Cable Tray Sizing Formula

On tue dec 2 2014 at 7 52 pm electrical notes articles wrote.

Cable tray sizing formula.

Per nec tray sizing instructions 1 insure that macros have been enabled. Mm x 2 219 98 sq. An example how to calculate voltage drop and size of electrical cable photo credit. Tray design depth sum of od in total cross sectional areas of all cables.

The cable tray sizing equals the width times the loading depth. Total diameter of all cables laying in tray 119 4 137 2 54 mm. A 50 fill ratio should equal the maximum number of cables pulled in a given cross section. Mm x 4 62 77 sq.

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. 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. Practical guide on the amount of cable weight that can be installed tested in accordance with nema ve 1 csa e222 2 126 1. 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. Total sum of the diameters. 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. Number of cable per trench is 1 number of run of cable is 1 run.

The sum of the cross sectional areas of all cables cannot exceed 50 of the trays fill area. Cable is directed buried in ground in trench at the depth of 1 meter ground temperature is approximate 35 deg. 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.

Diameter of 400sq mm cable 2x68 6 137 2 mm. Total diameter of all cables laying in tray 340 6mm. Diameter of 25sq mm cable no of cable x outer diameter of each cable. Chart is based on 50 fill of 4 utp category 6 cable o d 21 033lbs ft not maximum loading weight for the tray.

The installation will use cat cable at 19 in diameter 20 lb. 4 choose the inside tray depth being specified. Cable tray is sized based on the number and type of cables required for the current and future need. Get the cable size corresponding to this derated current from the catalog.

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. A inside tray area in in 2 d cable diameter in inches f fill ratio in n number of cables the formula is n f a 100 d 2 2 π example.