Exceeded max demand questions

[Lekky1]

Hi guys, I have been asked to fit a ring main in a utility room currently being built with a outside socket and a lighting circuit with 4 led lamps and a outdoor light, this much I am comfortable with.

My issue is with the max demand,
The current consumer unit is loaded to the max with 212amp of mcb's
With a 60amp cut out fuse

So if I do the math 212a -40a x0.4 +40a
Gives me a maximum diversity of 108.8amp

So I'm already nearly twice my max demand already before I've started adding my circuits.

It's a 2 bed small bungalow, this seems hugely over rated, I would like to get my 1st NIC assessment done on this so i want to cover all bases.

So any ideas would be gratefully received, my thoughts would include
1. Request DNO to upgrade to 100amp cut out which would still not meet the criteria,

2. Test and possible down grade any overrated mcb's, there is five circuits for sockets????

3. Full load test

4. Could I apply diversity to each circuit independently ?

Here is the C.U and cut out

 

[Andy78]

Work out the max demand on what is used and connected instead.

If the sockets were arranged on one circuit instead of five would the actual use be less ? If there were 8 circuits would the actual use be more ?

How will downgrading the circuit breakers help the actual use of the installation ?

 

[buzzlightyear]

1. Request DNO to upgrade to 100amp cut out which would still not meet the criteria,

you have got no chance on that .can you not alter any of the circuits to make ring .

 

[buzzlightyear]

is their no way of sorting the main board .

 

[Lekky1]

you have got no chance on that .can you not alter any of the circuits to make ring .

That was what I meant on option 2, I haven't seen inside the C.u yet but I can only imagine the majority are run separate in radials, it would possibly undertake some destruction to convert to ring circuits unless I was very lucky but could be a viable option

 

[Strima]

Average night with the lights on, TV going etc you'd be lucky if that hits 10 amps. Add another 40 maximum if the shower is running.

 

[Baddegg]

Listen to Andy mate,diversity is not just about that single calculation....for instance if 1 lighting circuit is 6a mcb but has 7-8 points at couple of watts (leds) you’re not realistically ever gonna reach 6a,even if you put 100w bulbs in......
You’ve also got 4 radial circuits totaling 72a with 5 sockets on...

 

[Lekky1]

So should I just perform a full load clamp test or just factor the usage from what is connected?

 

[Gavin John Hyde]

I get why you are fretting over the max demand if you will be taking the NIC guy round on your first assessment but in my experience I have never been asked once about demand etc... they do have some common sense. In anycase think about it for a moment... has the fuse blown with what is currently there?

 

[Baddegg]

That’s up to you mate,but bare in mind that you are the one that has to justify your decision and calcs should the worst happen.......engineering judgement my tutor used to call it....I think you’ll be pleasantly surprised if you clamp it though

 

[Strima]

SWAG = scientific wild arsed guess

 

[Baddegg]

SWAG = scientific wild arsed guess

We just put an ish on the end of everything......that’ll be fine ish....

 

[Lekky1]

I know it's just a small bungalow with the usual domestic appliances that would never even come close to the max demand of the value of mcb's , especially with the old couple that live there, so If I do clamp test and see and prove I have adequate room for movement , would I create space for new socket circuit or just run a sub main?

 

[Andy78]

I know it's just a small bungalow with the usual domestic appliances that would never even come close to the max demand of the value of mcb's , especially with the old couple that live there, so If I do clamp test and see and prove I have adequate room for movement , would I create space for new socket circuit or just run a sub main?

You could alter the original circuits as long as you tested and provided certification.
Where would you be running a sub main from and to ?

 

[Baddegg]

Are any of the 4 radials near to the new utility room?....

 

[JAWS]

Are you member of any CPS schemes Lekky?

 

[Baddegg]

Are you member of any CPS schemes Lekky?

Thinks he’s using this job as entry to a scheme massive...

 

[Lekky1]

Are any of the 4 radials near to the new utility room?....

The hall socket is about 7ft from utility, and the bedroom socket is right next to utility

 

[buzzlightyear]

The hall socket is about 7ft from utility, and the bedroom socket is right next to utility

make the ring from there if you can .

 

[Lekky1]

Are you member of any CPS schemes Lekky?

I'm am joining NIC