dangerous situation
occurs when the static charge has built potential capable striking
an arc through the airgap separating the two surfaces. We
looked Lighting Protection Systems Chapter 13.
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.
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. Hospitals use cotton
sheets and uniforms, and use bonding extensively operating theatres. lightning strike the dis-
charge the thunder cloud, which might have built voltage of
100MV, the general mass earth which zero volts.
A nylon overall and nylon bed sheets build static charge which the
cause the ‘crackle’ when you shake them.Electrical installations and wiring systems
329
appropriate, between and years but not exceeding years (Regulation
721. use
large-diameter pipes, reduce the flow rates liquids and powders and,
therefore, reduce the build-up static charge. Many flammable liquids have
the same properties insulators, and therefore liquids, gases, powders
and paints moving through pipes build static charge. Rubber constructed this
manner enables any build-up static charge ‘leak’ away.514. Lightning dis-
charge currents are the order 20kA, hence the need for lightning con-
ductors vulnerable buildings order discharge the energy safely.
Definition
Static electricity voltage charge
which builds many thousands
of volts between two surfaces when
they rub together.
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. Bonding surfaces together with equipotential bonding conduc-
tors prevents build-up static electricity between the surfaces. Most computer systems are sensitive variations
. Increasing
humidity also reduces static charge because the water droplets carry away
the static charge, thus removing the hazard.
Static electricity
Static electricity voltage charge which builds many thousands of
volts between two surfaces when they rub together.
Computer supplies
Every modern office now contains computers, and many systems are linked
together networked.
Static charge builds between any two insulating surfaces between an
insulating surface and conducting surface, but not apparent between
two conducting surfaces.
Rubber, which contains proportion graphite, used manufacture
antistatic trolley wheels and surgeons’ boots.1).
Static charges build thunderstorm
