Wiring systems

[Scott_boy]

Hi guys. Im a adult apprentice currently on my 2nd year as a sparky and i am starting to struggle with the college work, help needed!!!

I have to provide two possible wiring systems for underground and two for overhead in my college project. They are to supply an external pump house with 3 phase motors. The pump house is to be fed from a sub board in a warehouse.

I thought of SWA for underground and also maybe split conncentric in a duct or some form of protection. For overhead i have thought of using a cantenary wire but unsure of what wiring to use. I have to give plus and negative points to support my answers.

Any help would be much appreciated!!
Thanks.

 

[guest119]

PVC swa only for underground, takes the frost without becoming porus.
You need to specify distance for overhead, accessible to traffic etc, see on site guide.

Boydy

 

[Scott_boy]

thanks for the reply. i need 2 possibilitys for underground and then stick with one. going to go with SWA but i need another one just to have. thats why i chose split concentric, doesnt need to be 100% suitable, just a possibility.

Overhead span is 8 to 10 metres. No public traffic, maybe site vehicles or forklift though. we were told we can use poles to mount it onto, so possiblilty of bare conductors mite be an option. i dont know???!!!

 

[Richard Burns]

SWA would be the wiring of choice for underground installation , once you have a cut in place then the wiring choice is fairly wide but still go for a robust solution that will not suffer from water ingress or frost.

For catenary overhead cables you should be looking at flexibility of cable to prevent undue strain whilst moving, perhaps silicone insulated conductors, also consider exposure to UV light and weather (use cables with carbon black on the sheath construction) as boydy says look at the OSG for the recommended span support interval and guidance on wiring.
Over the distance stated catenary wires with sheath abrasion avoidance potential sound the best option.

 

[Deleted member 26818]

You could use either SWA buried direct, or in ducting, or unarmoured cables in ducting.
For over head, you could use a catenary wire, or install some for of cable support system, such as ladder rack.

 

[Scott_boy]

Hi guys, for all your info. i went with SWA for my underground choice but had to choose any other wiring system that could even be a slight possibilty, so i just said SY cable in a duct but SWA was my final choice. Overhead system for one option i went with PVC singles in steel conduit on a gantry system as the span is 25M, And then my final choice was SWA on a catenary wire as it was only a 6mm cable so when i calculated the weight and matched it to the catenary it seemed ok. Lecturer said it seemed ok. The 2 choices for each were only a learning lesson for us to actually think about advantages and disadvantages of different systems.