Electrical Estimating Methods E-Book

Wayne J. Del Pico

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: RSMeans
• Sprache: Englisch

Seitenzahl: 488

Veröffentlichungsjahr: 2014

Beschreibung

Simplify the estimating process with the latest data, materials, and practices

Electrical Estimating Methods, Fourth Edition is a comprehensive guide to estimating electrical costs, with data provided by leading construction database RS Means. The book covers the materials and processes encountered by the modern contractor, and provides all the information professionals need to make the most precise estimate. The fourth edition has been updated to reflect the changing materials, techniques, and practices in the field, and provides the most recent Means cost data available. The complexity of electrical systems can make accurate estimation difficult, but this guide contains all the necessary information in one place.

An electrical estimate represents the total cost for materials, labor, overhead and profit, but accuracy is virtually impossible without a basic knowledge of the field, and real-world experience in the type of work required. Inaccurate estimates lead to problems with customer satisfaction, which often create payment issues. A thorough, complete, and accurate estimate is in the best interest of all parties involved in the work. Electrical Estimating Methods provides more than just data. Detailed discussions about the work itself help highlight factors that may escape notice, and access to the latest cost data helps tie everything together. Features include:

• Discussion of current equipment, materials, and processes
• Means data for both residential and commercial projects
• Case studies that illustrate best practices
• Online access to the latest Means data for fast access on the job

The book discusses specific situations as well as general practices, and provides comprehensive guidance to the creation of a true, current, estimation of costs. For electrical contractors and estimators, Electrical Estimating Methods contains must-have content that simplifies the estimating process.

Leseprobe

Electrical Estimating Methods

Fourth Edition

WAYNE J. DEL PICO, CPE

Cover design: Wiley Electrical box Image: © knowlesgallery/Thinkstock | Electrical blueprint image: © OLJensa/Thinkstock; Circuit diagram Image: © Monkey Business Images/ Thinkstock | Worker Image: © Ingram Publishing/Thinkstock

This book is printed on acid-free paper.

Copyright © 2015 by John Wiley & Sons, Inc. All rights reserved

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Library of Congress Cataloging-in-Publication Data:

Del Pico, Wayne J.   [Means electrical estimating methods]   Electrical estimating methods / Wayne J. Del Pico. — Fourth edition.     pages cm   Original ed. published under title: Means electrical estimating methods. c1995.   Includes index.   ISBN 978-1-118-76698-9 (paperback); ISBN 978-1-118-76684-2 (ebk.); ISBN 978-1-118-76696-5 (ebk.)   1. Electrical engineering—Estimates. I. R.S. Means Company. II. Title.   TK435.M428 2014   621.319′24029—dc23

2014018376

Dedicated to the memory of

Sid Numerof

1929–2013

Good friend, valued coworker, and dedicated family man

Contents

About the Author

PART 1 THE ESTIMATING PROCESS

CHAPTER 1 Components of an Estimate

CHAPTER 2 Types of Estimates

ORDER OF MAGNITUDE ESTIMATES

SQUARE FOOT ESTIMATES

ASSEMBLIES ESTIMATES

UNIT PRICE ESTIMATES

CHAPTER 3 Before Starting the Estimate

OBTAINING BID DOCUMENTS

TO BID OR NOT TO BID

DOCUMENT STUDY

ESTIMATING TEAM MEETING

CHAPTER 4 The Quantity Takeoff

BEGINNING THE QUANTITY TAKEOFF

RULES TO FOLLOW FOR ACCURATE TAKEOFFS

ACCOUNTING FOR WASTE

OTHER FACTORS THAT AFFECT QUANTITIES

CHAPTER 5 Pricing the Estimate

SOURCES OF COST DATA

COST CATEGORIES

TYPES OF COSTS

PROFIT

CHAPTER 6 Direct Costs

MATERIAL

LABOR

EQUIPMENT

SUBCONTRACTORS

PROJECT OVERHEAD

BONDS

CHAPTER 7 Indirect Costs

HOME OFFICE OVERHEAD

PROFIT AND CONTINGENCIES

CHAPTER 8 The Unit Price, Project Overhead Summary, and Estimate Summary Sheets

UNIT PRICE SHEET

PROJECT OVERHEAD SUMMARY SHEET

THE ESTIMATE SUMMARY SHEET

CHAPTER 9 Prebid Scheduling

SCHEDULING THEORY

CRITICAL PATH METHOD (CPM)

