MAINS & SUB-MAINS
Let the power flow!
So you have picked up a project and all you have is a single line with circuit breakers… it’s up to you to join the dots.
Submain work is broken into 2 parts. The take-off phase and the sizing phase.
The Take-Off Phase
In the take-off phase, firstly identify each cable (circuit). Keep it simple and sequential; numbers work best. Refer to your single line drawing and label each cable.
Then record the technical data for each cable on a spread sheet (size of the circuit breaker, route length, type of cable and rating of the cable… etc.).
Once you have this information you can move onto the sizing phase.
The Sizing Phase
Once you know your route lengths, circuit breaker ratings, cable type… you can calculate your cable size for the required load, volt drop and fault loop requirements. Utilize ASNZS3008 for the calculations required. Utilizing either a custom made spread sheet or reputable digital product to assist in automating the calculations will greatly assist in this process.
Once you have selected the cable sizing and configurations to meet the design requirements you will be able to