Environmental Engineering Reference
In-Depth Information
structure,.where.attached.to.building.surfaces;.where.concealed.or.they.run.through.
holes.in.walls,.ceilings,.or.loors;.or.where.they.run.through.doorways,.windows,.or.
similar. openings.. Flexible. cords. must. be. connected. to. devices. and. ittings. so. that.
strain. relief. is. provided. that. will. prevent. force. from. being. directly. transmitted. to.
joints.or.terminal.screws.
A. grounding. electrode. conductor. must. be. used. for. a. grounding. system. to. con-
nect.both.the.equipment.grounding.conductor.and.the.grounded.circuit.conductor.to.
the.grounding.electrode..Both.the.equipment.grounding.conductor.and.the.ground-
ing. electrode. conductor. must. be. connected. to. the. ground. circuit. conductor. on. the.
supply.side.of.the.service.disconnecting.means.or.on.the.supply.side.of.the.system.
disconnecting.means.or.over-current.devices.if.the.system.is.separately.derived..For.
ungrounded.service-supplied.systems,.the.equipment.grounding.conductor.must.be.
connected.to.the.grounding.electrode.conductor.at.the.service.equipment..The.path.to.
ground.from.circuits,.equipment,.and.enclosures.will.be.permanent.and.continuous.
Electrical. equipment. shall. be. free. from. recognized. hazards. that. are. likely. to.
cause. death. or. serious. physical. harm.. Each. disconnecting. means. shall. be. legibly.
marked.to.indicate.its.purpose,.unless.it.is.located.so.the.purpose.is.evident..Listed.
or.labeled.equipment.must.be.used.or.installed.in.accordance.with.any.instructions.
included.in.the.listing.or.labeling..Unused.openings.in.cabinets,.boxes,.and.ittings.
must.be.effectively.closed.
Safety-related.work.practices.must.be.employed.to.prevent.electric.shock.or.other.
related.injuries.resulting.from.either.direct.or.indirect.electrical.contact.when.work.is.
performed.near.or.on.equipment.of.circuits.that.are.or.may.be.energized..Electrical.
safety-related.work.practices.cover.both.qualiied.persons.(those.who.have.training.
in.avoiding.the.electrical.hazards.of.working.on.or.near.exposed.energized.parts).and.
unqualiied.persons.(those.with.little.or.no.such.training).(see.Figure 25.7).
There.must. be. written. lockout.and/or. tagout.procedures.. Overhead. power. lines.
must.be.de-energized.and.grounded.by.the.owner.or.operator.of.the.lines.or.other.
protective.measures.must.be.provided.before.work.is.started..Protective.measures,.
such.as.guarding.or.insulating.the.lines,.must.be.designed.to.prevent.employees.from.
contacting.the.lines.
Unqualiied.employees.and.mechanical.equipment.must.be.at.least.10.feet.away.
from.overhead.power.lines..If.the.voltage.exceeds.50,000.volts,.the.clearance.dis-
tance.should.be.increased.4.inches.for.each.10,000.volts..OSHA.requires.portable.
ladders.to.have.nonconductive.side.rails.if.used.by.employees.who.would.be.working.
where.they.might.contact.exposed.energized.circuit.parts..Also,.conductors.must.be.
spliced.or.joined.either.with.devices.identiied.for.such.use,.or.by.brazing,.welding,.
or.soldering.with.a.fusible.alloy.or.metal..All.splices,.joints,.and.free.ends.of.conduc-
tors.must.be.covered.with.insulation.equivalent.to.that.of.the.conductor.or.with.an.
insulating.device.suitable.for.the.purpose.
All.portable.electrical.tools.and.equipment.must.be.grounded.or.of.double.insu-
lated. type.. Electrical. appliances. such. as. vacuum. cleaners,. polishers,. and. vending.
machines. must. be. grounded.. Extension. cords. being. used. must. have. a. grounding.
conductor.. Multiple. plug. adapters. are. prohibited.. Ground-fault. circuit. interrupters.
should.be.installed.on.each.temporary.15-.or.20-ampere,.120-volt.AC.circuit.at.loca-
tions.where.construction,.demolition,.modiications,.alterations,.or.excavations.are.
