Out of Africa - Electrics

One of my tasks whilst visiting J&S in Kenya was to install lighting and a 13A outlet in the new school room. Some allowance had been made during the building work, so there was already a conduit from a 13A socket in the adjacent church to the roof space above the school room.

This post is about what I learnt about Kenyan wiring and some confessions.

The incoming supply is overhead from a roadside pole where only two wires are visible. As far as I could tell, then, the earthing system is 'TT' i.e. the protective earth is supplied by the customer and there is no explicit connection to the supply authority's earth.

I learned that, as a rule, red = Live, black = Neutral, green/yellow = Earth. And that all domestic carcass wiring is done in 20mm black plastic conduit. I say "as a rule" because apparently rules are there only to be broken.

Incoming supply switch-gear

You can click on these images to enlarge them. The picture shows the supply authority's switch-gear which is mounted in a rough metal enclosure on the outside wall of the church. The incoming supply is the black (coaxial?) cable entering at the top and terminates in the DIN-rail double-pole switch at left. This is turn connects to the HXP100DIM metering module via scarily thin wires possible only 2.5 sq.mm. This module has a twin wire data connection to a coin-slot meter inside the church. The supply connects from here to the larger switch on the right where it is joined by an earth cable presumably connected to the customer's earthing rod.

There is a thoroughly normal consumer unit inside the church building with several MCB's which supply lighting and power outlets.

Showing the incoming supply cable in the angled conduit

You'll see that nothing is properly fastened to anything - the supply authority's conduit is roughly supported at a crazy angle only by the geometry of the wall.

Church socket wiring, with my spur connected

Within the church, which is in effect a large single room, there is what I take to be a ring circuit running around the perimeter. It runs in conduit under the plaster but becomes visible at periodic conduit boxes none of which are fitted with lids. For all that effort I could find only two double 13A sockets on this ring, both on the platform. One was hanging (not screwed in). The other (shown above) was properly fastened and was where the provided conduit to the school terminated.  You'll see from this that the colour scheme adopted is:

Green/yellow = Live, green/yellow = Neutral, red = Earth.

In spite of that unfortunate choice the wire gauge appears to be correct i.e. 2.5 sq.mm for Live and Neutral.

My wiring uses the correct Kenyan colours and can be seen connected as a spur in the above picture.  We purchased our wire by the metre at a hardware store in nearby Chavakali.  Here I specified 2.5 for power and 1.5 for lighting, and the store (and I) judged the correct gauge by the larger outer insulator diameter for the supposed 2.5 sq.mm. However when I started working with this wire I found the outer diameter to be a lie, as shown below where I latter compared with wires stripped from Irish 2.5 sq.mm T&E cable.  The bare copper earth wire at top is thus 1.5 sq.mm.

It would appear that the Kenyan green/yellow and black "2.5" is indeed 2.5 sq.mm but the red "2.5" is in fact much less, perhaps 1.5 sq.mm.  And of the two lighting gauge wires at bottom right only the red one is really 1.5, the black being significantly less maybe only 1 sq.mm.

Comparison of wires

Did this matter?  Given the sloppy nature of the wiring generally, our reluctance to go source the correct gauge, and the fact that the two new lights were rated 35W each and that the single double-socket would be used at most only to charge electronic computing equipment, I reckoned not.

According to Irish code an unfused spur from a ring circuit is not allowed, also not allowed is a direct connection from a ring circuit to a reduction in wire gauge for lighting. But I committed both sins, in addition to the wrong wire gauge I had been duped into buying.

But at least all my wiring was in conduit and used the correct colours. Whereas at J&S's house, which had been wired by a "professional" electrician, the conduit stops a few inches short of lighting fixtures so you have single-insulated wire bridging this gap, albeit sometimes wrapped in insulation tape for good measure.

Oh, and when the plumber came to connect a tap to the rainwater tank we had installed, he needed mains power for his electric "welding" machine for PPR water pipe.  An extension cable was not to be had. Indeed his complete tool set consisted only in this rather ancient machine and a couple of plumbing wrenches. We had to supply hack-saw, pipe and fittings, lunch and a drink. So I used some of our recently purchased black lighting wire, connecting into his machine's 13A plug at one end and splicing into the ring main in one of those exposed conduit boxes at the other end, there not being a 13A socket within reach. It did the job, though would hardly have passed health and safety.