The Robotic Lawn Mower Perimeter Wire Revisited...

Fitting a perimeter wire often requires breaking and re-connecting individual cables together; and when you buy a robotic lawn mower, they come with a selection of appropriate connectors. These, however, are quickly used up, and especially if the wire breaks (which it will do), leading to a hunt for replacement connectors.

Perimeter Wire & Guide Wire Breakage

For robot mowers that use perimeter wires, there are usually two ways that the wires are used:

• as a boundary for the work area;
• to guide the mower to the charging unit.

While any wire break is irritating, breaks in the boundary wire present more of a headache than the guide wire, as it involves investigating the whole loop. The instructions for the Gardena 40Li / Flymo 1200R show that there are three connection points on the base: two for the boundary wire and one for the guide wire.

There's also a light on the base (where the mower 'docks' -- you need to take it out to see the light) which has several states. States related to the boundary and guide wires are:

• Green -- all okay;
• Blue flashing -- break in the boundary wire;
• Yellow flashing -- break in the guide wire.

Fixing the guide wire is easy enough, as you can trace it fairly easily (I made a plan of my own installation!), and splice the wires together.

Splice Clips

To do this, I use a splice clip, pictured here on the right, which costs about 2.5 EUR for 20 (less than 4 GBP) delivered, from online retailer Banggood.

These might not be water protected like the 3M ones that came with my Gardena 40Li, but they do the job adequately, and are a lot better than the 'sugar cube' type blocks that I was using previously, which tended to rust.

These clips can also be used to repair the boundary wire, once you know where the break is!

The instructions for doing this can be a bit confusing, but the diagrams in the user guide are pretty self-explanatory. However, since they require plugging a flying wire into the base unit, and then using it to test ever-increasing sections of the perimeter wire, I found using a terminal and spade connector made things easier.

I found these on Banggood at the same time as the splice clips (click here), for less than £2 per pack of 5. One of the 'spades'can be attached to the end of the flying wire, of which the other end is plugged into the base, in place of the regular other end of the boundary wire.

Terminal/Spade Crimp Clips

The t-connection bits end up on the boundary wire -- there being no way to take them off -- but are useful each time there's an issue.

As long as you remember (or write down) where they are, you can troubleshoot that much more easily, as well as 'shorting' between two points if you want to limit your robotic mower for some reason.

To do that, all you need is a bit of wire, the right length, with a spade at each end, and two points on the perimeter wire with a t-connector between which to put the flying wire. Now, when the mower approaches it, it will treat the new wire as if it is the boundary wire.

Simple!