Is the flexible cable big enough?

[Wayne Phillips]

Dear Forum....

My kettle connects to the mains via a 3-core 0.75mm^2 flexible cable that is about 75cm long. This was the cable that came with the kettle.

The power rating of the kettle is from 1800-2200 Watts, which means it is drawing between 7.8 and 9.6 amps (using nominal voltage of 230V)

The wiring regs state that a 0.75mm^2 cable has a maximum current carrying capacity of 6 amps.

Then why is the cable supplied not 1.00mm^2 instead...which has max c.c.c. of 10 amps?

Thanks to all.

Wayne :smilewinkgrin:

 

[Clive P]

Hi,
I believe cable length will be taken into consideration here, but I may well be corrected on that.

Regards.

 

[Clive P]

Hi,

Also the length of time the load is applied.

Regards

 

[Wayne Phillips]

Hello...I thought that c.c.c. could never be exceeded. Also, I thought that cable length only came in to play when considering voltage drop in installations.

So, what you are saying is that because of the load operating for a short time and a short cable length...it isn't really an issue??

Thanks

 

[telectrix]

not the only situation where flex on appliances is undersized. i came across a 2kW downflow heater (which can be running for hours at a time) fitted with 0.75mm flex, fed from a 13A FCU. manufacturers instructions stipulated a 13A fuse, so it's a case of us sparks abide by the regs. but these idiots do as they please.

 

[Guitarist]

Saves the manufacturers a few quid over millions of units. Totally agree tel, we have to follow rules which include safety margins, whereas they take them to the limit.

 

[HandySparks]

I've noticed this too. Kettle cables often appear to be undersized. I understand that the tabulated cable ratings are largely determined by the rate of degradation of the insulation when run at the rated current for long periods. Due to thermal inertia, cables take a while to reach their maximum temperature when at full load. When used for a kettle, which will only be loaded for a couple of minutes at a time and unlikely to be used more than a few times per hour, the manufacturers can get away with a lower rated cable. Also, modern kettles seem to have a limited lifetime and will probably have failed and been chucked away before the cable insulation degrades too far.

 

[Guest55]

even at a full 13a it will still take that .75 flex an hour to warm up
not really a problem for a 2 minute boil kettle.

plus the fact that appliances and factory assembled equipment do not need to follow the CCC guidelines in bs7671 , other standards are followed for product safety compliance

 

[Paul.M]

:stupid:

A flex is not fixed wire so 7671 does not apply. ​

 

[Silly Sausage]

:stupid:

A flex is not fixed wire so 7671 does not apply. ​

Spot on...different kinds of current.
That's why we have Periodics (GN3) for Fixed Wiring, and ISITEE (and its CoP) for equipment connected to the aforementioned fixed wiring.

 

[Guitarist]

Totally agree...different type of electricity if the wiring isn't clipped....

 

[Rockingit]

You'll probably find the answer to the OP's Q is much simpler: the manufacturers of the kettle will have taken the spec for the cable from it's makers, not from some generic worst case scenario table. If you actually do the full cable calcs yourself and apply every derate component accurately you'll probably find you get a very different answer!!

 

[SPARTYKUS]

Have you checked this said flex, theres a slim chance it may be pure gold, in which case I think we're all okay.