Dear John,
I noticed the closeness of 2.52 inches and 64 mm and then I wondered
whether they were trying to fit a metric cable into an old- pre-metric
space or vice-versa.
On another issue from the same article, I wondered about where in
Italy you could buy a 2 inch cable. This would be a most unusual size
in Italy and would have to be a special order as I don't think any
Italian cable maker would routinely make products to inch sizes.
Cheers,
Pat Naughtin
Author of the forthcoming book, Metrication Leaders Guide.
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that they
now save thousands each year when buying, processing, or selling for
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On 2009/08/06, at 4:32 PM, John Frewen-Lord wrote:
As a surveyor in the construction industry (and having worked in
both imperial and metric in the UK, the US, Canada and South
Africa), something about this story doesn't quite ring true.
1. In-the-field tolerances are never less than 1/16" imperial (1.6
mm), or 1 mm metric (at least I've never come across tolerances
tighter than that, and that includes a lot of precision hospital
work). The 2/100ths of an inch is almost exactly 0.5 mm, a
tolerance virtually impossible to achieve on a construction site.
2. The 2.52" is almost exactly 64 mm. Allowing for a tolerance of
say +/- 1 mm, the trench should have been specified at 65 mm.
3. I'm no electrical expert, but I do know that cables when
conducting electricity heat up and expand. Was no allowance made for
this? And would it not have been wise to allow a tiny bit of
airpace between the cable and trench walls to allow air circulation
and help the cable to stay cool(er)?
I wonder if there's more to this story than is being told?
Cheers
John F-L
----- Original Message -----
From: [email protected]
To: U.S. Metric Association
Sent: Thursday, August 06, 2009 12:07 AM
Subject: [USMA:45529] I blew it! (The conversion of 2/100ths of an
inch, that is)
OK, I got my conversion wrong. But I bet we would be using whole
numbers in millimiters if we were using and familiar with metric and
had adopted millimeters for construction as Pat has observed works
best in industry.
-- Ezra
