This is only a preview of the April 2010 issue of Silicon Chip. You can view 32 of the 104 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "FAQs On The Web Server In A Box (WIB)":
Items relevant to "Capacitor Leakage Adaptor For DMMs":
Items relevant to "A 1000:1 EHT Probe":
Items relevant to "Digital Audio Signal Generator, Pt.2":
Purchase a printed copy of this issue for $10.00. |
SILICON
SILIC
CHIP
www.siliconchip.com.au
Publisher & Editor-in-Chief
Leo Simpson, B.Bus., FAICD
Production Manager
Greg Swain, B.Sc. (Hons.)
Technical Editor
John Clarke, B.E.(Elec.)
Technical Staff
Ross Tester
Jim Rowe, B.A., B.Sc
Mauro Grassi, B.Sc. (Hons), Ph.D
Nicholas Vinen
Photography
Ross Tester
Reader Services
Ann Morris
Advertising Enquiries
Glyn Smith
Phone (02) 9939 3295
Mobile 0431 792 293
glyn<at>siliconchip.com.au
Regular Contributors
Brendan Akhurst
Rodney Champness, VK3UG
Mike Sheriff, B.Sc, VK2YFK
Stan Swan
SILICON CHIP is published 12 times
a year by Silicon Chip Publications
Pty Ltd. ACN 003 205 490. ABN 49
003 205 490. All material is copyright ©. No part of this publication
may be reproduced without the written consent of the publisher.
Printing: Hannanprint, Noble Park,
Victoria.
Distribution: Network Distribution
Company.
Subscription rates: $94.50 per year
in Australia. For overseas rates, see
the order form in this issue.
Editorial office:
Unit 1, 234 Harbord Rd,
Brookvale, NSW 2100.
Postal address: PO Box 139,
Collaroy Beach, NSW 2097.
Phone (02) 9939 3295.
Fax (02) 9939 2648.
E-mail: silicon<at>siliconchip.com.au
ISSN 1030-2662
Recommended and maximum price only.
2 Silicon Chip
Publisher’s Letter
The Federal Government’s
insulation scheme is a tragedy
Back when the Federal Government’s roof insulation
scheme was first mooted I had some misgivings about
whether taxpayer funds should be spent in this way but
I let it pass. After all, I have similar misgivings whenever
any government announces any scheme to “fix” a problem, especially when it involves direct subsidies to particular companies or to selected parts of the community.
Having said that, I don’t think anyone could have
imagined how bad the roofing insulation scheme would
turn out to be. Last year I saw the press releases put out by NECA (National Electrical & Communications Association) and other relevant bodies, drawing attention
to the safety risks but again, I did not conceive how crazy it would become. For
example, I did not think that anyone would be silly enough to use aluminium foil
insulation laid over ceiling joists and inevitably, over electrical wiring. Nor did I
dream that such foil insulation would be installed using staple guns – the risk of
shock and electrocution just beggars belief!
But it got worse – much worse! We now know about the fire risk. At the time
of writing, there have been more than 100 house fires where the installation of
insulation is suspected to be the main cause. However, while halogen light fittings
and their transformers have often been implicated, that is not the whole story. In
fact, it could be that electrical wiring which originally was quite safe is now rendered dangerous because it can now run much hotter. People do not realise that
the Australian wiring standards (AS:NZS 3000) set the amount of current that can
pass through power circuits on the basis that the wiring is sitting in free-air, ie,
well-ventilated.
Furthermore, much of this roofing insulation has been installed in homes which
are quite old. Often these houses have sub-standard wiring where the cabling uses
cotton-covered rubber or vulcanised rubber insulation. This stuff is a fire hazard
anyway but will be more so if it has been disturbed by people moving about in
the roof space, installing insulation! And now that such old wiring is covered by
insulation, it is more likely to fail, even if it hasn’t been disturbed.
Even if none of these problems were in existence, it seems silly to install any form
of insulation in the roof space so that much of the electrical wiring is concealed.
It means that it becomes difficult to do any repairs in future.
So what to do now? The Federal Government has now announced that it will
remove aluminium foil insulation from all homes or failing that, it will have RCD
safety switches installed to combat the risk of electrocution. Well, yet again, the
Government simply doesn’t realise the full extent of the problem. NECA has just
released a press release saying that safety switches are not the solution. Indeed,
they are correct although they haven’t said why.
In fact, RCDs can only protect the house wiring which is downside of the meter
box. They cannot protect against the electrocution risk from the main 230VAC feed
cable coming in from the street. It is also safe to say that you would need a qualified
electrician to inspect the roof space and identify the main feed cable – that is just
not going to happen. Furthermore, RCDs cannot be used to protect wiring which
feeds hot water systems so you potentially have a number of electrical circuits in
the roof which cannot be protected. Even if they are installed, RCDs will not mitigate the risk of fire in sub-standard wiring. With that in mind, there is no solution
other than removing all foil insulation installed under the Government’s scheme.
But that will not prevent the occurrence of fires because insulation batts have
been laid over old wiring, halogen lamps or their transformers. And nor can any
number of roof inspections totally remove that risk. There will certainly be more
fires – that is unavoidable. Ultimately, the legal fraternity will have a field day.
It seems to me that the Federal Government’s insulation scheme will go down in
history as one of the worst ever government initiatives since Federation.
Leo Simpson
siliconchip.com.au
|