Building Construction, Renovation, Maintenance & Advice

Safe Electrical Circuits

Electrons, those elusive little blighters manufactured in Surabaya by hard working artisans who rub dead cats on pieces of amber, love copper. They love copper more than aliens like teasing Americans in their UFOs. They like copper even more than little boys like picking excrement out of their nasal passages.

You see, electrons like speed and copper is soft and slippery and they can travel quite fast, anything up to 300,000 kilometres a second, that’s pretty quick really, nearly as fast as a banker closing his wallet.

Electrons are dangerous - they like human bodies

But electrons also like flesh and getting into people’s nerves. We all have our own domesticated electrons that live in our brains. Our mind comes up with an idea and gives an instruction. “Go down to my right hand and tell it to scratch that itch in my bum will you”. “Certainly sir” says the obedient little electron and off it goes running down a nerve to find your right hand.

All these bits of our body are just lumps of flesh and bone and if you think about it, apart from feeding lions, pretty useless without a bit of guidance from our brains. The heart, for example, might be warm and fuzzy and full of all that romance stuff but it does need regular attention. Every now and again our brain calls an electron,

“Go and tell the heart to pump.”
“Certainly sir” says the electron and off it goes.
“Go and tell the heart to pump.”
“What again? Oh alright.”
“Go and tell the heart to pump.”
“I’ve just come back from there.”
“Go and tell the heart to pump.”
“Not again, this is starting to get a bit tedious.”

And so it goes on ad nauseum unless some wayward electron on a trip from Surabaya comes along and confuses the issue.

“Where are you going?”
“I’m off to tell the heart to pump.”
“To tell the heart to pump, why?”
“Because the brain told me to.”
“What, you let a brain tell you what to do? Come with me, I’m going to see the earth.”
“The earth? That sounds far more interesting.”

It’s a very good idea to keep feral electrons away from our brains, lungs and hearts if we can.

Electrons don’t like anything to stand in their way and, while the likes of Lance Armstrong can always “boost their performance” when faced with a strong headwind, the poor little electron is easily slowed down by a bit of resistance. They can get a bit hot under the collar and many a house has burned down due to some pissed off electrons meeting resistance while trying to escape.

Electrical Safety in the home

The most dangerous things in our houses are earthquakes, fires, electric shocks and, of course, leaving the toilet seat up. Earthquakes don’t happen very often, thank goodness, fires and electric shocks are usually caused by wayward electrons and toilet seats being left up are usually caused by being male.

So what can we do to protect ourselves.

In the case of Earthquakes we can make sure the structure of our houses are properly designed and built, a topic we have covered in other dusty annals of Fixed Abode.

In the case of wayward electrons we can make sure that our electrical installations are safe. If they are properly designed and installed they will have safety mechanisms built into them that will cut off the supply of power if there is a problem.

It is most important to make sure the wiring in our houses is correctly installed, not an easy thing to achieve in a land where parking a car is a highly technical skill requiring exceptionally talented people to advise and guide you with those essential words “terus, terus”.

Standard Electrical Cable

Standard electrical cable used for house wiring in Indonesia is NYY and NYM cable, these are recognised international world standard cables. NYM is designed for internal use, it should not be used in places exposed to direct sunlight or outdoors. NYY is a heavier duty cable that can be used outdoors, embedded in concrete, in water or buried in the earth but should not be used where mechanical damage is to be expected. (It is advised that all electrical cable is installed in rigid plastic pipe known as conduit).

These cables come in two and three core versions, the “cores” are copper wires wrapped in coloured insulating PVC sheathes and all enclosed in an outer sheath. There are different thicknesses of copper wire used depending on the amount of electricity being carried, for normal household installations we use cable with copper cores with a cross sectional area of 2.5 square millimetres.

Two core cable (NYY-O and NYM-O) is used for lighting circuits where no earth is required and has two wires: a brown one which is the live wire and a blue one which is neutral.

