Cable routeing

The Bricking It flat needed over 1,000 individual connections, and to achieve this would take planning, accuracy and teamwork.

Electricity is potentially dangerous and safe working practices are essential.

So Sparky Peter Briggs and our trainees had their hands full.

We ask Peter to take us through the key skills involved in the first fix:

Setting out
Before we do anything we need to look at the drawings to check that everything can be done.

Next we need to plan the route of the cables. I often spend up to two hours assessing this. In a two-storey building like the flat we need to run the cables through the ceiling, and up wall cavities.

Safety zones
At this stage the trainees have to get familiar with the safety zone. These are designated areas in the wall where cables can run, like 150mm either side of a corner, and where the ceiling meets the wall.

Getting level
It's important to measure your work according to the 'datum line'. This is a horizontal line throughout the flat one metre above finished floor level, which is usually established at the very beginning of the project. It is made using a laser which spins around on a tripod. The laser projects a mark onto the walls, which is then marked up in pencil. We use this line to make sure all our work is level.

Tubes
In the flat we can't penetrate the brick walls, so we have to fix galvanised tubing, or 'conduits', to the walls and run the cables through them. It essential to use a spirit level to ensure that the conduits go up straight.

Accuracy
Accuracy is very important, and all the sockets and switches need to be straight and level, especially in bathrooms and kitchens where they might be set against tiling. Otherwise the owner's going to notice that the light-switches are different heights, or that the sockets don't line up.

Because we couldn't cut into the original brick walls we had to fix metal surface boxes to take the sockets and switches. It's very difficult to get these straight, as the rough, hard surface sends the drill off course.

It's a good idea to fix the back-box using the slotted holes, rather than the round ones. That way you can make minor corrections. Some of the trainees listened, some didn't.

Stripping
Stripping the sheath from wires is a skill in itself. If you bend it about too much you can weaken it. It can snap off when you try to connect it up.

Checking and testing
Every one of the connections has to be secure, and needs to be checked.

Before plasterers come in to close-up the walls, the system is tested. I did this with David, and surprisingly everything was OK.

Mapping
In theory the plasterers will pull the cables through the plasterboard. In practice one or two are always missed. So we draw diagrams showing exactly where the cables are, so we can find them even if they've been hidden behind the plaster.

At least that's the idea...

The Trainees
Getting the cables into the conduits was painstaking work for some of the trainees. You need two people working together, one pulling and one pushing. Dan and Greg Males ended up pulling skin off each other's knuckles. It's a good example of the importance of working together in a team.

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