Cable tray fittings : Names and functions

Cable tray fittings and accessories : Names and functions 

Cable tray fittings and accessories

1) Elbow / Bend

 there are three types of elbows :

Horizontal elbow (45)

It is a fitting that is used for changing the direction of cable tray by a degree of 45 .

Horizontal elbow (90)

It is a fitting that is used for changing the direction of cable tray by a degree of 90 .

vertical elbow

It is used for changing the direction of cable tray to a different plane . 

inside vertical elbow : changes direction upward from the horizontal plane .

Outside vertical elbow : changes direction downward from the horizontal plane .

  2) Tee Connection

It is a fitting that is used for joining three cable trays in three directions at 90 degree between each tray and other in the same plane .

 3) Reducer 

It is a fitting that is used for joining two cable trays of different widths in the same plane  and there are three types of reducers :
straight reducer
Left hand reducer : when viewed from the wide end , it has a straight side from the left .
right hand reducer : when viewed from the wide end , it has a straight side from the right 

 4) Cross connection

It is a fitting that is used for joining four cable trays in four directions at 90 degree between each tray and other in the same plane .

 5) Riser Bend

Types of riser bend :
Internal Riser : it is used for changing the direction of the cable tray from a lower level to the upper level .
External Riser : it is used for changing the direction of the cable tray from the upper level to the lower level .

internal and external riser

and all previous fittings are shown in the following figure :

Cable tray fitting and accessories

 6) Connectors / splice plates / couplers

These are fittings that are used to join two sections of cable trays to each other .

There are three types of connectors as follows 

• straight connectors
• angle connectors
• adjustable connectors

 Straight Connector :

- Angle Connector :

 - Adjustable connector : it allows changes in elevation ehere standard vertical fittings are not applicable and they include two types : 

• Horizontal adjustable connector : it adapts to changes in direction in a horizental plane .

• Vertical adjustable connector :  adapts to changes in direction in a vertical plane 

Horizontal adjustable connector

Vertical adjustable connector

 7) Cable Tray Cover 

the cover protect the cables inside the cable tray from mechanical damage , heavy accumulation of dust and direct sunlight .
it also isolates cables from fires and radio frequency from interference. 

 types of tray covers 

- solid cover (plain or flanged) : 

provides maximum mechanical protection for cables with limited heat build up.

 - ventilated cover (plain or flanged) : provides excellent mechanical protection while allowing heat produced by cables to dissipate .

 - peaked cover (flanged) :

It is used in locations where there is a possibility of heavy rains 

Note : only cable trays containing instrument and communications cables may have unventilated covers .

Types of cover clamps :

Cable trays are used with a cover in outdoor applications and in mechanical rooms

  8) Fish plate 

it is a fitting that is used for extra strength when joining cable tray sections and also can protect cables from cut edges .

Fish plate joins tray sections

  9) End Plate

it is a fitting that is fixed to the end of the cable tray or ladder to lock it giving a neater appearance .

 10) Dividers / barrier strips

divider is a fitting that is installed inside the cable tray to physically separate different types or groups of cables within the same tray .

Barrier strips are also used to separate cable systems  above and below 600 volts installed in the same cable tray as per NEC 392.6(F).

 11) Flexible expansion coupler

it is a fitting that is installed between two cable trays or ladders across the expansion joints of the building structure for the following reasons :

• To compensate for the  variation of the length of the cable tray or ladder due to thermal expansion or contraction resulting from changes in temperature 
• To provide a semi-flexible joint when cable trays or ladders span two separate structures between them there is a possible relative movement. 

 12) Hold down clamps and clips 

They are ysed for fixing cable ladders to heavy duty  trapeze hangers , cantilever arms and channels .

Hold down clamps

Hold down clips

 13) Dtop-out plate 

It is a fitting that is installed in cable ladders to support the cables as they exit the ladder down between the rungs .

Drop-out plates can be located either on the side or at the bottom of cable ladder .

  14) Tray to box splice plate 

It is used to attach the end of cable tray to a distribution box or control panel .

 15) Roofing Bolts 

most of cable tray fittings are fastened to the tray using bolts and  these bolts are mushroom-head steel roofing type bolts and should be mounted with head inside the tray and washers and nuts located on the outside the tray to prevent injury to cable insulation . 

   Threaded rod   

It is a rod that is used for hanging cable trays or ladders directly to

 the ceiling from anchors and is fastened to the horizental support channel (strut channel) by using nuts and washers

The rod's diameter is choosed depending on the weight of the cables installed on the tray in addition to the weight of  the tray itself. 

 17) Support Brackets

:  support brackets are used for supporting cable trays on walls ,ceiling ,toproof and underfloor .

 18) protection strip

It is a strip that is used to protect the cables from cut edges as they enter or exit from the cable tray .

 19) Step down splice plate

It is used for joining cable tray/ladder sections having side rails of different heights .

  20) offset reducing connector

 It is used for joining cable tray/ladder sections of different widths , so :

•  To form an offset reduction, use a reducing connector.
• To form a straight reduction, use a pair (2) of reducing connectors.

 21) junction box plate 

It is used for the installation of junction box in cable trays.