Wiring a 1KW pool heat pump

[TheGC2020]

Hello. I was hoping someone could please help me with some queries?

I’ve just taken delivery of a single phase pool heat pump rated 1kw, with running amps of 4.5. Retailer has advised that it should be wired into a separate type C MCB with a min 10A fuse. I was hoping I could just put a standard 13A plug on it (perhaps with a 10A fuse) and plug it into an IP66 socket (either an RCD socket or with the socket on an RCD protected circuit) on a 2.5mm arctic blue type flex. Existing circuits are B curve type and rated 32A. Am I being naive, what am I missing?

The heat pump is to heat a temporary/semi permanent above ground pool and will also have a feed for a pump which should require no more than 500W. Not sure if the retailer is just taking a belt and braces approach as many of their other heat pumps are more powerful.

Your thoughts please? Thank you

 

[marconi]

Sir/Madam, this is a job for a qualified electrician who understands the risk factors, the UK regulations and how to design and install something safe and durable. He/she will (if not don't pay) inspect and test afterwards and provide you with a valuable certificate which is a very handy thing to keep safe somewhere, just in case.

 

[TheGC2020]

Sir, this is a job for a qualified electrician who understands the risk factors, the UK regulations and how to design and install something safe and durable. He/she will (if not don't pay) inspect and test afterwards and provide you with a valuable certificate which is a very handy thing to keep safe somewhere, just in case.

Many thanks for the advice - that’s where I was coming to in my mind too. I know that there are special regs for pools and extra risks. Purely to satisfy my curiosity - do you know why a 1kw electrical device can’t go on a plug?

 

[marconi]

My competent EF colleagues will answer your question.

 

[westward10]

The manufacturer is suggesting the protective device at the consumer unit but there is no reason why it cannot be connected through a suitable 13A socket from a dedicated circuit or otherwise.

 

[TheGC2020]

The manufacturer is suggesting the protective device at the consumer unit but there is no reason why it cannot be connected through a suitable 13A socket from a dedicated circuit or otherwise.

Many thanks - good to know my basic understanding was correct re the plug. Does ‘or otherwise’ mean there might be another option than running a new dedicated circuit from the CU as that’ll be a pita?

 

[Lucien Nunes]

A heat pump has a compressor with a high starting current, typically 5x the running current if it is not inverter driven. They may have experienced problems with 13A plug fuses blowing, hence the suggestion to use a C-type MCB which is less likely to trip on the starting current. Since the higher instantaneous trip level requires a lower loop impedance on the circuit to maintain safety, they probably recommend a 10A MCB as the lowest they have found compatible with the compressor, to avoid onerous cable size requirements.

Note also that a device with high earth leakage current (>3.5mA) should not be connected via a 13A plug and socket; a more robust connector or hard-wiring is required to absolutely minimise the risk of the earth becoming disconnected. It is unlikely that this unit has such a high leakage current but that is another reason a 13A plug might be unsuitable for a specific application <13A.

 

[TheGC2020]

A heat pump has a compressor with a high starting current, typically 5x the running current if it is not inverter driven. They may have experienced problems with 13A plug fuses blowing, hence the suggestion to use a C-type MCB which is less likely to trip on the starting current. Since the higher instantaneous trip level requires a lower loop impedance on the circuit to maintain safety, they probably recommend a 10A MCB as the lowest they have found compatible with the compressor, to avoid onerous cable size requirements.

Note also that a device with high earth leakage current (>3.5mA) should not be connected via a 13A plug and socket; a more robust connector or hard-wiring is required to absolutely minimise the risk of the earth becoming disconnected. It is unlikely that this unit has such a high leakage current but that is another reason a 13A plug might be unsuitable for a specific application <13A.

Ahhh making a lot more sense and good
to understand the reasoning - many thanks for taking the time for the informative response