LightwaveRF LW821 In Line Relay

Price match guranteePrice match guarantee

We can price match this item if found elsewhere. Call us on:

0333 400 9500

Quoting product code: N64LL


Our delivery options

Free standard delivery (orders over £10)
3-5 working days 9am-5pm
Standard delivery (orders under £10)
3-5 working days 9am-5pm
Next day delivery
Mon - Fri, order by 6pm
From £5.99
Specific day/time delivery
Choose am / pm OR before 9am / 10.30am
From £5.99

Specific options for this product are available in the checkout. Read more delivery information

About this product


  • Fully remote controllable inline relay
  • Works as part of the LightwaveRF home automation system
  • Compatible with Amazon Echo and Google Play

Product overview

• Fully remote controllable inline relay
• Works as part of the LightwaveRF home automation system
• Compatible with Amazon Echo and Google Play
• Requires optional LightwaveRF WiFi Link to use the app
• Ideal to convert existing lighting equipment to be remote controllable
• Switches up to 500W
• Control via your Smartphone* or the web wherever you are
• Simple in-line installation

What can I use this relay for?
This relay is designed to convert your existing lighting equipment so you can use a remote control or even your smartphone or tablet to switch the lights on or off or even drawing the curtains when attached to a motor. This can improve security in your house with the simple act of turning the lights on and closing the curtains while you are away from the house at night, potentially scaring off intruders.

How easy is the relay to install?
Wiring this relay can be as easy as wiring a plug. On the bottom of the relay is a hatch which, when opened, allows you access to the terminal screws. Once you have opened this hatch wire the live, neutral and earth to the relevant terminals. If you are in any doubt, we recommend you consult a trained electrician, who will be able to wire this in.

Please note: To use the app with this product, you will require the optional LightwaveRF Wi-Fi Link A23RX.

Rated 4 out of 5 by from Does pretty much what it says on the tin This was the 3rd one of these i'd bought for switching outside lights remotely. I originally wanted to switch between PIR supply and permanent feed. I.e. attaching the load (lights) to the Common but after trying it and some contact with Lightwaverf tech support found that this item does not work like a simple relay in this respect so I had to add an additional mains relay with this item switching the coil supply to achieve what I wanted. Seem reliable, apart from above my only niggle is that you have to get close to live connections to press the pairing button when ideally I want it safely in an enclosure before I turn the juice on.
Date published: 2016-12-03
Rated 5 out of 5 by from Wanted one to automate my outdoor light, so I could wire it in parallel with an existing architrave switch in the event we needed it to hand when we came in the door. Tiny little device that actually has SPDT contacts with a center off. Well worth it if you're looking to automate your lights or control them remotely.
Date published: 2014-11-11
Rated 4 out of 5 by from Very good device, but questions over reliability Good little device for controlling all sorts of electrical devices. I use it for controlling a zone valve on my central heating system. However, this device was to replace a previous one that had failed after a three or four years
Date published: 2017-02-19
  • y_2018, m_3, d_16, h_4
  • bvseo_bulk, prod_bvrr, vn_bulk_2.0.7
  • cp_1, bvpage1
  • co_hasreviews, tv_0, tr_3
  • loc_en_GB, sid_N64LL, prod, sort_[SortEntry(order=RELEVANCE, direction=DESCENDING)]
  • clientName_maplin-en_gb


Power Source
Voltage AC 230 V
Maximum Current Nothing specified
Wireless Yes
Expandable Yes - LightwaveRF Products
Push notifications No
Wi-Fi No
Bluetooth No
Compatible with Standard Wi-Fi Routers No
Remote Controlled via App Yes
Remote Controlled via Webpage No
Operating Systems and Protocols
iOS iOS 6.0 or higher
Android Android 2.3 or higher
App Compatibility Free LightwaveRF App
Requires Computer Software No
Dimensions 68 mm x 28 mm x 52 mm
Indoor Use Yes
Outdoor Use No
Cable Length N/A – No Cable
Package contents
In Line Relay

Hi What frequency does the lightwave rf in line relay work off we are trying to control a complete room system with tvs and blinds using a logitec programmable remote

Asked by: Londons Electrician
433.9Mhz is the operating frequency of the remote designed to be paired too this.
Answered by: Billy
Date published: 2018-01-28

Will this work with 3 x 5 watt led dimmable down lighters?

Asked by: Woodey 99
Unit is rated up to 500w max load
Answered by: Les
Date published: 2017-10-20

Is it possible to pair this with a LW205WH switch without also purchasing a WiFi Link?

Asked by: beejay
Yes, I am pleased to advise the item will support this use.
Answered by: Dominic
Date published: 2017-02-07

do you know if i can run it as a 12volt switch . thanks

Asked by: tboneukuk5
We would be unable to advise on specific usage. As indicated by the provided documentation The unit has a max load of 500W, if you unsure as to usage we would advise contacting a qualified electrician for advice.
Answered by: Les
Date published: 2017-01-04

Can i use this to power all the ceiling lights in my house? at the moment, i only have two lights that are dimmable connections. Also, how many would i need for all the lights in a typical 4 bedroom house?

Asked by: Pritesh
This service is for frequently asked questions and does not allow two way communication, In order for us to best assist you with your technical issue please contact us on the details below: 0333 400 9500 or email
Answered by: Billy
Date published: 2016-09-28

can the outputs be set to give a single pulse rather than being switched on or off? I can't find the answer in the manual.

Asked by: Thomas
This is only designed to switch between two connections, either as an on/off relay or to switch between two separate circuits. It is not designed to output a pulse I'm afraid.
Answered by: Gareth
Date published: 2016-07-12

Is there a minimum load for this relay to operate correctly? I wish to simply use it to swith a 10 watt LED light on and off remotely. (The 1 gang dimmer does not work with it)

Asked by: Anonymous
This information is best detailed in the user manual / datasheet which is available from the download tab on the products webpage, if you do need any in-depth Technical support please feel free to give us a call on 0333 400 9500 or email us on
Answered by: Dominic
Date published: 2016-06-30

Once paired this unit will be sealed in a wooden housing. Periodically mains supply will be off completeley, once restored will the pairing still be active or would the unit need to paired again? Will the transmitter work through wood?

Asked by: Zeroblue
Sorry but the user guide offers no advice regarding usage in such conditions. The relay will transmit through wood although it's range would be reduced. The relay will remember pairing but no indication is give for how long if devoid of power. I'm afraid such a question would need to be fielded by the manufacturer themselves Luckily Megaman / Lightwave have a web portal designed for exactly this kind of question. I included a link below.
Answered by: Les
Date published: 2016-05-18
  • y_2018, m_3, d_16, h_4CST
  • bvseo_bulk, prod_bvqa, vn_bulk_2.0.7
  • cp_1, bvpage1
  • co_hasquestionsanswers, tq_18
  • loc_en_GB, sid_N64LL, prod, sort_[SortEntry(order=LAST_APPROVED_ANSWER_SUBMISSION_TIME, direction=DESCENDING)]
  • clientName_maplin-en_gb