Incidentally - if anyone's thinking of getting an induction hob or a cooker with one, go for it. I got ours four years ago as we're nowhere near mains gas and didn't want bottled gas heating. Brilliant - I wouldn't even go back to a mains gas hob as the induction hob is as quick if not quicker and a whole lot easier to clean. The only downside is having to use magnetic stainless steel or iron pans. Most of our stuff was Le Creuset anyway, so no big deal.

I can second this. We currently use a 2 ring portable induction as the fitted cooker is electric ceramic and I hate it with a passion. Will never go back to using anything else now.