Sunday, February 21, 2010

COST ESTIMATION

ESTIMATION GUIDE

  1. Prepare paper, pencils, scale and rulers. Mark papers indicating the panel no., circuit number and the location of the circuit run.

  1. Study plans, drawing and specifications.

2.1 Coordinate with Civil, Mechanical and Architectural Estimators about the following

2.1.1 Height between floors

2.1.2 Drop ceilings and ceiling supports

2.1.3 Height between finish floor and ceilings

2.1.4 Major beams and columns thru which conduits may not pass

2.1.5 Other architectural/civil/mechanical drawings indicating positions of the lights, special outlets or aircon unit equipment.

2.2 Check and make a physical count of the following

2.2.1 Lighting fixtures – number of each type of fixtures

2.2.2 Convenience outlets – duplex

2.2.3 Special outlet

2.2.4 Panel boards – make a complete description of each panel board.

The description should include:

a. main breaker rating or lugs only

b. no. of branches per ampere trip

c. kAIC

2.2.5 Other electrical equipment to be supplied by contractor

2.3 Study carefully the circuit runs and the riser diagram together with the schedule of load.

  1. Determine the approximate length of wire and conduit per circuit.

3.1 For the conduit (each circuit) - measure the length from the last outlet to the panel using the scale. The trace of the route must be followed as per drawing.

3.2 For the wire – measure the length between outlets and the length shall be multiplied by the no. of wires. The sum of the products (lengths x the no of wires) shall be the approximate length of wire.

3.3 Sum up the total length of conduit per size and divide by 3. Round off and add 10%.

3.4 Sum up the total length of wire for each size and divide by 150 to get the no of rolls. Round off and add 10%.

3.5 Set aside the papers and data temporarily.

  1. Determine the approximate length of wire and conduct for the panel homerun to the main panel or main distribution panel.

4.1 Conduits – measure the length of the run. Check the shortest possible route and avoid obstructions. Total length divide 3 and add 5%

4.2 Wire – multiply the length of conduct by the following constants

a. 2- for two-wire single phase

b. 3- for two-wire single phase with neutral

c. 3- for three-wire, 3-phase

d. 4- for 3-phase, 4 wire

  1. Boxes

5.1 Octagonal boxes – provide one box for each lighting fixtures

5.2 Utility box 4”x 2” – provide one box for each switch, duplex outlet or special outlet (small)

5.3 Square box 4” – provide one box if the conduits terminating exceed 4 conduits or special big outlets.

5.4 Square box 4 11/16 – provide one box for one-inch diameter conduits or for special purpose outlets. Also provide one box for multiple (6 or more) terminations.

5.5 Pull boxes – provide one box for every 18 meters of conduits length depending upon the length of run. Other pull boxes may be designated by plans. Check with the designer/consultant about the sizes.

6. Fittings

6.1 For PVC pipes

6.1.1 Couplings – provide 1 coupling for every length plus 1 coupling for every termination.

6.1.2 Elbows – provide 1-900 elbow for every quarter turn for sizes of 32 mm (1 1/4”) and above.

6.1.3 Cement – provide 1 can for every 10 length of conduit.

6.1.4 End bells – provide 1 for every termination.

6.2 For RSC conduits

6.2.1 Coupling – provide 1 additional coupling for every 5 lengths

6.2.2 Elbows- provide one 90-degree elbow every 90-degree turn for sizes of 25 mm (1”) diameter above.

6.2.3 Locknut and bushing – provide one pair for every termination.

6.3 For electrical metallic tubing

6.3.1 Couplings- one set for every length

6.3.2 Elbows- use on site bended EMT

6.3.3 Adapters w/ locknut and bushing- for every termination are 1 adapter and 1 pair of locknut and bushings.

6.4 Straps – two (2) straps for every length of conduit. In sizes of 25 mm diameter and above use clamps especially for RSC or EMT conduits.