VALUE OF THE PREBID SCHEDULE

TASK TYPES

TASK DURATIONS

CALCULATING DURATIONS

MILESTONES AND CONSTRAINTS

CHAPTER 10 Bidding Strategies

THE BUSINESS PLAN

COMPETITIVE BIDDING

RESOURCE ANALYSIS

MARKET ANALYSIS

GENERAL BIDDING STRATEGIES

MAXIMIZING THE PROFIT-TO-VOLUME RATIO

CHAPTER 11 Project Cost Control and Analysis

COST CONTROL

PRODUCTIVITY AND EFFICIENCY

OVERTIME IMPACT

PART 2 COMPONENTS OF ELECTRICAL SYSTEMS

CHAPTER 12 Raceways

CABLE TRAY

CONDUIT (TO 15′ HIGH)

CONDUIT FITTINGS

CONDUIT IN CONCRETE SLAB

CONDUIT IN TRENCH

CUTTING AND DRILLING

WIRE DUCT—PLASTIC

TRENCH DUCT

UNDERFLOOR DUCT

SURFACE METAL RACEWAYS

WIREWAYS

FLEXIBLE METALLIC CONDUIT

CHAPTER 13 Conductors and Grounding

WIRE

ARMORED CABLE

CABLE TERMINATIONS (TO 600 VOLT)

SHIELDED POWER CABLES

CABLE TERMINATIONS (HIGH VOLTAGE)

