In article ,
Malcolm writes:
|
|| I'm beginning to wonder whether you have the slightest idea what I am
| talking about. The hard hat I have has ear defenders which reduce the
| noise to acceptable decibel levels according to the relevant British
| Standard specification, and a fine wire gauze visor which is hinged so
| that it comes down in front of the whole face and protects it, but
| especially the eyes, from sawdust and larger particles, which can fly
| out at some speed from the saw blade. Indeed, if I'm doing much sawing,
| I will wear goggles as well. But then I'm rather fond of my hearing and
| my eyesight, and looking after them in this way seems good common sense
| to me, as well as being mandatory for professionals and mandatory on
| training courses which instruct you about wearing the necessary
| protective items.

I have some news for you, that you are apparently unaware of. You can
buy quite excellent quality ones that do not need to be attached to a
helmet.

| You should NEVER cut anything heavy above your head, chainsaw, bowsaw
| or light saber. A helmet will not protect you from a broken neck, and
| a light branch will not crack a skull when falling from a mere 1' above
| your head.
|
| Sigh.
|
| No, Nick, of *course* you shouldn't and of *course* it won't.
| But it *will* protect your head against knocks as well as providing a
| very strong framework to which the vital ear defenders and visor can be
| attached. And, believe it or not, things can bang into your head (or
| vice versa) when working around trees even without you cutting anything
| above head level.

Bizarre. You are far more likely to knock your head when poking around
cupboards in the home - and knocking your head in the bath or shower is
a very common cause of death. Do you wear a helmet around the house, and
in the bath, too?

| Obviously they take milliseconds to cut the current, but I think we can
| take it that the laid-down electrical standards used for wiring in
| domestic houses are regarded as sufficient. The stipulated shortest
| disconnection time in "dangerous" areas around the home, e.g. bathrooms
| and gardens, is actually 0.4 seconds (400 milliseconds). which is deemed
| short enough to avoid a life-threatening electric shock. If you
| disagree, then you are saying that the IEE regulations are wrong.
|
| A circuit breaker, or in this instance what is probably better termed a
| residual current device, if properly selected and installed, will make
| it nearly impossible for anyone silly enough to slice through the cable
| supplying a chainsaw, which is what, after all, I have been talking
| about, to receive a dangerous shock. If you don't believe me, I suggest
| you do some experiments, but don't forget to wear a helmet while you do
| them!

I don't give a damn what you do to yourself, but I don't like seeing
you misleading other people into dangerous practices. You clearly
know next to nothing about this area - and, as part of my previous
task at work, I did need to find out about it.

The safety regulations are what is required to reduce the risk to what
the authorities believe is an acceptable level (and all evidence is
that they are right). Such devices do NOT eliminate ALL risk of death
by electric shock; indeed, anyone with an adequate knowledge of either
physiology or physics would know that they can't.

The latter case is simpler, so I shall explain that. There is a very
small chance that cutting a cable (possibly combined with a device that
has the neutral wire incorrectly attached to the casing - a very common
error) will pass the current from the live to the neutral through the
person. In that case, a RCD will NOT trip.

So, everybody except Malcolm, use RCDs but don't trust them to give you
absolute protection from shock. Don't use mains electrical devices in
wet conditions, wear insulating boots (and possibly gloves, too) and
generally be careful. Malcolm is welcome to trust the RCDs absolutely.


Regards,
Nick Maclaren.