Here you can find the general guidelines for execution at site.

Selection of Material

Selection of material shall be on the basis of suitability for the project and policies of client, with the criteria’s like latest technology, durable design, good payback period,

Execution

We shall follow correct and efficient work methods to avoid duplication of work, wastage of material and labour cost. At this stage the execution commences.
First is the laying of pipes in slab. We shall design some rules to help us. No body shall be allowed to differ from the piping layout drawing issued at site. In fact the Arial photo of the slab before casting should coincide with our drawing with 100% accuracy.

  1. All pipes emerging from any junction box, fan box, bend or socket should be at right angle and straight for at least 12” length.
  2. Bind the pipe at every start and end of pipe. The additional binding shall be provided at start and end of bends also.
  3. All boxes in slab should be 2 ½” deep.
  4. All pipe drops in beam should be in plumb and straight, with socket at the end touching beam bottom. To avoid lifting of pipe from beam bottom, due to addition of covering pieces in the slab below steel, the length of drop should be 1” more than the beam depth. This keeps the firm contact between sockets at the end of drop and beam bottom. If these pipe drops loose their contact with beam bottom then it is similar to having a nicely built tunnel with plugged openings.
  5. The vertical pipes shall have binding at top and bottom.
  6. In market springs for bending the PVC pipes are available. We must use these for bending the pipes. This method is help full in removing the tensions on the wall of bent pipe. In presence of such tension the pipes tend to move away from the boxes, and spoil the work. At the same time the radius of bend made manually with the help of spring shall not be less than 12”.
  7. We shall construct brick protection for the pipes emerging from floor slab for being used in upper floor walls.

Inspection

At this stage inspection of piping is to be done.
Inspection of the slab piping shall be done at every level to avoid any silly mistakes. All the rules defined in previous stage are to be conveyed to workers. In addition we shall distribute the responsibility of checking their work by these rules to individual workers. Out of four workers first shall check for straightness and binding of pipes.

  1. Second shall check drops in beams.
  2. Third shall check for correctness of piping layout as per drawing.
  3. And forth one shall see for any avoidable tensions in pipe and need of using spring for bending.
  4. As a procedure all four workers shall report to respective contractor with any deviation from the rules and balance work.
  5. It is contractor’s responsibility to inform me about any deviation and balance work before I point it out. Hence contractor shall not give me opportunity point out faults other than those he has already acted upon.
  6. Any brakeage in pipes and boxes during casting of slab shall be corrected there and then with the report of the same in writing on respective drawing.

Recording of as built drawings and measurement.

At this stage contractor shall record all the changes made in piping layouts if any on the copy of drawing it self. This will come handy at the time of wiring. In addition contractor  shall record the quantity of material used in the slab to help us in finding correct amount invested in and to have feel of the budgets and balances.

Wall piping

During this stage we do the wall piping. The heights of switchboards and light points from f f l are defined. Sizes of the boxes are also defined and we have to follow the same.
The rules for wall piping can be defined as.

  1. Horizontal pipe should not be at the bottom of the wall. It should be at beam bottom.
  2. All pipes should be either horizontal or vertical. Slanting pipes should be avoided.
  3. Use of Cutting machine is compulsory.
  4. No R C C member should be cut without written permission from site in charge.
  5. All sides of the switch boxes should be at right angles and depth of the box should be 2” minimum.
  6. PVC junction boxes should be of 1 ¼” depth.
  7. The site in charge should be consulted for the thickness of the plaster and f f l in each individual room. The discussion should be recorded.
  8. A sketch for the piping in the wall should be prepared. This will also help at the time wiring.
  9. The responsibility of meson is to give finishing touch to the boxes fixed by the electrical contractor. The proper line and level of the boxes is contractor’s responsibility.
  10. The pipe ends should be plugged properly and any body on site that finds any of the unplugged openings shall inform the electrical contractor.
  11. All the boxes should be cleaned and filled with waste cloth as soon as the plastering job is completed.
  12. G I wires are to be inserted in each pipe as early as possible after plastering to locate any jammed pipes. If time lag between plastering and wiring is more than two months then the GI wires may be replaced by nylon thread, as there is a possibility of rusting and breaking of G I wires.

Wiring

Usage of proper size of wires for proper job is the goal in this stage.
Practically it is very difficult to find the size of the wire on site. So to simplify the process of inspection we are using colours for the phase wires as follows. Here we are not waiving any colour code set by the I E rules. For every neutral wire of any size the colour will be black and for earthing green.
WIRES AND THEIR COLOUR

1.5 mm2
Point wiring
Yellow
2.5 mm2 Sub main & 16 A Point Red
4 mm2 Boiler and AC point Blue
                               
                               IE Rules say


Color
Purpose
Red, Yellow, Blue Phase wires
Black Neutral
Green Earhing

This arrangement of colour will help is reducing wastage and checking time.

One can easily find out the size of the wires used and correctness of size by just looking at the box. This will be possible because all the phase wires of the particular size will be available at site in defined colour only.

The next issue is of the length of the wires in side the boxes. Every of the wiremen have different habits for keeping the length of wires. Ideally the length of wire in any box or Distribution board shall be equal to sum of the height, depth and width of the box. For a box of size 10 x 8 x 2 the wire length shall be 20”. The excess length is either cut at the time of connection or are bundled and pressed in the respective box, causing bulging of cover plate.

Connection of wires is the next issue where a special attention is needed. Normally we were using single strand or 3 strand wires of 1/18, 3/20, 7/20 rating. Now we are changing over to multi-strand flexible wires. The basic and only negative point in these wires is that that if the wire are not properly twisted before connecting in switch, the loose strand protruding out of the connection may touch another wire or switch part and fault occurs. The length of removed insulation shall be just adequate to permit proper twisting and connection. Use of knife for removing the insulation shall be avoided.

Normally the looping within the switchboard is not attended properly. The recommended size of wire for looping of mains from switch to switch shall of the size of the mains wire running up to the switchboard. It is advisable to connect the mains phase wire to the switch controlling the plug point on the board. For all light and fan points the maximum load is limited up to 100 watts, but for plug point the load may go up to 1200 watts, which is the highest load within that switch board and hence the plug shall be honoured by connecting mains wire to the switch controlling the plug.

Connections

Now for M C B D B in addition to keeping limited length of wires it is also necessary to have proper binding of bunch of wires. Since the wire sizes in the D B are 2.5 and 4 mm2 it is recommended to use fork type lugs on the wire ends connecting to M C B’s and pin type lugs on wire end connected to earth and neutral links. These lugs are crimping type and are to be crimped using crimping pliers only.

We also recommend using ferrule numbers on the wires emerging out of the D. B. to mark the name of the switchboard they are reaching.

The points I have mentioned in my talk are limited to those, which I feel necessary at this point of time. But these are not the only rules to be followed. I do always discuss all these and many others as and when required with the respective contractors during my site visits.

Specifically I have not touched any of the I E rules, as many of us will be well conversant with them. And by the electrical contracting license, which many of us are holding, it is mandatory to everybody to abide by all related rules.

All the rules I have talked are not to be taken as rules, which every electrical contractor shall follow while doing job with me, only, but these rules will help every body everywhere in giving out better electrification.

So coming note at the beginning of my talk we have the goal of delivering pure distortion free but invisible electrical supply to our customers in form of greater visualization by lights, better motivation by well performing lifts and pumps. We will be achieving this by controlling and adopting good working methods and practices during execution.
So let us make the electrical problems invisible from our site.