MINERAL INSULATED CABLE

NONMETALLIC SHEATHED CABLE

FIBER-OPTIC CABLE SYSTEMS

SPECIAL WIRES

GROUNDING

UNDERCARPET WIRING

UNDERCARPET TELEPHONE SYSTEMS

UNDERCARPET DATA SYSTEMS

CHAPTER 14 Boxes and Wiring Devices

PULL BOXES AND CABINETS

OUTLET BOXES

WIRING DEVICES AND LOW-VOLTAGE SWITCHING

FASTENERS

HANGERS

CHAPTER 15 Starters, Boards, and Switches

CIRCUIT BREAKERS

CONTROL STATIONS

FUSES

LOAD CENTERS

METER CENTERS AND SOCKETS

MOTOR CONTROL CENTER

MOTOR CONTROL CENTER COMPONENTS

MOTOR CONNECTIONS

MOTORS

MOTOR STARTERS AND CONTROLS

CONTACTORS

RELAYS

PANELBOARDS

PANELBOARD CIRCUIT BREAKERS

SAFETY SWITCHES

SWITCHBOARDS

SUBSTATIONS

CONTROL SWITCHES

CHAPTER 16 Transformers and Bus Duct

TRANSFORMERS

ISOLATING PANELS

BUS DUCT

BUS DUCT/BUSWAY—100A AND LESS

UNINTERRUPTIBLE POWER SUPPLY SYSTEMS

CHAPTER 17 Power Systems and Capacitors

CAPACITORS

GENERATOR SET

AUTOMATIC AND MANUAL TRANSFER SWITCHES

CHAPTER 18 Lighting

INTERIOR LIGHTING FIXTURES

EXIT AND EMERGENCY LIGHTING

EXTERIOR FIXTURES

LAMPS

TRACK LIGHTING

FIXTURE WHIPS

CHAPTER 19 Electrical Utilities

ELECTRIC SITE WORK

CHAPTER 20 Special Systems

SPECIAL SYSTEMS

CLOCK SYSTEMS

DETECTION SYSTEMS

DOORBELL SYSTEMS

ELECTRIC HEATING

LIGHTNING PROTECTION

NURSES’ CALL SYSTEMS

CLOSED-CIRCUIT TV SYSTEMS

RESIDENTIAL WIRING

CHAPTER 21 Electrical Demolition and Temporary Facilities

DEFINING THE ELECTRICAL DEMOLITION SCOPE

ELECTRICAL DEMOLITION

TEMPORARY FACILITIES

CHAPTER 22 Contract Modifications

CONTRACT MODIFICATIONS

WHAT MAKES CHANGE ORDERS DIFFERENT

EFFECTS OF OVERTIME

CHAPTER 23 Project Closeout

THE CLOSEOUT PROCESS

OBJECTIVES OF THE CLOSEOUT PROCESS

CONTRACT CLOSEOUT

ADMINISTRATIVE CLOSEOUT

LESSONS LEARNED

CHAPTER 24 Computerized Estimating

BASIC SPREADSHEET PROGRAMS

STAND-ALONE ESTIMATING SOFTWARE

QUANTITY TAKEOFF SOFTWARE

APPENDIX: Symbols and Abbreviations

TRADE SPECIFIC SYMBOLS

Index

End User License Agreement

List of Tables

Chapter 2

Table 2.1

Table 2.2

Table 2.3

Chapter 6

Table 6.1

Chapter 8

Table 8.1

Table 8.2

Table 8.3

Table 8.4

Chapter 10

Table 10.1

Table 10.2

Chapter 11

Table 11.1

Chapter 12

Table 12.1

Table 12.2

Chapter 13

Table 13.1

Table 13.2

Table 13.3

Table 13.4

Table 13.5

Chapter 15

Table 15.1

Table 15.2

Table 15.3

Table 15.4

Table 15.5

Table 15.6

Table 15.7

Table 15.8

Chapter 16

Table 16.1

Chapter 18

Table 18.1

Table 18.2

Table 18.3

Table 18.4

Table 18.5

Chapter 20

Table 20.1

Chapter 22

Table 22.1

Chapter 24

Table 24.1

List of Illustrations

Chapter 12

Figure 12.1

Cable Tray System

Figure 12.2

Installation Time in Labor-Hours for Cellular Concrete Floor Raceway System

Figure 12.3

Underfloor Raceway System

Chapter 13

Figure 13.1

Installation Time in Labor-Hours for Undercarpet Telephone Systems.

Figure 13.2

Installation Time in Labor-Hours for Undercarpet Data Systems.

Chapter 14

Figure 14.1

Installation Time in Labor-Hours for NEMA Enclosures

Figure 14.2

Installation Time in Labor-Hours for Wiring Devices

Chapter 15

Figure 15.1

Installation Time in Labor-Hours for Metering Switchboards

Figure 15.2

Installation Time in Labor-Hours for Motor Control Centers

Chapter 20

Figure 20.1

Installation Time in Labor-hours for Clock Systems.

Figure 20.2

Installation Time in Labor-Hours for Lightning Protection.

Figure 20.3

Installation Time in Labor-Hours for Nurses’ Call Systems.

Guide

Cover

Table of Contents

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About the Author

Wayne J. Del Pico is president of W. J. Del Pico, Inc., where he provides construction management and litigation support services for construction related matters. He has more than 35 years of experience in construction project management and estimating and has been involved in projects throughout most of the United States. His professional experience includes private commercial construction, public construction, retail construction, and residential land development and construction.

Mr. Del Pico holds a degree in civil engineering from Northeastern University in Boston, where he taught construction-related curriculum in Cost Estimating, Project Management, and Project Scheduling from 1992 until 2006. He is also a member of the adjunct faculty at Wentworth Institute of Technology in Boston, where he presently teaches programs in Construction Cost Analysis, Estimating, Project Control, and Construction Scheduling.

Mr. Del Pico is a seminar presenter for the RSMeans Company, where he provides instruction on topics from estimating to scheduling. He is the author of Plan Reading and Material Takeoff (1994), Estimating Building Costs (2004) and its second edition in 2012, and is a co-author of The Practice of Cost Segregation Analysis (2005). His most recent book, Project Control: Integrating Cost and Schedule in Construction, was published by Wiley in September 2013.

His construction experience and knowledge of the industry has qualified him to be the past president of the Builders Association of Greater Boston (2010). He is also a practicing Neutral for the American Arbitration Association, where he hears construction-related arbitration cases.

To learn more about the author, visit www.wjdelpico.com.

1THE ESTIMATING PROCESS

CHAPTER 1Components of an Estimate

One of the most difficult tasks in estimating any project is to capture all of the costs involved in the project. Construction has many variables, and it is these variables that can have an impact of the way the estimator “sees” the work and ultimately its costs. The means and methods selected, or the plan to execute the work, will impact price significantly. Another important variable is the bid documents; comprehensive, fully developed designs offer a better chance for the estimator to reach an accurate price. It is the goal of the estimator to arrive at the most accurate price for the cost of the work under a specific set of circumstances and conditions.

While different estimators may see a project differently and thereby arrive at a different price for the work, all estimates share some basic components. Every cost estimate requires three basic components. The first is the establishment of standard units of measure. The second component of an estimate is the determination of the quantity of units for each component, which is an actual measurement process: how many linear feet of wire, how many device boxes, and so on. The third component, and perhaps the most difficult to obtain, is the determination of a reasonable cost for each unit.

The first element, the designation of measurement units, is the step that determines and defines the level of detail, and thus the degree of accuracy, of a cost estimate. In electrical construction, such units could be as all-encompassing as the number of watts per square foot of floor area or as detailed as a linear foot of wire. Depending on the estimator's intended use, the designation of the unit of measure may describe a complete system, or it may be a single task within the entire scope of the project. The selection of the unit of measure also determines the time required to do the estimate.

The second component of every estimate, the determination of quantity, is more than simply counting units. In construction, this process is called the quantity takeoff or quantity survey. It is an integral part of the estimating process that requires an intimate understanding of the work being estimated and a commitment to accuracy. To perform this function successfully, the estimator should have a working knowledge of the materials, methods, and codes used in electrical construction. An understanding of the technical specifications that were the basis of the design is also particularly important. This knowledge helps to ensure that each quantity is correctly tabulated and that essential items are not forgotten or omitted. The estimator with a thorough knowledge of construction is also more likely to account for all requirements in the estimate.

