Hospitals use cotton
sheets and uniforms, and use bonding extensively operating theatres.
Static charge builds between any two insulating surfaces between an
insulating surface and conducting surface, but not apparent between
two conducting surfaces. Bonding surfaces together with equipotential bonding conduc-
tors prevents build-up static electricity between the surfaces. Most computer systems are sensitive variations
.
Static electricity
Static electricity voltage charge which builds many thousands of
volts between two surfaces when they rub together.
Rubber, which contains proportion graphite, used manufacture
antistatic trolley wheels and surgeons’ boots.
Petrol pumps, operating theatre oxygen masks and car spray booths are
particularly risk because spark these situations may ignite the flam-
mable liquid, powder gas. Lightning dis-
charge currents are the order 20kA, hence the need for lightning con-
ductors vulnerable buildings order discharge the energy safely. Rubber constructed this
manner enables any build-up static charge ‘leak’ away. use
large-diameter pipes, reduce the flow rates liquids and powders and,
therefore, reduce the build-up static charge.1). dangerous situation
occurs when the static charge has built potential capable striking
an arc through the airgap separating the two surfaces.
So how protect ourselves against the risks associated with static
electrical charges? said earlier that build-up static charge not
apparent between two conducting surfaces, and this gives clue the
solution. lightning strike the dis-
charge the thunder cloud, which might have built voltage of
100MV, the general mass earth which zero volts. We
looked Lighting Protection Systems Chapter 13. Many flammable liquids have
the same properties insulators, and therefore liquids, gases, powders
and paints moving through pipes build static charge.514.
A nylon overall and nylon bed sheets build static charge which the
cause the ‘crackle’ when you shake them.
A motor car moving through the air builds static charge which some-
times gives the occupants minor shock they step out and touch the
door handle.
Definition
Static electricity voltage charge
which builds many thousands
of volts between two surfaces when
they rub together.
Static charges build thunderstorm. Increasing
humidity also reduces static charge because the water droplets carry away
the static charge, thus removing the hazard.Electrical installations and wiring systems
329
appropriate, between and years but not exceeding years (Regulation
721.
Computer supplies
Every modern office now contains computers, and many systems are linked
together networked
