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Rules on Spurs

Airconditioningman

Sorry in advance if this is a silly question, but I’m having a few issues with the electrics on an Air Conditioning install in England. The installation is on a domestic property and the house is very large which means that it’s incredibly impractical to run a new cable as the architects made sure to use all available space as living space so there are no voids or attics that can help us.

My question is, what is the maximum amount of power that we can take from  ring main that has no existing spurs on it please. I know we can have a 13a fused spur, but is there any way to get more than 13a without adding a new circuit please? The electrician is saying that 13a is the maximum, but I always thought that t was a little more. 

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    Worth checking the MI (Manufacturers Instruction) as a lot of AC units need a didicated circuit with localised rotary isolation.  What is the max power consumption of the unit?  Could be 15 to 20 amps.  Also the breaker type recommended could be a type F or B to deal with the inrush current.  Remember MCB trip and RCBO mA trip are different characteristics.  Also factor in the volt drop calculations if use 2.5mm2 CSA and make note of any thermal derating as well as Earth leakage to not exceed 30mA.

    If all good then 1 spur off a Ring Final Circuit COULD be OK.  its loaded with Caveats. 

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  • 0

    Worth checking the MI (Manufacturers Instruction) as a lot of AC units need a didicated circuit with localised rotary isolation.  What is the max power consumption of the unit?  Could be 15 to 20 amps.  Also the breaker type recommended could be a type F or B to deal with the inrush current.  Remember MCB trip and RCBO mA trip are different characteristics.  Also factor in the volt drop calculations if use 2.5mm2 CSA and make note of any thermal derating as well as Earth leakage to not exceed 30mA.

    If all good then 1 spur off a Ring Final Circuit COULD be OK.  its loaded with Caveats. 

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