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  • Writer's pictureRJA Electrical Services

Hot tub electrical installation guidelines

Updated: Dec 27, 2020

The Government introduced a law in January 2005 which demands that most electrical work in UK households is only carried out by a ‘competent person’. The law means that Electrical safety requirements have been included in a new Part P of the Building Regulations. Hot tub installations must also comply with section 702 in the 17th Edition IEE (Institute of Electrical Engineers) Regulations as they fall in the same category as swimming pools.

This guide sets out everything you need to know for setting up an electrical connection for a hot tub including details on Part P and how to find a qualified electrician.

  1. What is Part P?

  2. Who is responsible for ensuring electrical work meets Part P requirements?

  3. How do I ensure Part P requirements are met?

  4. How many amps do you need for a hot tub?

  5. What are the electrical requirements for a hot tub?

Electrical installation

How many amps do you need for a hot tub?

Most hot tubs require at least a 13AMP supply with larger hot tubs requiring a 32AMP supply. We can liaise with your electrical contractor regarding the exact specification for your Hot Tub, alternatively more details can be found within the technical specifications on our hot tubs pages.

13 AMP electrical requirements

The electrical requirements for the 13AMP plug-and-play Hot Tubs are the simplest to complete. The 13AMP Hot Tubs simply plug into a standard domestic power supply so all you need for the 13AMP Hot Tubs is an outdoor waterproof plug socket with RCD protection. We will provide up to 5 metres of cable and a plug to plug into the socket you have provided.

32 & 40 AMP electrical requirements

For a 32AMP hot tub, 6mm² 3-core SWA cable is needed and a 10mm² 3-core SWA cable is perfectly suitable for a 40AMP Hot Tub.

An IP65 45AMP Rotary Isolator Switch is also recommended so that the hot tub can be isolated outdoors in an emergency or for service work. This is simply a rotary on/off switch but should be sited more than 2 metres away from the hot tub so that bathers cannot be in the hot tub whilst touching the switch.

The electrician should fit a suitable weather proof block connector to the end of the tail from the isolator, the hot tub supply can then be directly hard wired into the weatherproof block connector inside the hot tub. Waterproof gland packs should be used to prevent ingress of water on all electrical connections (2 at the isolation switch). Ensure that all earth cables are clearly colour coded with green/yellow insulating tape or earth sleeve.

What are the electrical requirements for a hot tub?

The electrical installation must comply with BS:7671 – “Requirements for Electrical Installations IET Wiring Regulations”, particularly concerning the following specifications:

  1. The hot tub must be hard wired on its own fused spur back to your household consumer unit, not sharing a supply with any other appliances

  2. The hot tub should be protected by a sufficiently rated MCB (mains circuit breaker) and should cover the maximum amperage pull of the Spa plus 25% to allow for brake torque (i.e. the extra rush of current when pumps are first started). Therefore, a hot tub that has a maximum current draw of 20 amps should be fitted with a 25AMP MCB

  3. The hot tub should be protected against earth faults by an RCD (Residual Current Device). This is a trip switch which prevents the possibility of an electric shock from damaged or waterlogged cables and connections. A suitable rated 30mA RCD is recommended

  4. Outdoor cabling should be protected from damage by either laying protective ducting (pc pipe) below ground or by using Steel Wired Armoured (SWA) cable. Your electrician will calculate the size of cable required depending on the loading and the distance from the mains supply

Once the hot tub is filled with water and the electrical supply is installed your installation team should commission the hot tub and check that everything is fully operational before handing over to you with a complete chemical training guide and hot tub features.

If you are in any doubt about the required electrical guidelines you should seek professional advice from a fully qualified electrician.

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