You’re working in a temporary classroom block on the edge of the playground and I’ll bet that, even if you’ve got a technician in school, you’ve been told that you can’t be connected to the network because the wireless signal can’t reach you.

We’re all familiar with the poor, disenfranchised classes that inhabit the temporary buildings of our school sites, installed over a hasty summer when a trench was dug to make connections for electricity, water, perhaps even sewage. But there was nobody around to point out that it would be worth burying an ethernet cable under the ground at the same time, and now it’s too late - right?

The network manager might try a wireless system but finds the metal shells of the buildings create a barrier and your class ends up sitting there isolated from the main network and connection to the outside world.

Well, there is a solution, and it’s to deliver the ethernet signal through the electricity supply. You need a competent electrician to confirm that the place where you intend to send the signal from is on the same phase of electricity as the one where you’ll receive it at the terrapins. As long as they match, you’re off.

The best thing is that you can distribute the signal inside the terrapins using a wireless base station, so one connection can feed multiple machines.

We used a product from Corinex called the AV200 Powerline Ethernet Adaptor, which costs pound;128. One box connects between a standard ethernet socket in your main building: this pushes the signal through the electric cabling, and over in your terrapins, another identical box takes the signal out and converts it back to feed through an ethernet cable. You could connect this straight to a single computer or, as we have done, feed it into an AirPort wireless base station and allow as many as 50 computers to share the signal (PCs and Macs can all share the one signal).

We supply two classrooms with five laptops and four desktop computers and, although they are not all are necessarily used at once, we’ve not had any bottlenecks or problems with it.

Then all you’ve got to remember is to invest in security cables and make sure everything is carefully locked down.

Sean O’Sullivan is headteacher at Frank Wise School in Banbury, Oxfordshire.