I think you've made Mr Prescott's point for him. Could a skilled
amateur have done this? <g>
What testing should be done apart from earth pin of plug to metal
of case? Without knowing exactly what's involved the idea of
pushing HV test voltages around electronics sounds a bit worrying
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
In my previous two jobs, I had some involvement in the electrical
work. For PAT testing, we insisted the contractors turned up with
their own C&G certificates on the first day, and we couldn't find
any NICEIC companies who had qualified PAT testers. We used
independant qualified electricians in the end who did have the
qualification. In one case, we had to get the company rule changed
which had required use of NICEIC contractors - it was changed to
require use of _qualified_ contractors, which in practice ruled out
the NICEIC companies we had been using as they seemed unable to
supply any qualified staff to do work.
The first thing is a check on the equipment being suitable for the
use it is put to. For example, you would fail a PAT test on a hot
air paint stripper with nothing wrong with it if it was being used
as a hair drier. (This is why you must inspect appliances where they
are being used, and not have them brought to some central test
location where such misuse would not be aparent.)
Next is a formal visual inspection. Check the plug, lead, casing,
etc for signs of damage, and also check the socket outlet for
signs of overheating (might show up there rather than on the plug).
Check plug fuse rating and that fuse is marked with appropriate
BS and in the case of BS1362, it must also be marked ASTA approved
(diamond symbol). For a rewirable plug, remove the top and check
connections and cord grip. If the appliance is being checked prior
to being sold, the plug must have sleeved pins. In any case, the
plug must have a broadened base to discourage fingers being wrapped
round underneath it during withdrawal (this change came in the
1950's -- would need to be a very old plug to fail that).
Check the appliance conforms to IP2X (no finger can reach any live
parts). A common failure here are old bar heaters where the grill
has too wide spacing. The silica glass tube of a radiant element
counts as a live part for this check. Lampholders are excluded from
Note the general condition of the appliance, how quickly it is
wearing out, and if it will thus merit more frequent inspections
than it would otherwise get. This implies some record keeping.
You might fail an appliance because it is of inappropriate
quality, e.g. a domestic kettle might not be up to continuous use
in an office, or would only be so with very high frequency of
You have now done the most important part of the test -- the formal
visual inspection. This is the part which picks up some 95% of test
failures. This is the part which is skipped by people who don't know
how to do a PAT test. The only tool required was a screwdriver.
You do not go any further with the testing if there are any failures
here -- indeed it is dangerous to do so.
The next stage is to actually use an appliance tester. How you test
the equipment depends on lots of things relating to the type of
equipment and how it is earthed. In some cases, no testing is possible.
For Class I (earthed metal case) appliances, one of the tests does
involve checking the earth continuity, but the method varies depending
how much current your tester can provide to do this. You don't use
HV test voltages around electronics unless the appliance claims to
conform to EN 60950 or BS 7002, in which case it has been designed
to withstand the 500VDC test. Instead, you do an earth leakage test.
Again, you should keep records to check for deterioration, and spot
that more frequent testing may be required. In the case of a rapid
deterioration, even though still within spec, this could be the cause
for a test failure pending discovery of the cause. Likewise, records
could show over time that you don't need to test so often.
Finally, it's a good idea to do a functional check, because otherwise
you will get laughed at for passing an electric drill which simply
doesn't turn, although it may not necessarily be unsafe.
BTW -- this is from memory, and I haven't done it for some time, so
I may have missed some parts out.
Crude, crude. The wonderful George Goble website, which has, unfortunately,
been removed by his masters at Purdue university (since June)showed video
clips of him lighting barbecues with a gallon or two of liquid oxygen. The
number of US states that permitted him to do this was dropping however! Mad
as a hatter and there aren't enough people like him in the world.
(anti-spam is as easy as 1-2-3 - not)
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