What is a Shelly Bypass Used For And Why Do I Need One?

11 Jan 2021

With the recent introduction of the Shelly 1L to the Shelly Home Automation range, you may have noticed an add-on which is available specifically with the Shelly 1L called a Shelly Bypass. We sell the Shelly Bypass in the store as a standalone product or as an add-on with any Shelly 1L or Shelly Dimmer 2 devices, but what actually are they and do you need one?

The great thing with both the Shelly 1L and Shelly Dimmer 2 is they work without the need of a neutral line. That’s great news for us here in the UK if you are wanting to add a Shelly device behind a light switch, where typically we do not have a neutral wire.

What is a Shelly Bypass?

Shelly Bypass is required where there is neutral wire and where the power consumption is less than 20 watts. If the load of the light is very low (typically, LED lights), you need to add some form of load, that's where the need of a bypass comes in!

Rather than turning off the light, the Shelly 1L and Shelly Dimmer 2, dim the light so low, it stops glowing, leaving a very small current flowing through the circuit of the Shelly Device to keep it running, even when the light is off.

Do I need a Shelly Bypass

Most LED lightbulbs in the UK are under 20 watts.

If you are using the Shelly 1L or the Shelly Dimmer 2 in a place with no neutral wire (such as behind a light switch) and you live in the UK, yes you most likely do.

Where do I install the Shelly Bypass

If you are installing a Shelly Bypass in a lighting circuit in the UK, you will need to attach the Shelly Bypass between the Output wire going to the lightbulb and the neutral going to the other side of the lightbulb. It will feel very unnatural to connect the wire this way. Most people in the UK have a ceiling rose or light fitting which allows the space for a Shelly Bypass. They are really small, being only 39 mm x 23 mm x 7 mm.

Do I need a Shelly Bypass if I have a Neutral Wire?

No, you only need a Shelly Bypass where there is no Neutral wire.

If you have a Neutral wire you may wish to consider either the Shelly 1 or the Shelly 1PM unless you need the dimming function specifically.

If you are unsure which Shelly Device is best for your circumstances, please reach out to our team who will be happy to discuss your options with you.

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