Wiring Systems and Enclosures Flashcards
What are Cable Baskets used for?
used for cables that have more than basic insulation. examples include SWA,PVC and MICC
What is Cable Tray used for?
Typically used for small industrial and commercial systems with soft skinned cables
What 3 types of conduit is there?
steel
pvc
flex
3 advantages of using conduit?
easily altered
offers mechanical protection
used both commercially and industrially
Why would you use steel conduit?
when strong mechanical protection is needed
why would you use PVC conduit?
used when there is a known risk of damn and corrosion
Why would you used Flex conduit?
used so that vibrations are not transmitted down/through electrical installations
what are the steps to calculate conduit size?
1- identify cable factor for conductor
2- multiple the cable facor by the number of conductors
3- identify the appropriate part of the conduit factor table given by the length of run and number of bends
4- select conduit
What materials is trunking made from?
Plastic and steel
when would you use steel trunking?
used when damp conditions are encountered
when would you install non-metallic trunking?
in corrosive environments.
what is the trunking space factor?
The ratio of the space occupied by all the cables in a trunking to the whole space enclosed by the trunking is known as the space factor.
what percentage should not be exceeded by the trunking space factor?
45%
how do you calculate trunking size?
same working principle as conduit
what are Steel Wire Armour (SWA) cables and where are they used?
PVC insulated steel wire armour cables are used for wiring underground between buildings, for main supplies to dwellings, rising sub-mains and industrial installations. They are used where some mechanical protection of the cable conductors is required.
