Diversity method does it really work

[abwooli]

Hello guys hope u all ok
Hope u can all hlp
I have an oven and hob
Hob =5.5kw size of cable 6mm
Oven =2.3kw
Fuse = 30amp

All appliances are using the same cooker switch with a socket outlet

In the past I have had 2 hobs over heating and burning my worktop.

My question is if am to use the diversity method it will give me 22amp fuse in total for both Appliances. Which will mean the 30ampfuse is ok

But with out using the diversity method I end up with 34amp intotal or 7800w as load to the 6900w for the 30amp fuse.

(So is the diversity method a missing leading idea based on assumption or not ?)

I was thinking of putting the oven off the ring main with a spur fuse 13amp
And leave the hob on the 30amp fuse

Is this the right way to do it.
How would you guys wiring it in to avoid future over loads

 

[winston1]

30 amps is 7200 watts at 240 volts which is most likely what you have and your appliances are rated for. A 30 amp fuse won't blow instantly at 30.1 amps or even 34 amps. You will never use your oven and cooker at full load at the same time. So yes diversity does work. Some will tell you not to put fixed loads above 2kW on the ring, though I personally don't agree, and there is no such reg.

So stop worrying and leave it as it is.

 

[Taylortwocities]

You can easily run both the hob and that oven from the existing cooker circuit.

Guidance says that you should not be putting a fixed load of more than 2KW on the socket of a ring final.

re

In the past I have had 2 hobs over heating and burning my worktop.

That has nothing to do with the electricity supply. It is to do with the hob being faulty and or the worktop bing the wrong type.

Just because a circuit is rated at 30amps does not mean that 30amps is pushed out all of the time. The appliances will pull as many amps as they need.
The maximum amps that circuit could supply is 30amps. You will never get to that. Ever. Even on Christmas Day with everything on full blast.

 

[JohnW2]

My question is if am to use the diversity method it will give me 22amp fuse in total for both Appliances. Which will mean the 30ampfuse is ok .... But with out using the diversity method I end up with 34amp intotal or 7800w as load to the 6900w for the 30amp fuse.

As you have been told, "diversity works", and your two appliances will be fine on your existing cooker circuit (and far better than putting the oven onto your ring circuit).

In fact, even if the 7.8kW total was quoted at 230V (which it almost certainly won't be), by my calculation the after-diversity current would actually only be about 17A, not the 22A you suggest. If, as winston has correctly said is probably the case, it's quoted at 240V (and your supply is close to that voltage), then the 'after-diversity' current will be even lower.

Also, for added reassurance, your 6mm² cable is more than adequate for the oven+hob loads and, even if the current does occasionally rise to appreciably above the calculated 'after diversity' figure, it takes something like 50A to 'blow' a 30A fuse.

Kind Regards, John

 

[abwooli]

Ok guys but both hobs have blown the fuse when Mrs using all the four hob rings and oven at the same time. Both hobs were brand new

@Taylortwocities when you methioned about the guidance regarding the 2kw not to be fixed on the ring where can I get that from ie which book.
Thanks

 

[JohnW2]

Ok guys but both hobs have blown the fuse when Mrs using all the four hob rings and oven at the same time. Both hobs were brand new

That is very surprising. As I recently wrote, it takes around 50A (i.e. around 11kW) to blow a 30A fuse.

@Taylortwocities when you methioned about the guidance regarding the 2kw not to be fixed on the ring where can I get that from ie which book.

It's guidance in Appendix 15 of the IET Wiring Regulations (aka BS7671).

Kind Regards, John

 

[abwooli]

That is very surprising. As I recently wrote, it takes around 50A (i.e. around 11kW) to blow a 30A fuse.
It's guidance in Appendix 15 of the IET Wiring Regulations (aka BS7671).

Kind Regards, John

Thanks pal

 

[abwooli]

Txt

 

[ban-all-sheds]

Hello guys hope u all ok
Hope u can all hlp

Most people prefer proper English words to be used.

 

[JohnW2]

Most people prefer proper English words to be used.

... I can't speak for 'most people', but some people are happy so long as they can understand the intended meaning - I would have a problem with my daughters' text messages if I were not one of those people! This is a internet DIY Electrics forum, not a school.

Kind Regards, John

 

[ban-all-sheds]

It is a place where people come to ask questions, and to communicate.

There is absolutely no excuse for the way that abwooli wrote his post - it betokens a lack of interest in doing a job properly.

If your daughter does not use proper English when communicating with you, call her out on it. Again - there is no excuse, it is just laziness, and not to be tolerated.

 

[JohnW2]

There is absolutely no excuse for the way that abwooli wrote his post - it betokens a lack of interest in doing a job properly.

That's rubbish. Millions of people write like that on 'social media' and in places like internet forums - and that means absolutely nothing about their degree of interest in doing properly a job they are writing about.

You don't like "u", but you're a man who makes (at least in the past) very widespread use of abbreviations and acronyms! You actually 'sucked me in' to that habit in the past, but I have actually now 'gown out of it'.

Kind Regards, John

 

[ban-all-sheds]

That's rubbish. Millions of people write like that on 'social media' and in places like internet forums - and that means absolutely nothing about their degree of interest in doing properly a job they are writing about.

I disagree. You cannot trust people so lazy that they cannot be bothered to type a few more letters to have any interest in doing anything properly.

You don't like "u", but you're a man who makes (at least in the past) very widespread use of abbreviations and acronyms!

Abbreviations and acronyms are one thing.

'u' and 'hlp' instead of 'you' and 'help' are another.


We could go around and around the loop of you trying to defend laziness and a lackadaisical attitude, and me standing up for precision, taking care, doing things properly, but it would do no good, and would be a pointless digression in the topic, so let's not bother. I have higher standards than you, and expect better behaviour from people than you do, and that's all there is to it.

 

[JohnW2]

Abbreviations and acronyms are one thing. ... 'u' and 'hlp' instead of 'you' and 'help' are another.

The difference seems pretty subtle to me.

None of this is as 'new' as some people seem to think. I was 'brought up', 50+ years ago, to use morse code to communicate. The 'language' we used, to minimise (morse) keystrokes, was very similar to 'text-talk' - with omission of many vowels and a good few redundant consonants it certainly included "u" and "hlp".

Kind Regards, John

 

[abwooli]

Most people prefer proper English words to be used.

@ban-all-sheds bless you pal
There is always one out there in life. Will stir things up