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APSH

Hi guys, Just after some pointers. Looking to update fuseboard to my sisters property, needed a d/p isolator that was installed, and electricity board said main service head is porcelin and will need changing or new supply to propery as the original supply is looped from next door. most likely new supply. Now they are saying that under ofgem rules they can only change service head and will only give me a like - for - like and it will more than likely be a 60A supply. I am now unsure as what to put on the cert as I have calculated max Demand as 94 A and so this will not look right on the cert. I did point this out but was told that under the ofgem rules they are only allowed to replace like-for-like. If I wanted a whole new supply it would cost £1000's, and my sister just don't have the money. Just wondering what I could put on cert as I wanted to use this for assesment but don't want to get pulled on it.
thanks for answers.

APSH
 
Contact OFGEM yourself and get those rules quoted from the horses mouth ...so-to-speak!!! One thing is for sure, It won't say that the DNO can ONLY supply like for like!! This is the DNO offering the absolute minimum, to undertake replacement work, that should have been completed nation wide a couple of years ago. They are basically making savings on their own behalf and/or, trying to make a few bucks out of you.

As for only giving you a 60A supply, that very much depends on the size and type of property. I was under the impression that for a standard sized house supply, it was now an 80A service fuse in a 100A service cut out, with a service cable of not less than 25mm for all new supplies, which yours will be, unless they are intending to leave the original cables in place. The Service cable looping through the service cut-outs, isn't a problem, so long as the incoming cable is of a suitable CSA to supply both properties. They still use this looping method today, to connect whole streets of house properties, saves on road take-off joints... lol!!!
 
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Hi guys thanks for reply.

The house is 3 bed terrace and they want to keep origianl cables and just change the service head. Calculated Max demand as 40% of all mcb's and 100% of biggest mcb. They did not tell me size of porcalin fuse and no writing on the carrier. just said that they will replace like for like but the fuse is more than likeliy a 60A and this is what I will be given under OFGEM rules. Just worried if my max Demand is 94 and new fuse is 60 A I may be pulled up on it by assesor as this is for part p assesment. Was thinking of putting on cert that they would only supply a like-for-like which is a 60A . I am hoping it is either a 80 or 100A but from talking to one of the guys at the company today on the phone they seem sure that it will be a 60A. Unfortunately this is the only job that I can show the assesor and so need to cover my corner. Thanks for Any advice.

APSH
 
If the installation has always had a 60amp service fuse and the loading in the house hasn't changed, then I'd re-visit your maximum demand calculations!
 
Agree with above, switch on all major loads and clamp it. This will give you a reasonable assessment of the maximum demand. 94 amp seems high if it's a normal 3 bed house
 
Would clamp it but the problem is my sister has moved out to live with me and my parents due to my mothers deteriorating health and wants to sell the house and has brought all the appliances with her to our house. so would not get a valid reading at her old house as there is nothing there. I know it seems high but if I used the method in the on-site guide it is even higher. Just don't want to fluff the assesment.
 
Stop fretting APSH,the assessor will not likely give a monkeys what supply fuse you have,the maximum demand is also to a certain extent an abitary figure

If you want to be assessor immune,then state 60 amp in line with the rating of the fuse
If by some remote possibility he asks you how you arrived at the figure,tell him it was a measured assessment when loads were vavailable

The maximum demand when calculated using the installed mcbs can give ridiculously high figures if the installer has been a good boy and installed plenty of seperate circuits

Don't worry about the supply capability,I'm sure any remote future problem of lack of capacity wont come back on you,
 
If your just worried about what's written on a form, make a new one out, ...not the end of the world is it!!!

Where my parents lived in Essex, the then Leccy board changed all the service fuses from 60A to 80A as a matter of course when they changed the original meters (rated at 45A) for a new ones.(this was years ago, so not a digital meter)
Which just goes to show the diversity values of typical households. Apart from cooking and heating we were quite electrical appliance orientated. ...lol!!!
 
The problem with calculating maximum demand is the fact that most houses how have fuse boards with far more breakers than they used to.

If the property doesn't have a power shower I'd venture to suggest that the peak demand would be around 45A at the very most.
 
Don't worry about the cut out size. not your concern. If its 60 and your calcs are higher, so what? As long as its lower than the rating of the c.u main switch. Thats why you use the 40% rule when working out max demand. If you did it per regs book youd have an even higher number. The fuse will never blow Just think who would pull 94A anyway unless they have a load of storage rads.
 

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