A clear understanding of the scope, or limits of the work, what is included and what is not, is also critical for a defining the estimate.

Not all of the tasks in an estimate involve materials; some are labor-only tasks. Testing is an example of a labor-only item. Some can be just material items, for example, a work box and conduit that is set in a masonry wall by the bricklayer. Experience is, therefore, invaluable to ensure a complete estimate.

The third component is the determination of a reasonable cost for each unit referred to as pricing. This aspect of the estimate is significantly responsible for variations in estimating. Rarely do two estimators arrive at exactly the same material cost for a project. Even if material costs for an installation are the same for competing contractors, the labor costs for installing that material can vary considerably, as a result of varying productivity and pay scales in different areas. The use of specialized equipment can decrease installation time and, therefore, cost. Finally, material prices fluctuate within the market. These cost differences occur from city to city and even from supplier to supplier in the same town. It is the experienced and well-prepared estimator who can keep track of these variations and fluctuations and use them to his or her best advantage when preparing accurate estimates.

This third phase of estimating, the determination of costs, can be defined in three different ways by the estimator. With one approach, the estimator uses a unit cost that includes all the elements (i.e., material, installation, overhead, and profit) in one number expressed in dollars per unit of work. A variation of this approach is to use a unit cost that includes total material and installation as a single amount, adding a percent markup for overhead and profit in the estimate summary.

A second method is to use individual unit costs for material and for installation. Costs are calculated separately for each category without markups. These are called bare costs. Different profit and overhead markups are applied to each item before the material and installation prices are totaled. The result is called the billing rate or price.

A third method of pricing uses unit costs for materials, with labor-hours as the measure of labor. Again, these figures are totaled separately; one represents the value of materials expressed in dollars, and the other shows the total labor-hours for installation. The average cost per hour of trade labor is determined by allowing for the expected ratios of foremen, journeymen, and apprentices. This is sometimes called a composite labor rate. This rate is multiplied by the total labor-hours to get the total bare cost of installation. Different overhead and profit markups can then be applied to each, material and labor, and the results added to get the total billing rate.

Whichever methodology is selected, it is important to remember that it should remain consistent through the entire estimate to avoid errors, omissions, or duplications. The estimator must, therefore, exercise care to utilize these methods correctly and consistently for the format of each particular estimate.

As a point of clarification, the word unit is used in many ways, as can be seen in the preceding definitions. Keeping the concepts of units clearly defined is vital to achieving an accurate, professional estimate. For the purposes of this book, the following references to different types of units are used:

Unit of measure.

The standard by which the quantities are counted, such as

linear feet

of conduit, or

number

of boxes. There are industry-accepted standards of units for almost all work.

Cost units.

The total dollar price per each installed unit of measure, including the costs of material and installation. This figure may be a bare cost or may include overhead and profit.

Material unit cost.

The cost to purchase each unit of measure. This cost represents material dollars only—with no overhead and profit.

Installation unit cost.

The cost for installing each unit of measure. This cost includes labor dollars only—with no overhead and profit.

Labor unit.

The labor-hours required to install a unit of measure. (

Note:

Labor units multiplied by the labor rate per hour equals the installation unit cost in dollars.)

A final thought on cost: It is important to note that the word cost is defined by its frame of reference. For the general contractor; the electrical contractor's entire price is a cost. When the work is complete, the general contractor will pay the entire contract amount to the electrical contractor and record it as a cost to the project. For the electrical contractor, cost is defined as all amounts in the estimate, with the exception of the profit. The electrical contractor will records costs as material, labor, and equipment paid to others, while the profit made is the only item not classified as a cost.

CHAPTER 2Types of Estimates

Estimators use four basic types of estimates. These types may be referred to by different names and may not be recognized by all as definitive. Most estimators, however, will agree that each type has its place in the construction estimating process. The four types of estimates are as follows:

Order of magnitude estimate.

The order of magnitude estimate could be loosely described as an educated guess. It can be completed quickly. Accuracy will vary between 20% and 25%.

Square foot estimate.

This type is most often useful when only the proposed size and use of a planned building is known. This method can be completed within an hour or two. Accuracy can be plus or minus 15%.

Assemblies estimate.

A systems estimate is best used as a budgetary tool in the planning stages of a project when some parameters have been decided. This type of estimate could require as much as one day to complete. Accuracy is expected to be plus or minus 10%.

Unit price estimate.

Working drawings and full specifications are required to complete a unit price estimate. It is the most accurate of the four types but is also the most time consuming. Used primarily for bidding purposes, the accuracy of a unit price estimate can be plus or minus 5%.