Cable Tray Sizing Formula

A 50 fill ratio should equal the maximum number of cables pulled in a given cross section.

Cable tray sizing formula.

Total diameter of all cables laying in tray 119 4 137 2 54 mm. Cable is directed buried in ground in trench at the depth of 1 meter ground temperature is approximate 35 deg. 4 choose the inside tray depth being specified. Tray design depth sum of od in total cross sectional areas of all cables.

Get the cable size corresponding to this derated current from the catalog. Generally cable tray sizing is correct when it appears 50 full of cable or wire or when it contains a 50 fill of cables or wire. Derating factors will be available in cable catalog. The sum of the cross sectional areas of all cables cannot exceed 50 of the trays fill area.

Calculate cable tray width calculate cable tray area calculate cable tray length calculate cable tray weight calculate remaining width of cable tray calculate remaining area of cable tray free download. Mm x 4 62 77 sq. Cable raceway tray support calculations. Mm x 2 219 98 sq.

Number of cable per trench is 1 number of run of cable is 1 run. Diameter of 25sq mm cable no of cable x outer diameter of each cable. Diameter of 25sq mm cable 3x28 84 mm. The installation will use cat cable at 19 in diameter 20 lb.

An 8awg thhn wire has a cross section of 23 61 square mm 0 03659 square in a 4 awg thw has a cross section of 62 77 square mm 0 09729 square in therefore the wires total cross sectional area is. The cable tray sizing equals the width times the loading depth. Per nec tray sizing instructions 1 insure that macros have been enabled. Quick tray wire mesh cable tray fill table at 50 fill use the following formula to calculate the number of cables that will result in a particular fill ratio where.

Straight section supports installed at 5 foot 1 5m centers are typical. 3 use the pull down menu to choose the type of cables being used and answer any of the pop up questions. I load in kw sqrt 3 v in kv p f a the current obtained has to derated since the cable is designed to operate at a defined temperature. Cable trays may be filled 50 when using control or signal wiring.

Total diameter of all cables laying in tray 340 6mm. Diameter of 400sq mm cable 2x68 6 137 2 mm. An example how to calculate voltage drop and size of electrical cable photo credit. On tue dec 2 2014 at 7 52 pm electrical notes articles wrote.

Chart is based on 50 fill of 4 utp category 6 cable o d 21 033lbs ft not maximum loading weight for the tray. Total sum of the diameters.