Service cut out

[Sparky18]

Hey i am new to this i am studying C&G 2330 at college.
I am trying to work out the maximum power of demand in my house and it works out to 31,460W. I am now trying to calculate the total current and im doing this by assuming my house runs on a 230V supply and the total current works out to 137A but the main service cut out is only rated up to 100A but on the service cut out its a Eagle Lucy 415v n does not say the rating of it can some one help me on this?
Many thanks

 

[JohnD]

Have you got to the "Diversity" chapter yet?

 

[Sparky18]

What is the diversity chapter? Im all new to this sorry

 

[davy_owen_88]

Well first off, you need to take diversity into account. Not everything will be running at the same time so your 137A will probably be less than half that for the majority of the day.

Another point to remember is that a 100A BS1361 fuse will take more than 100A for a consideral amount of time before it will actually blow.

 

[Sparky18]

Ok thanks for that i didnt take them points into account

 

[Adam_151]

Heres a question for you! when the electricity company installs transformers and main street mains for a housing estate, what do you reckon they assume for the loading of say a 4bed house with central heating? (and then obviously this gets multiplyed by number of houses to work out what size transformers and cables have to be)

So any guesses?

 

[RF Lighting]

Me sir, I know!!

 

[Spark123]

Oh no you don't

 

[davy_owen_88]

I know too Well I think I remember someone (might have been you) posting it.

 

[plugwash]

i don't remember the exact figure but its less than a kilowatt iirc.

of course that is the loading per house for a large system. Smaller collections of houses presumablly have to allocate a lot more capacity per house on the transformer because of the bursty nature of domestic power use.

 

[Adam_151]

Actually the figure I have is around two kilowatts, and I assume that only applies to housing estates of at least a reasonable size, rather than a transformer up a pole feeding 4 farm houses.

It might seem a lot of diversity to apply, but if you look at your electricity bill and work out the average, unless you are growing dodgy stuff in your attic it will be a lot less than 2kw, and they do use an averaging period of half an hour

(and if everyone does switch their kettle on after the end of the soaps, then the overload will only last for five minutes or so, and the thermal mass of all that metal and oil in transformers can take it, similarly cables either bare in free air, or buried in thermally conductive ground can take the short term overload)

 

[davy_owen_88]

10A per household is the figure I have heard thrown around.

 

[ricicle]

I agree with the 2 Kw demand per household.I was told this by a local network planner