Power supply for a 5kW (14.6A) multi outdoor A/C - is a dedicated circuit required?

[jimmybb]

Hi -

My friend it looking at having an 2.2kW Electric (5.2kW heat) multisplit inverter-type AC installed. The unit spec has a max-current listed of 14.6A, and has 20A fuse (attached). The nominal running current for the unit is expected to be 5A, and the Daikin data sheet for his configuration suggests a peak of 9.9A (attached).

The outdoor location has a standard readily accessible 2.5mm socket ring off a 32A MCB. Running a new connection to the consumer unit looks very disruptive.
The installer has said that it's against the regs to run the AC off the ring as a spur. Stating that 13A is the maximum single item device and as the device has a 20A fuse this is against the rules. Instead they are proposing 2x external units both under 13A peak instead. This seems somewhat counter-intuitive and wasteful in terms of space / equipment.

I (personally) have the 9kW Daikin installed in my property which the installers ran with 4mm SWA cable, and I've never seen it use more than 2kW! Usually it runs at 400W - 800W.

Do the rules specifically prohibit running a >13A appliance off a 32A ring - even if the data sheet suggests it won't exceed 10A?

Many thanks,
James

 

[Sharpend]

It is a regulation recommendation that any electrical device greater than 2kw is connected via its own circuit.

Whilst the item may run at lower than this there are times that it would run at or near too it’s max.

 

[jimmybb]

It is a regulation recommendation that any electrical device greater than 2kw is connected via its own circuit.

Whilst the item may run at lower than this there are times that it would run at or near too it’s max.

Thanks, given the Daikin design manual says peak current for this config is <10Amp, would it be acceptable to put it behind a 13A fused spur, and if there are issues down the line then seek to create a dedicated 20A circuit?

 

[jimmybb]

And more specifically is there a rule that says this must not be done, or is it left up to electrician engineering judgement?

 

[Sharpend]

I personally wouldn’t entertain putting it on a ring circuit but I dare say some do.

 

[MikeJhn]

It is a regulation recommendation that any electrical device greater than 2kw is connected via its own circuit.

Whilst the item may run at lower than this there are times that it would run at or near too it’s max.

Need to qualify that as if hard wired, any over 2kw (Kettle) can be plugged into a ring main.

 

[Murdoch]

Need to qualify that as if hard wired, any over 2kw (Kettle) can be plugged into a ring main.

It’s advised in the expensive books

Kettle’s are used occasionally, air con could run for hours

 

[johnb2713]

It’s advised in the expensive books

Kettle’s are used occasionally, air con could run for hours

Fan Heaters, Tumble driers, oil filled rads ?

 

[Murdoch]

Fan Heaters, Tumble driers, oil filled rads ?

Fan heaters not left on for hours and often 1kw

Tumble dryers aren’t in full power all the time

Oil filled reads are not on for hours and often switch on and off

 

[johnb2713]

Fan heaters not left on for hours and often 1kw

Tumble dryers aren’t in full power all the time

Oil filled reads are not on for hours and often switch on and off

The above assumptions also apply to AC, it's not on taking full load for hours, it doesnt take full power all of the time, it switches on and off. Cheap fan heater as you say are often 1kW or less, good ones are typically 3kW.

My 5.5kW AC unit in my office is currently taking 525w continuously having got down to temperature, it was taking 1900w for 7 minutes to get down to temp.

 

[jimmybb]

And to add to this, this is my 9kW AC yesterday - it spent the whole day significantly below 1kW

 

[jimmybb]

If Daikin’s design document says it uses <10A peak, and 5A median. Then a 13A spur off the ring is within the regs, right?

 

[Murdoch]

If Daikin’s design document says it uses <10A peak, and 5A median. Then a 13A spur off the ring is within the regs, right?

What do the MIs say

 

[binky]

The installer has said that it's against the regs to run the AC off the ring as a spur. Stating that 13A is the maximum single item

Well, if you look in the regs books and the pretty pictures of spurs off rings they show a single double socket, and double sockets are rated at 20A.

 

[jimmybb]

What do the MIs say

Apologies don’t know what a MIs are?

 

[Andy™]

Apologies don’t know what a MIs are?

manufacturers instructions

 

[jimmybb]

The MI shows a 20A fuse in the circuit diagram. The model specs also list currents with Minimum Circuit Ampere at 15.8A. But starting and running current of ~4.5-6A

 

[jimmybb]

Well, if you look in the regs books and the pretty pictures of spurs off rings they show a single double socket, and double sockets are rated at 20A.

Thanks - will try to find this

 

[Andy™]

The MI shows a 20A fuse in the circuit diagram. The model specs also list currents with Minimum Circuit Ampere at 15.8A. But starting and running current of ~4.5-6A
View attachment 15618

if MI's require minimum of 15.8a then it'll need its own circuit. would it work on a 13a spur? probably. would it be compliant? no

 

[jimmybb]

Ok thanks. FWIW I think binky's point is right, the spur current (and fuse) can be up to 20A particularly if the appliance isn't expected to use this much current for long periods.