Three core cable (NYY-J and NYM-J) is used for plug sockets and any other circuits that require earthing. This cable has a brown wire for the live, a blue wire for the neutral and a third wire which is yellow and green striped and is for the earth.

The best quality of cable is generally regarded to be “Supreme”, you will find the name is printed in black friendly letters along the cable. Next best is “Focus“, lower quality cable is Eterna and Extrana and then you get into the “also rans” with names such as Dot Chi Cables or the Sum Ting Wong Company which are really useful cables for strapping 5 sacks of rice, 14 cans of paint and a 3 piece suite onto the back of your motorcycle or, for that matter, fastening toilet seats down.

It is wise to take note that the price of cable reflects its quality and the average electrical installation contractor is alway keen to save a few shekels regardless of how much it lowers the level of safety.

For safety reasons power circuits need 3 core cable

Along with reinforced concrete structures the electrical installation is the part of building construction that you should never skimp on. You would be amazed (well probably you wouldn’t) at how the safety of a valuable property is seriously compromised by some grubby contractor wanting to save a mere Rp50,000.

I was once asked to investigate a case where a little girl nearly died having been electrocuted in a major public facility. It turned out that the contractor had saved a bit of money by installing two core cable instead of three core cable for the plug sockets. The neutral (blue) wire had been connected as both the neutral and the earth. One day there was a fault in a lighting system that had been plugged into an offending plug socket, a steel marquee frame became live and a 3 year old girl nearly died.

Electrical circuits are tested with a continuity tester

So how do we know if our electrical installations are safe and that Joe the former bakso roller hasn’t put a nail through the cable somewhere or the rats haven’t had a banquet on our multicoloured PVC without having to go crawling around in the roofspace on a mission rather like trying find a set of false teeth in a snowdrift?

We can test a wiring installation by means of a continuity test. For this we use a continuity tester, a meter that sends a pulse of high voltage into the cable and measures how much leakage there is. We measure the resistance between the different cores in the cable. The test tells us if there are any short circuits, if the PVC insulation is working correctly and if the joints in the cable are properly connected. We don’t want those mischievous little electrons escaping where they can do harm (such as burning your house down or stopping your heart), so we want a high electrical resistance, anything up to 2,000 megohms (that’s a lot of ohms).

Granny is startled, she has stopped knitting,

“Resistance is useless” she grunts.
“No granny, electrical resistance, we are talking about ohms.”
“Ohms, what on earth are those?”
“An ohm is a unit of measurement of how much something resists the flow of electricity, it is named after German Georg Simon Ohm.”
“I am sure that someone, somewhere will find that really interesting.”

Continuity testing ensures electrical wiring is safe

Unfortunately in Indonesia many electrical circuits fail continuity tests. There are two basic reasons for this. The first is the quality of the cable used, poor quality cable leaks electricity.

The second is the standard of the installation particularly the wiring connections. If you watch the average bakso roller who learned his electrical skills under the the watchful eye of his uncle, a highly regarded collector of cigarette butts, you will note that to connect cables he will bare the ends of the copper wires, twist them together then wrap a bit of plastic tape around the join. This is the standard method used but is not good enough.

Cable connections should use a small plastic cap which is screwed down onto the two copper ends. The plastic cap does two things: firstly it holds the two twisted copper ends tightly together and secondly it covers the joint to insulate it. The whole joint should then be contained inside a junction box.

Next time you are in someone’s fancy private villa have a look around the ceiling edges. You might see electrical cables joined together with bits of plastic insulation tape covering twisted copper connections, all too often these dodgy connections are pushed up under an alang alang roof. Perhaps you could ask your host if he/she is insured against fire.

In the case of the toilet seat you could consider protecting yourself by sex change surgery, taking the hormones or, probably more effectively, removing the offending seat altogether, there’s nothing like a dose of cold ceramic on bare cheeks first thing in the morning to bring things back into perspective.

Copyright © Phil Wilson 2013
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

8 February 2017 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali 80228, Indonesia
Telephone: +62-361-288-789, Fax:+62-361-284-180