Brannigans Building Construction CH.7 Non-Fire Building Systems Flashcards
although anhydrous ammonia is transported as nonflammable gas, it has a lower explosive limit of
15%
potential fires may be caused by worn out insulation on wiring that allows what?
conductors to touch, overloaded circuits or bad connections in junction box
one of the very first codes that NFPA published in 1897
national electrical code(nfpa 70)
the metal (copper or aluminum) that distributes electricity throughout building; wiring usually called this
conductors
runs of conductors supplying specific parts of a building and equipment are termed
circuits
amount of electricity flowing through conductors is expressed as
amperes (A)
wires are single or multiple strand conductors that are
bare or sheathed; usually covered with insulation
conductors are tested and rated for
current flow they carry and numbered in terms of gauge under American Wiring Gauge (AWG)
In AWG (American Wiring Gauge) the smaller the number =
larger diameter; i.e. 3 gauge wire will carry 100 A
14 gauge wire is used for
lighting circuits in building
some wiring uses metallic sheathing outside, commonly known as
BX cable
nonmetallic (NM) sheathed cables have taken the generic moniker
Romex (one particular brand of plastic covered wiring)
wiring often runs inside
conduit
durable tubing or an enclosure that protects exposed wiring from physical damage; electrical metallic tubing (EMT), redid metal conduit (RMC) and electric nonmetallic tubing (ENT)
conduit
technically 2 or more insulated conductors
cables
carries cables that are used to cover long distances in large commercial and industrial buildings
elevated cable tray
used to bring different runs of conductors together
junction boxes
brings all of conductors together with the power supply to provide control over the system; sometimes called panelboard
primary electrical service panel
plays critical role in overcurrent protection; gives occupants & FF’s ability to shut down entire system or portion of system
electrical service panel
when operating switches from panel it is best to use what ?
backside of hand w/ face turned away
single use device designed to stop the flow of electricity when excess current is flowing and should be thrown away once blown
fuses
old systems (overcurrent protection) use what?
round “plug” fuses screwed into panel
todays most common overcurrent protection for small residential and commercial buildings
circuit breaker
designed to “trip” circuit when excess current flow is detected; once excess flow issue is resolved it can be restored to provide current
circuit breaker