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

 

[buzzlightyear]

'm am joining NIC

bad move ,tin hat on and flack jacket on .

 

[Rpa07]

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

I thought you was being ‘down with the kids’ then Ken!

 

[Lekky1]

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 ?

Sorry not sub main, thats the next ball game later down the line , I meant a board extension cu

 

[Lekky1]

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

Yes, that's the plan fingers crossed

 

[Lekky1]

bad move ,tin hat on and flack jacket on .

What's wrong with that? Any better schemes, its the only one I have been recommended so far

 

[Lekky1]

make the ring from there if you can .

Convert the bedroom radial into a ring? And assumably upgrade mcb from 16a to 32a ?

 

[JAWS]

Are you member of any CPS schemes Lekky?

Yes, that's the plan fingers crossed

Good Luck I am sure you will fine.

 

[buzzlightyear]

Convert the bedroom radial into a ring? And assumably upgrade mcb from 16a to 32a ?

it depends how the lay out is, you could incorporate if possible the socket to the ring ,but how many socket for the utility room .

 

[Deleted member 26818]

I see a Niglon CU and a Proteus isolator.
I foresee issues over costs.

 

[Lekky1]

it depends how the lay out is, you could incorporate if possible the socket to the ring ,but how many socket for the utility room .

5 double sockets & 3 fused connection units down to appliance singles

 

[telectrix]

move the 1x socket over to the 2x socket MCB. (16A). then replace the redundant MCB with a 32A. then install your new RFC from that.

 

[telectrix]

I see a Niglon CU and a Proteus isolator.
I foresee issues over costs.

what's wrong with that? the proteus isolator is not part of the CU so mixing of makes is not relevant.

 

[Nigel]

When did this lazy approach to diversity come in to force? When I was an apprentice you looked at what was actually installed, not counting MCB values and doing a calculation on those.

 

[telectrix]

always use the formula:

add up the breakers total rating, multiply by √3, then divide by ∏r², where r is the total of wives and teenage daughters who use shower for hours on end.

 

[Lekky1]

When did this lazy approach to diversity come in to force? When I was an apprentice you looked at what was actually installed, not counting MCB values and doing a calculation on those.

It's the wet blanket culture we live in now mate

 

[ackbarthestar]

IMO I would clamp the incoming phase (or neutral) and get some actual readings as from what you have told us your theoretical demand and diversity is way over the top. We know that small domestic installations use on average between 20 - 60% of their maximum demand over the 24hour period. Also, It will depend whether or not you have any instantaneous water heaters installed....

 

[Lekky1]

IMO I would clamp the incoming phase (or neutral) and get some actual readings as from what you have told us your theoretical demand and diversity is way over the top. We know that small domestic installations use on average between 20 - 60% of their maximum demand over the 24hour period. Also, It will depend whether or not you have any instantaneous water heaters installed....

I believe the only instant water heater is the shower, I will double check, I will perform a clamp test on Sunday when I'm back there to get a true picture

 

[Deleted member 26818]

what's wrong with that? the proteus isolator is not part of the CU so mixing of makes is not relevant.

It’s not mixing that’s the proble.
It’s the cheap tat that’s the problem.

 

[Toneyz]

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?

Also is there any signs of thermal damage to the meter tails?

 

[Lekky1]

Also is there any signs of thermal damage to the meter tails?

No the tails look mint