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3 phase supply upgrade required?

Jimi

Do you think the following installation would require a 3 phase supply upgrade? Here are the calculations based on the on site guide maximum demand table:

6A lights down – 66% = 4A.
6A lights up – 66% = 4A.
6A smokes – N/A.
20A sockets down – 40% of others = 8A.
20A sockets up – 40% of others = 8A.
32A sockets kitchen – 100% of largest = 32A.
32A oven and hob – 10A + 30% remaining (35A – 10A = 25A * 0.3 = 7.5A + 10A) = 17.5A.
45A water heater 1 (10.1kW) – 100% of largest = 44A.
25A water heater 2 (5.4kW) – 100% of second largest = 24A.
32A garage – 1 rad (9A), sockets (40% of others = 8A), lights (66% = 4A) = 21A.
25A or 61A heating – no diversity allowed = 25A or 61A.

Total = 188A or 224A (depending on electric radiator choice).

If the table was used seriously for every installation then nearly every house would be over the 100A standard, don't you think? But this is an all electric system so is particularly demanding of energy.

Thanks!

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    I did a diversity calculation for my house it came to 140A, no electric heating. I then added a 9KW pool heater which ran flat out for weeks at a time, thankfully long since gone. It ran OK on  single phase 60 A fuse on the submain from the garage. When replacing the TP board in the garage I also replaced the switch fuse to the house and it was obvious the 60A fuse had been hot at some point but had not blown or melted anything. Despite ordering and paying for a 80A per phase supply I found out years later the supply was fused at 60A per phase.

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  • 0

    I did a diversity calculation for my house it came to 140A, no electric heating. I then added a 9KW pool heater which ran flat out for weeks at a time, thankfully long since gone. It ran OK on  single phase 60 A fuse on the submain from the garage. When replacing the TP board in the garage I also replaced the switch fuse to the house and it was obvious the 60A fuse had been hot at some point but had not blown or melted anything. Despite ordering and paying for a 80A per phase supply I found out years later the supply was fused at 60A per phase.

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