6.5 Other fittings

6.5.1 Wire trays/cable trays – check with drawings and consultant/designer

6.5.2 Cable trough / duets – check w/ drawings especially that the drawings may have specific sizes.

7. Other Considerations

7.1 for lighting fixtures – add 1 m of wire for every termination or lighting fixtures

7.2 for convenience outlets

a. Add 0.8 m. for every C.0. to the length of pipe and 1m of wire for every termination

b. Add 0.4 m above the height of counters if the C.O. is above the counter in addition to the height of the counter. Add also 1 m of wire for every termination.

7.3 for homeruns terminating a panel boards add 2 meters of wires for every circuit.

7.4 provide an empty conduit for every spare circuit per panel

7.5 normally the electronic and communication circuits will be in separate sheets and have an ECE estimate

7.6 provide 1 connector for every termination # 6 up.

8. Summarize the lists of materials as follows

8.1 conduits – total of each size

8.2 fittings - total of each type/size

8.3 boxes - total of each type/size

8.4 panels – per panel and lowest canvassed price

8.5 Wires - total length of each wire size

8.6 Connectors – (solderless less) total termination of each size for wire #6 wire and above.

8.7 Tape – 1 roll PVC tape for every 100 m of wire plus 1 roll of rubber tape for every 200m of wire.

8.8 other materials must be itemized.

9. Costing

9.1 get the unit cost for each item and deduct all discounts.

9.2 from the total cost add 5% to 10% mark up

9.3 For all others materials like duets, panels, transfer switches, safety switches, and etc.- get the price from the fabricator net (less discounts) and add 5% markup.

10. Preparation of Bid or Asking Price

10.1 Material cost

Conduits Fitting Boxes__________________________

Wires and wiring Devices________________________

Lighting fixtures _______________________________

Safety Devices_________________________________

Service Entrance and Mains_______________________

Others________________________________________

_______________________

Subtotal A

10.2 Labor Cost

10.1 If materials are imported

a. Labor Cost is 20 % of subtotal A

b. Supervision is 3% of subtotal A

c. Mark-up is 1.25 % of subtotal A

10.2 If the conduits and most materials are locally available

a. Labor cost is 25 % to 30% of subtotal A

b. Supervision cost is 4% to 5% of subtotal A

c. Mark up cost is 2 % of subtotal A

10.3 Contingencies – an allowance of 5% to 7% of the total cost of materials and labor

10.4 Overhead – this include the cost of transportation, office staff tools and equipment depreciation, papers and office supplies to representation, and cost of money.

- Normally 7% to 10% of the cost of materials is the cost of overhead.

10.5 Permits – show the plans to the municipal electrical engineer or his assistant and request for an estimate. Add 5% to cover the exingencies.

10.6 a. the sum cost as computed in 10.1 and 10.5 is to be multiplied by 0.03 to get the contractor’s tax.

b. Add the contractor’s tax to the sum of sections 10.1 to 10.5 and round off. This will be your bid price.

3 comments:

  1. Please could u post
    1. load scheduling
    2. genset sizing
    3. cable sizing
    4. shortcircuit calculations
    5. voltage drop calculations
    6. relay, circuit breaker and fuse selection and calculations
    7. Transformer selections and sizing
    8. Earthing and Grounding
    9. capacitor bank calculations
    10. and general calculations like that ..
    please do this help for electrical designers
    thank you in advance ..

    ReplyDelete
  2. Thanks a lot! Very helpful post you got here. We're planning to build a house in a residential lot and this gave me an idea on what to prepare and estimate the total cost. We're checking on the architect on how he's gonna layout the cable tray system. Wish to read more from you. Keep on posting!

    ReplyDelete
  3. The Epc services will remain valid for 10 years . When the housing unit resold or leased within this validity period of 10 years, must be a new EPC for sale or lease made. Course must have a copy in case of rental and the original EPC in case of sale given to the new tenant or buyer.

    ReplyDelete

 
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