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230V Radio-Interlinked Relay Base for Carbon Monoxide Alarms EI261 and EI261D - Ei420

In Stock
£51.59 inc VAT
(£42.99 ex VAT)
The Ei420 is a mains powered relay base with built-in lithium battery. The base is suitable for interconnecting carbon monoxide alarms into a radio-interlinked system.
  • Rechargeable 10 year lithium battery back-up
  • 5 year warranty
  • Hard-wire up to 12 EI261 alarms 
  • RF performance to EN 300220-3
  • EMC performance to EN 301489-3
  • Cover to allow remote siting 
  • Visual RF transmission indicator
  • RF frequency: 868Hz band 
  • Low battery indicator
  • Hard-wired input to connect Ei261 CO alarms to any Ei radio-interlinked system
  • Can be used as a stand alone repeater unit for Ei RadioLINK alarms and bases
  • RF range 150 metres (minimum) in free space and up to 30 metres in buildings
  • Digitally coded to avoid interference with neighbouring systems
  • Two way signaling (The unit will transmit a hard-wired signal upon detection of a radio signal and a radio signal upon detection of a hard-wired signal)

This is the technical data for the 230V Radio-Interlinked Relay Base for Carbon Monoxide Alarms EI261 and EI261D - Ei420.

Product Code EI420
Weight 0.18kg
Dimensions (HxDia) 26x140mm
Back-Up Battery Longlife Lithium Battery
Sound Output 85dB
Temperature Range 0 to 40°C
Humidity Range 15% to 95% Relative Humidity

Technical Data Sheets

The following technical data sheets are available for this product:

CO Alarm Interface

If purchasing the Ei420 as a RadioLINK interface with a CO alarm then it should be mounted close to the alarm. It can be mounted a short distance away or directly above the alarm. Choose a suitable mounting position near the mains supply but keep the Ei420 away from metal surfaces or large metal objects (e.g. water cylinder, fuse boards) which can reduce the RF signal range.

Repeater Interface

The function of a repeater is to receive and then re-transmit the RF signals. This shortens signal paths throughout the installation to give improved RF signal reliability. If purchasing the Ei420 for use as a repeater it should be mounted in an intermediate position where the RadioLINK signal needs to be strengthened.


  • Disconnect the AC mains supply from the circuit that is going to be used. Where the incoming wiring is on the surface of the wall/ceiling, the appropriately sized trunking / conduit must be chosen to mate with the unit. There is one suitable surface cabling knockout. and one rear entry knockout.
  • Unscrew the cover attachment. Use a sharp knife to remove the material from the knockout, making sure that there is no gap when mated with trunking/conduit.
  • Screw the Ei420 to the wall or ceiling after first removing the required knockout and bringing the house wires through it.
  • Connect the wires to the appropriate terminals.
  • Activate the rechargeable cells by carefully and gently sliding the switch to the “on” position
  • Fit and screw the cover to the Ei420 using the two screws supplied.
  • Connect the mains power to the Ei420 module. Check the green light is on. If the green light changes to red every 10 seconds then switch off the mains power, remove the cover
    and check that the battery slide switch is in the “on” position. Replace the cover and turn the mains power back on. If there is still a problem the rechargeable cells maybe depleted. Leave the unit on mains power for 2 hours to charge and check that the green light is now on continuously.
  • Press and hold the House Code switch through the hole in the cover using a small screwdriver, (see Figure 3) until the green light changes to red. Immediately release the switch and the light will flash red quickly. The green light will then flash red every 5 seconds (this is a dual colour light so the green light remains on when the red light is off and vice versa). Similarly, put all of the other RadioLINK units in the property into House Code Mode (see relevant user instructions) within 15 minutes (before the House Code timeout period expires).
  • Check that all of the RadioLINK units communicate with each other by counting the number of times the light flashes on each unit in turn.
  • All of the units will automatically exit the House Code Mode after 30 minutes. However, we recommend that you manually exit the House Code Mode by pressing and holding the House Code switch on until the House Code light remains on. Immediately release the House Code switch. The light should stop flashing and an “Exit House Code” signal will be sent to all other Ei168RC and Ei420 units in the system.

For detailed installation instructions please refrer to the User manual


Q. Where more than one radio-interlinked battery operated smoke alarm is installed, if the battery in one alarm failed would the other alarms be affected?

A. If one alarm was to malfunction the other units would not be affected, if it was due to alarm failure. If the fault was with the radio-interlinking signal, then all alarms that are in the chain after the faulty alarm would be affected and they would not go off.

Q. Are there any restrictions to the distance a radio-interlinked smoke alarm will work?

A. Most radio-interlinked alarms have a range of 150 meters in an open space and up to 30 meters in buildings. The thickness of the walls and partitions will affect the travel distance of the signal.

Pricing & Availability

Model Stock Levels Prices Weight
230V Radio-Interlinked Relay Base for Carbon Monoxide Alarms EI261 and EI261D - Ei420
Product Code: EI420
In Stock

£51.59 inc VAT

(£42.99 ex VAT)


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