Street Lighting Design

Hi All

Looking for help here, I am currently designing a column lighting for a community used playground which requires 12 (150W) SON lamps.

My plan is to have 4 son lamps per circuit. Wiring to be by loops with protection per lamp. Control is to be by time swicth with photocell overide during dark hours.

My question is:
*Using Amtech, the cable schedule indicates 2c cables, I am suppose we require a separate core for earthing or is it ok to use the wire armour as earth.
*Does any one has any design schematic which I can take a look at?
* Does anybody have the wiring diagram for combination of photocell and time switch?
* apart from ensuring cable sizes and protection and discrimination, is there any specific requirement regarding street lighting.

I have never done this type of design before now.

ANy assistance will be appreciated.

How To Determine Energy Savings - Help

Hi all, I am having to carry out an energy savings survey from my client who has over 200 motors some of which are very very old. I have look at the motors and they are all small drives with a handful of 22kW, 7kW, 5.5kW and 4kW. All others are below these ratings. I am looking at ddeveloping an approach to looking at this. Obviously, I don't want to carry out a survey on all motors.

What I have in mind is to review the asset schedule and; to identify the bigger motors, carry out a physical survey of these bigger motors reviewing the eff, pf and starter types including the application. The idea is to change motors with varying load to VSDs where they are not and also to propose more efficient motors.

Any idea on what should be looked at typically or how to approcah this?

Substation And Earthing

Hi All,

I have an issue that has kept me busy for sometime. i will appreciate so advise/help here.

I am having a substation installed in a site xformer = 11Kv/400v, 500KVA, 400v. The supply authority requires me to terminate my main cable in an LV panel which is part of the transformer and has confirmed that the supply is PME. I am expected to use a 4 x 1c 240mm cables. My main concern is how to determine a suitable earth bond.

Normally by BS7671, we use the size of the suppliers cable but in this instance there is no secondary cable since the LV panel is part of the xformer substation arrangement.

Has anyone worked on such a system before and what did base your earth calculation on?

Response will be really appreciated.

400a Supply

I am planning on installing a 400A supply from a 500KVA transformer substation. The design is for a 4 x 1c 240mm cable, about 120m length. What is the best way to install these cables? single duct for all cables - is this possible. Trefoil will require 3 cables but I have 4 cables. Open escavation, do I need to seperate the cables.

I have checked that if the cables are grouped, derated current will be 319A. My max demand is 250A/phase.

I need some advise from your experiences.

Ze For 500a Supply - Tnc-s

Hi

I am currently designing for electrical installation of a site in UK (not London). The Supply is 500A, the REC will not give me any values for Ze (earth loop impedance). What is a sensible value to assume if I must continue with the design. The substation is within my site.

I will appreciate any advise.