Amps - Consumption v Supply

[Thai Amateur]

Yet another thing I can't get my head round - :smug2:
I'm obviously missing something apart from hair and more than a few little grey cells.
When I size up the consumption on the new bungalow I get the following rough consumption figures.
Total possible load - everything switched on at same time - 190 Amps
Worst estimated case - actual - 96 Amps. That's with 3 air cons, oven, 1 water heater and some odds and ends (kettle, TVs, etc.).
However my supply will only be 30 Amps so how does everything still work? 30 Amps is only 7 KW.

My own house has similar electrical stuff and the same supply but we have no problem with overloading.

I've read comments about diversity but even then I can't see how the supply can balance the load.

 

[Badged01]

Sure you've done your maths right as 190A seems a big demand for a domestic bungalow, even if you've got power hungry aircons trying to fight against the roaring electric oven!

But if you're right and your supply fuse is 30A (check you've got one?) then if you are actually drawing more than 30A for any significant time that fuse should 'pop'. It certainly shouldn't be letting you draw 96A for any length of time! If it isn't 'popping' then the likelyhood is that when you have things running as per 'normal', you aren't drawing more than 30A!

You can check what you're actually drawing from the supply with your appliances on using a clamp meter to give you a better indication of your current usage.

 

[Thai Amateur]

Probably over pessimistic with some of the socket loads so I've made some changes. Total load is now 140 Amps.Total of Air Cons, Oven and Water Heaters is still 85 Amps though and I would expect most of them to be on some time or another.
Supply fuse (I think) is in the meter. I know one small unit in the village had a 63 Amp manual switch to connect to the supply (standard in almost all poorer type Thai houses). The guy there shorted something out and the meter blew.
As I said my own house (next door to new bungalow) has similar electrical equipment (Air Cons, Water Heaters, et.) and don't have any problem with the supply even though we run a lot of stuff together.

 

[Engineer54]

Calculating maximum demand just by using appliance and equipment KW ratings, can very easily give you false and/or way off the mark values, ...even in the UK. Even easier when you include 3 or 4 heating/cooling aircon units from 9000 to 24000 btu... lol!!

The fact is, none of those items mentioned are going to be continually on together for any amount of time drawing their maximum load. Certainly the Cooker, Heaters, Air-cons and the like, will all be switching on and off. In effect, you will only see a fraction of the installations connected load being drawn at any one time and for more than a few minutes...

You have witnessed all this yourself in your own house, with roughly the same appliances/equipment, etc, without any of the expected nuisance tripping!! Diversity works, and it works extremely well too ...lol!!

 

[Marvo]

Most circuit breakers and fuses will handle 3 or even 4 times their rated current for several minutes without blowing or tripping.

 

[Thai Amateur]

Calculating maximum demand just by using appliance and equipment KW ratings, can very easily give you false and/or way off the mark values, ...even in the UK. Even easier when you include 3 or 4 heating/cooling aircon units from 9000 to 24000 btu... lol!!

The fact is, none of those items mentioned are going to be continually on together for any amount of time drawing their maximum load. Certainly the Cooker, Heaters, Air-cons and the like, will all be switching on and off. In effect, you will only see a fraction of the installations connected load being drawn at any one time and for more than a few minutes...

You have witnessed all this yourself in your own house, with roughly the same appliances/equipment, etc, without any of the expected nuisance tripping!! Diversity works, and it works extremely well too ...lol!!

Many thanks. Understand now. Too used to the idea of things being either On or Off absolutely. Completely overlooked the auto switching on and of.