Maximum demand calculation

[yarcyk]

Hi.

Question regarding maximum demand calculation.

I have a customer which wants to have a second kitchen fitted in the house. Is this at all possible?
There are two consumer units in the house.
One which has following circuits:
oven 40A
hob 32A
ring basement 32A
ring gtound floor 32A
ring 1st floor 32A
ring 2nd floor 32A
ring 3rd floor 32A
ring outside 32A
water heater 16A

other board:
lights basement 6A
lights ground floor 6A
lights 1st floor 6A
lights 2nd floor 6A
lights 3rd floor 6A
outside lights 6A
doorbell 6A


Electric water heater is only a back up as gas boiler is normally used.
As it sounds like a big house it really isn't. There is only one big room on each floor, and one kitchen in the basement.
It looks like there is 4-5 sockets on each floor, 2-3 lampholders on each lighting circuit.
Cut out fuse is 100A.
Based on mcb ratings it would not be possible, but if you count every single power point and check what is likely to be used for I think it might be possible.
Also, can calculations be made based on current use of the house ( one lady lives in the house on her own). Unlikely that both kitchens would be used at once. (2 double ovens, 2 hobs)

And to make the thing worse she wants induction hob in her new kitchen.

How would you make calculations and use diversity to see if there is a chance of putting new kitchen in.

I am really interested in fitting new kitchen for her , but as I am now preparing myself to be part P registered I would like to know how you would approach the problem.

 

[telectrix]

bet if you turned everything you can think of and clamped a tail, you'd get nowhere near 100A. just get on with it.

 

[GMES]

^^^^^As above

 

[ferg]

This kind of calculation mostly comes down to experience.

Tel has bags of it and will be right.

If in doubt do as he suggested turn everything on and clamp a tail.

You then have to consider the chances of both kitchens being at maximum load at the same time.

 

[telectrix]

for example. in your OP, you have oven 40A, hob 32A. that's 72A. both together, you'd be hard pushed to see more than 22A with them both full on.

 

[yarcyk]

I know it wouldn't be a problem, just to have it all right. As this is listed building there will be architect and Buiding Control inspector involved, so in case there are any questions asked how to convince him?

Also for the purpose of certification some calculations should be done? Who is really to be pleased with results? Building inspector?

Using a clamp on the tail would be a method?

 

[ferg]

The person to be pleased is the person undertaking the work.

The buck stops with them.

 

[Knobhead]

What do colleges teach these days?

 

[davesparks]

What do colleges teach these days?

Health and safety, literacy, numeracy, basic computers, health and safety, how to wire a few things on a wooden wall, health and safety, risk assessments, method statements.
And if there is time a little bit about electricity.

(This is only my experience of the modern apprenticeship, others may have escaped any mention if electricity)

 

[davesparks]

To answer the OP,
You could calculate the maximum demand based on the diversity tables combined with some common sense.
But since you have it all there already you could just carry out a load study to get exact figures.

 

[Octopus]

I know it wouldn't be a problem, just to have it all right. As this is listed building there will be architect and Buiding Control inspector involved, so in case there are any questions asked how to convince him?

Also for the purpose of certification some calculations should be done? Who is really to be pleased with results? Building inspector?

Using a clamp on the tail would be a method?

Hum..... listed building, adding a "2nd kitchen".... alarms bells.

Is the intention to have 2 seperate dwellings? - if so you should be looking at a rewire to ensure that the circuits are completely seperate between them....

Need far more information...

 

[Lucien Nunes]

Based on mcb ratings it would not be possible

Based on MCB ratings it's a b****y loud doorbell!

 

[shanky887614]

Based on MCB ratings it's a b****y loud doorbell!

lol, there was a guy that modded his radio to use a air horn.

pulled around 6amp i believe lol

 

[yarcyk]

There is no intention to have 2 separate dwellings. I would not be possible.
It would be just more convenient location for new kitchen that is is now. However the original kitchen remains in place so it might be used every now and then.

 

[Knobhead]

I’ve just looked though your previous started threads.

Go back to college. You’ve a lot to learn.

 

[yarcyk]

I 'd rather learn from people with a lot of experience. I know there is a lot information in books, but applying them in life is a matter of experience. That's why forum like this one exists.

 

[Knobhead]

Forums weren’t set up to do your work. As I recall they are for genuine tradesmen to help each other.

If you’re not competent to do the work, don’t take it on.

Looking back through your previous questions I stand by what I said, go back to college.

 

[yarcyk]

I agree with you Tony. I know I've a lot to learn. I don't feel confident enough yet to undertake electrical work myself. As I mentioned earlier I am interested in fitting new kitchen and would get electrician to do electrical work. But I wanted to know if this can be done and at the same time learn something rather than just take a yes or no for an answer.

 

[shanky887614]

I agree with you Tony. I know I've a lot to learn. I don't feel confident enough yet to undertake electrical work myself. As I mentioned earlier I am interested in fitting new kitchen and would get electrician to do electrical work. But I wanted to know if this can be done and at the same time learn something rather than just take a yes or no for an answer.

a kitchen is notifiable under part p mate so no

 

[telectrix]

i think what he meant was ... can this be done without upgrading the supplier's fuse.

 

[Simonslimline]

a kitchen is notifiable under part p mate so no

Please correct me if i am wrong but a kitchen is no longer classed as a special location?

 

[shanky887614]

Please correct me if i am wrong but a kitchen is no longer classed as a special location?

its notifiable work under part p and as opening post isnt part p registered or signed upto a scam he wont comply unless he pays labc

 

[Simonslimline]

its notifiable work under part p and as opening post isnt part p registered or signed upto a scam he wont comply unless he pays labc

Surely its only notifiable if new circuits are installed.

Also is it not the responsibility of the person ordering the works to notify LABC? Obviously they would need to be made aware of this by the electrician.

Again happy to be corrected on this

 

[Richard Burns]

Surely its only notifiable if new circuits are installed.

Also is it not the responsibility of the person ordering the works to notify LABC? Obviously they would need to be made aware of this by the electrician.

Again happy to be corrected on this

You are correct on the notification.
For electrical work, in England, in a kitchen, where that work is modifying circuits only, this is not notifiable.
Changing consumer units and adding any new circuits (as identified in the OP) would be notifiable.

 

[cprfenom]

What do colleges teach these days?

How to **** off grumpy men :6:

 

[Tony Johnson]

The BS7671 (wiring regulations) has information in the guidance notes 1 (Selection & Erection)

Appendix H has the following information for a maximum demand calculation

Lighting :- 66% of total lighting load
heating :- 100% up to first 10 amps plus 50% of remaining heating load.
water heaters (instantaneous) :- 100%of largest and 2 largest appliance plus 5% of remaining
Water heaters (Thermostatically controlled) :- No diversity allowed

Cooker :- 10amp plus 30% of cooking appliances in excess of 10amps plus 5 amps if a socket is
incorporated into the cooker control unit.

Floor warming :- No diversity allowed
Thermal storage heaters :- No diversity allowed
Socket circuits - 100% of largest load (13 amps) plus 40% of all other sockets connected
Radial circuits :- 100% of largest load (13 amps) plus 40% of current demand of every other circuit


Work through each circuit using the actual connected load not the MCB or fuse size.

 

[GMES]

Tony this thread is over a year old so I'm closing it.