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

Horizental adjustable connector Cable Tray

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 .