Estimating a small repair shop: BOQ, GST and a suspiciously low rival quote
A 60 m2 electronics repair shop is to be wired on a three-phase 415 V supply. The scope is 12 LED fittings of 18 W, 6 ceiling fans of 70 W, 8 six-ampere socket outlets, 2 sixteen-ampere power points (one for a soldering station, one for a test bench), and one 1.5 TR split air-conditioner. Wiring is to be concealed PVC conduit, with an eight-way distribution board, a 40 A main switch, an RCCB and one earth electrode. The owner has a budget of 85,000 rupees including taxes and wants LED fittings and fans supplied and installed by the contractor. The contractor's rates are: 1.5 mm2 wire 1,850 per 90 m coil, 2.5 mm2 wire 2,900 per coil, 4 mm2 wire 4,400 per coil, 25 mm conduit 55 per metre, modular switches and plates about 10,000 for the lot, DB with MCBs and RCCB 6,200, LED fitting 650 each, fan 1,450 each, earthing set 3,800, consumables 1,500. Labour is charged at 20 percent of material, overheads and profit at 10 percent, and GST at 18 percent. A rival has quoted 62,000 rupees for the same scope.
1. Build the bill of quantities with quantities and amounts, then compute the contractor's quoted price and compare it with the budget.
Read the worked answer
Bill of quantities
| Item | Qty | Rate | Amount |
|---|---|---|---|
| 1.5 mm2 wire (lighting) | 3 coils | 1,850 | 5,550 |
| 2.5 mm2 wire (sockets) | 3 coils | 2,900 | 8,700 |
| 4 mm2 wire (AC and submain) | 1 coil | 4,400 | 4,400 |
| 25 mm PVC conduit | 170 m | 55 | 9,350 |
| Conduit accessories and boxes | lot | - | 1,800 |
| Modular switches, sockets, plates | lot | - | 10,000 |
| 8-way DB, 40 A main, MCBs, 40 A/30 mA RCCB | lot | - | 6,200 |
| LED fittings | 12 | 650 | 7,800 |
| Fans | 6 | 1,450 | 8,700 |
| Earthing set | 1 | 3,800 | 3,800 |
| Consumables | lot | - | 1,500 |
| Material subtotal | 67,800 |
Labour 20 percent = 13,560; subtotal 81,360. Overheads and profit 10 percent = 8,136; subtotal 89,496. GST 18 percent = 16,109. Quoted price = 1,05,605 rupees, which is about 20,600 above the owner's budget.
Quantity check. Three coils of 1.5 mm2 give 270 m, about 22 m per lighting point including drops, which is reasonable for 12 fittings and 6 fans in 60 m2. The conduit length follows from about 20 points at roughly 8 m average plus a 15 m submain.
2. The budget cannot be raised. Propose how to bring the price within 85,000 rupees without compromising safety, and show the revised calculation.
Read the worked answer
Reduce scope, not safety. The two items the owner can legitimately supply himself are the fittings and the fans, since these are appliances and not part of the wiring installation. Deduct 12 x 650 = 7,800 and 6 x 1,450 = 8,700, total 16,500 of material.
Revised material: 67,800 - 16,500 = 51,300. Labour 20 percent = 10,260; subtotal 61,560. Overheads and profit 10 percent = 6,156; subtotal 67,716. GST 18 percent = 12,189. Revised price = 79,905 rupees, leaving about 5,000 of headroom in the 85,000 budget.
What must not be cut. The RCCB, the earthing set, the 2.5 mm2 socket wiring, the 4 mm2 AC circuit and the test certificate stay in the quote. If more saving is needed, reduce the number of socket outlets from 8 to 6, or defer the second 16 A power point to a later phase, and state the phase division clearly in the quotation.
Commercial note. Put in writing that the wiring is guaranteed for one year, that fittings supplied by the owner carry the manufacturer's warranty only, and that the final bill will be at measured quantities, not at the lump sum, if the owner changes the layout during the work. Headroom in the budget protects against a 5 to 8 percent material price movement.
3. The owner asks why the rival quote is 62,000 rupees. Analyse how such a quote is usually built and what you would tell the owner.
Read the worked answer
Where the difference hides. The gap of roughly 18,000 to 43,000 rupees against a legitimate price cannot come from efficiency alone; it usually comes from omitted items and downgraded materials:
- No earthing set and no RCCB, worth about 10,000, which are exactly the two items that protect life.
- 1.0 mm2 wire for lighting and 1.5 mm2 for sockets, below the minimum sizes that IS 732 expects for lighting and power circuits; the copper saving is real but the cable runs hot and the drop is higher.
- No conduit, or surface wiring in thin casing, which is cheaper to install and to abandon.
- Non-standard or unmarked MCBs with no test certificate, and no insulation resistance or earth resistance test before handover.
- Labour shown separately and paid in cash, with GST not invoiced.
What to tell the owner. Compare the two quotes item by item, not by total. Ask the rival for his earthing detail, cable sizes, MCB make and test certificate; a genuine contractor will supply them, and the price will climb towards yours. Point out that a shop with computers and a soldering station has a real fire risk, that insurance may be refused if the wiring does not meet the code, and that redoing hidden wiring later costs two to three times the saving.
Close the sale. Offer the phased option at 79,905 rupees with the same specification, a written test report and a one-year guarantee, and let the owner compare like with like.