This article from the experts at NICEIC looks at the installation of wireless smart devices and aims to provide guidance to the contractor when installing such types of devices.
Many new installations include the provision for smart control, typically installed during the initial construction, based on a system-Bus type configuration using multi-pair or data networking cables. However, increasingly, home owners are requesting the retrofitting of wireless smart devices within older properties as a means of providing smarter and more convenient control of lighting, heating and security monitoring.
Regulation 537.3.1.3 of BS 7671 permits the use of functional switching, including smart devices, which interrupts the current using semiconductors. Typical devices consist of an in-line module placed in the circuit between the supply and the equipment to be controlled; for example, between the switch and a group of luminaires. Most offer the facility for dimming and integrate timing functions; additionally, with the option of changing the colour rendering index (CRI) of the light output, depending upon the type of luminaire installed. Having such functionality provides the means to set up lighting scene scheduling usually through an app with a tablet, phone or other hand-held device. Other devices such as an in-line relay controller, typically rated up to 16 A, are capable of switching larger current loads, usually associated with a radial circuit, with some offering the facility for live energy monitoring.
Many manufacturers are now incorporating smart control features within their products; for example, within external passive infra-red (PIR) detectors, LED flood lighting, various lamp types and smoke/heat detectors.
However, with so many smart devices available having varying operational characteristics and setup configurations, this could lead to issues with compatibility when attempting to synchronise and operate multiple devices in the home, consequently affecting the ability of low voltage circuits to operate as intended (Regulation 512.1.5). To minimise the risk of this happening, manufacturers’ instructions for compatibility should always be carefully considered at the design stage.
Accessibility
Smart devices used to control luminaires are often small and designed to fit within a confined space, such as within switch boxes or in a ceiling space adjacent to the luminaire. However, when installing such devices remote to the item of equipment to be controlled, only those devices which are indicated as suitable for their installed location according to the relevant product standard, as shown in Table 55.3 of BS 7671 should be used (Regulation 559.6). Provision of suitable access arrangements to facilitate subsequent inspections and maintenance must be provided (Regulation 513.1). Where it may be difficult to identify the purpose of switching devices or control gear used for smart control a suitable means of identification shall be provided (Regulation 514.9.1 (iii)). Recording the location of such devices used within the installation on a certificate or accompanying drawings may be appropriate.
Control
Many low energy networks require a coordinator device, typically a hub or a controller usually connected directly to the router and Local Area Network (LAN), as shown in Fig 2. The hub is the root of the network providing a communication link between paired ZigBee, Z-Wave and other similar types of smart devices; and is usually the first component to be set-up during the initial installation of a smart home prior to connecting other devices. The hub holds data relating to the LAN, such as its IP address, which provides the gateway for granting access to the hub’s network while remote from the home. The hub also provides a security centre for the connected smart devices. Some manufacturers producing equipment with inbuilt ZigBee and Z-Wave protocols are starting to introduce controller hubs allowing communication across multiple platforms from different manufacturers.
As an example of the type of control available, the activation of an external PIR flood light integrated with Z-Wave communication may instigate a direct signal back to the hub (if in range), or through other connected smart devices on the network prior to reaching the hub. This may then enable designated lighting within the house to switch on and, in addition, send a notification to a phone alerting the user that an activation has been detected.
Summary
The use of smart devices within older properties is becoming a popular choice with home owners as a means to achieve greater control for energy efficiency and improved security. However, with so many products available great care must be taken when selecting smart devices for a particular project. The risk associated with compatibility between devices from different manufacturers and that of other equipment used around the home may impact on the reliability of low voltage circuits to operate as intended. To mitigate any risk manufacturers’ instructions for compatibility should always be considered.
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