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Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to "Ask SILICON CHIP" and "Circuit Notebook".

Foil insulation
and CFLs

The whole insulation fiasco has been caused by fly-by-night installers not following standard protocol for the installation of ceiling insulation. There are standards in place which specifically state that insulation of any type must not be installed over halogen downlights and their associated transformers or within a specified distance of exhaust fans. I was informed about these regulations before our ceiling insulation was installed.

Stapling foil insulation into electrical wiring has been the main cause of electrocution of installers and to a lesser extent, others entering the roof space at a later date. (As far as I am aware, RCDs are now compulsory in ALL houses in Queensland, so where were the RCDs in these cases?)

Idiots putting insulation of any type over halogen downlights and transformers has largely been the cause of house fires. Old wiring in houses causes many house fires without the need of adding insulation. The insulation (of any type) just hastens the process.

Regarding electrical wiring in ceiling spaces, we have a modern home, built in 1994, which has a steel frame. The electrical wiring in the roof space is for lights, ceiling fans and exhaust fans. We do not have any halogen (power-wasting) downlights. We have two lighting circuits, one for each end of the house. Both circuits are protected by RCDs (safety switches).

Our meter is on a pole inside our property and we have underground power to our house. The main cable from the meter to the sub-board (housing safety switches and circuit breakers) is in conduit in the roof space (above the insulation). No hot-water heater wiring exists in the roof space.

Our foil insulation has been laid on top of the ceiling battens and between the roof trusses. Access through the roof space is by walking on the roof trusses above the insulation. An air gap exists between the ceiling and the foil insulation. If anything, the foil insulation keeps the wiring cooler by stopping radiant heat from the roof reaching the wiring. The current carried by the electrical wiring is well below its maximum capacity. Access to the actual ceiling or electrical wiring is easily accomplished by simply removing the insulation and replacing it when finished. A recent electrical safety audit carried out on our house revealed that the installation is perfectly safe.

In short, if everything (electrical and insulation) is done according to correct procedures (including the replacement of old and dangerous wiring), then there is no issue. It’s the fly-by-nighters wanting to make a quick buck that have caused most of the problems.

Secondly, I have a comment on the lifespan of CFLs. As stated earlier, our house was built in 1994 and the lights originally consisted of a mixture of incandescent bulbs and 20W and 40W fluorescent lights. We rarely had to replace the incandescent bulbs. Some years ago, we started replacing the incandescent bulbs with CFLs in order to save power. We found that our power bill went down marginally with using the CFLs but we also found that we were replacing the CFLs far more frequently than we had been replacing the incandescent bulbs.

The idea that CFLs outlast incandescent bulbs by a factor of eight is a myth. They often don’t last as long as incandescent bulbs, despite costing up to 10 times the price. So CFLs can be false economy. You might save a little on power but you pay for it in much higher replacement costs.

Bruce Pierson,
Dundathu, Qld.

False notions
of high fidelity

Reading through Steve Adler’s letter about digital radio (May 2010 issue), I was struck by the phrase “so good you can hear the announcer breathe”. Oh spare us from this notion of high fidelity! This old broadcasting man is fed up with the current fashion for radio people nearly swallowing the mike and treating us to popping Ps, clicking saliva and breath noises.

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