assignment question

[xAlex]

...Yes it's another assignment question, sorry.... If you can HELP I would appriciate:
214M 3 core SWA linked to 11 car park lamps each at 150W SON. 4 lamps on 2 of the phases and 3 on the 3rd. What size SWA do I need. What protective device? What is the Vd. Are there any correction factors for this? Cable is to be buried in trench.
Cheers
Alex

 

[ricicle]

Are you sure it's not 4 core SWA as a Neutral will be required!

 

[xAlex]

...err, yes, of course, ... 4-core is required. (cable selection was part of the question too)(Don't worry, i never plan to design and install car-park lights). ...Thanks.

 

[Spark123]

Are all the lamps at the far end of the cable? Don't forget to correct for discharge lighting.

 

[xAlex]

This is what I got:

TYPE OF CABLE
Design current (per phase) Ib 4x150/230=2.6A
Correction for discharge lighting: x1.8 2.6*1.8=4.68 Amps
Fuse protection: 6A BS EN60898
Other Correction factors: not applicable
Therefore In=6A
Installation method 1
So, cable is 4-core Thermoplastic insulated SWA 6mm - can carry 45 Amps but needs to be 6mm to achieve volt drop <4%.
Volt drop is 25mv/A/m
Vd=(214 x 2.6 x 25) / 1000 equals 6.41 Amps

Lights are distributed across 3 phases so 2 phases with 4x150W, 1 with 3x150W, they are placed 15m apart aprox.