Electrical specifications for buildings or projects are written legal descriptions of the work to be performed by the electrical contractor, subcontractors, and electric power utilities and the responsibilities and duties of the architect/engineer, general contractor, and owner. Electrical specifications and electrical drawings are integral parts of the contract requirements for the performance of electrical work.
Because specifications are a significant part of a legally binding contract, typically involving expenditures of thousands or even millions of dollars, it is important that they be mutually compatible with the drawings and as free as possible of errors or discrepancies. It has long been known that even minor errors in wording or intent or the presentation of incorrect data or measurements can result in expensive repairs or replacements of hardware, lost time in the completion of the schedule, and serious project cost overruns due to delays and the need for additional labor and supervision.
In most engineering and architectural firms, regardless of size, specifications writers are skilled persons with technical backgrounds who report to a responsible project supervisor. The preparation of an error-free specification is a time-consuming task calling for the writer’s patience and the ability to deal effectively with complex technical details. The process might call for many drafts and revisions following the review, comments, and corrections made by persons within the architect/engineering organization with specialized knowledge and experience in each of the trades involved in the project. As with drawings, all responsible reviewers are expected to sign the final version that is released for bid.
Nevertheless, this does not relieve specifications writers of their responsibilities, because they are expected to have sufficient knowledge of the project to make them capable of finding and resolving any discrepancies between the specifications and the drawings. Discrepancies are most likely to occur when :
- A generic master or prototype specification is used without making all of the modifications necessary to reflect what is actually shown on the working drawings.
- Revisions that should have been made in a previously prepared drawings are indicated only by a note in the revision block, leaving the drawing unchanged.
- Revisions in items that are listed both in schedules on the drawings and in the written specifications are made on only one of these documents.
For example, there is a discrepancy if the specification calls for one loadcenter but the drawing has been revised to show two loadcenters and this change is not reflected back to the specifications. Such a discrepancy could result in unnecessary costs, unless caught in time. For this reason, it is not good professional practice to duplicate the same information on both specifications and drawings. It is preferable that the required information be placed on the document on which it is most logically found to assure compliance, with perhaps a reference to its location on the other document.
If for some reason duplication of information occurs in both drawings and specifications, and it is not practical to delete it from one of the documents, the project supervisor should add a note to the contract before it is put out for bid stating whether the specifications or drawings take precedence.
THE MASTER ELECTRICAL SPECIFICATION
A master Electrical specifications , regardless of its source, is a generic prototype or template that functions both as a check-off list and repository of useful paragraphs from which a specifications writer can pick and choose to prepare a working specification. Those paragraphs that do not relate to the project can be deleted and new or revised paragraphs can be added.
The master specification is written in a quasi-legal style with words such as shall, will, and may having very specific meanings. Shall, for example, indicates that the party named must carry out the specified activity; will indicates that there is certainty that the party named will perform the specified action; and may means that permission can be granted for the party named to take a specific action. Some phrases widely used in specifications to convey specific meaning are or equivalent, as approved, and unless otherwise specified.
The master Electrical specifications might be the result of years of accumulated experience of an engineering or architectural firm, or it could be a document prepared by an industry-sponsored institute based on the collective experience of its members. Regardless of the specification’s origin, it is the specifications writer’s task to modify or “tailor” it to fit a specific project. After all of the applicable general paragraphs have been selected, they are supplemented with the additional information required to identify the desired materials, equipment, products, and devices, and perhaps even specify the methods or procedures required for the performance of the work.
It necessarily follows that implementing a master specification requires specialized technical knowledge in the interpretation of drawings and practical experience or training in a specific trade. Experience is also needed in knowing the optimum locations for presenting certain kinds of information, either on the drawings or in the specification.
For many straightforward projects such as modifying or updating the electrical system in a residence, small office building, or retail shop, a simple one-page specification or description of the work to be done may be sufficient to describe the scope of the work. However, it might also have one or two working drawings attached, if necessary. By contrast, large-scale commercial or industrial projects might require hundreds of pages of specifications and hundreds of working drawings.
Master Electrical specifications are also prepared for the work of other trades such as masonry, carpentry, structural steel work, plumbing, and machine or mechanical equipment installation. Each of these divisions in a general specification is organized in a manner similar to the electrical division with certain provisions and special conditions common to all. They also include paragraphs covering such topics as the type and quality of materials to be used, the equipment to be furnished, workmanship, and testing.
The general specification must deal with situations where the work of various trades overlaps or is interdependent. This calls for precise definitions of work boundaries and the responsibilities among subcontractors. It might also involve precise scheduling to minimize worker downtime in one trade while the work of another trade is performed.
Master electrical specifications are typically organized in sections such as the following. :
General Provisions sections consist of a group of considerations and regulations that apply to all sections of the division. Topics covered might include the scope of work, electrical reference symbols, codes and fees, and tests to be performed.
Basic Electrical Material and Methodssections identify type and quality of materials, equipment, and devices specified for use such as wiring and cable, conduit, boxes, cabinets,loadcenters, switches, receptacles, motors and starters, and overcurrent protective devices. They might also specify methods for installing certain kinds of equipment.
Power Generation sections cover equipment used for emergency or standby power generation that would take over essential electrical service during a utility power outage.
They usually include installation requirements for emergency circuits, generator sets, storage batteries, controls, and distribution switches.
Medium Voltage Distribution sections cover the installation of high-voltage (over-600V) transmission and distribution facilities required for large government or industrial facilities, work that would not be performed by publicly held electric utilities because it does not relate to their system operation. The equipment specified in these sections is usually rated for more than 2.4 kV, and includes substations, switchgear, transformers, rectifiers, converters, power factor-correction capacitors, and instrumentation.
Service and Distributionsections cover the distribution of power under 600 V for residential, commercial, and light industry projects including service entrances, metering, grounding, branch circuit loadcenters, and branch circuits including the size and number of conductors, wiring devices, circuit protection devices, and installation methods.
Lighting and Luminaires sections cover interior and exterior luminaires and lamps. Schedules identify luminaire types and locations and the ratings, types, and number of required lamps. These sections cover the requirements for indoor lighting, including such topics as track and recessed lighting, emission colors of lamps, and types of ballasts. They can also cover outdoor floodlighting and even street lighting, poles, and standards.
Special Systemssections cover a wide variety of special systems related to or dependent on electrical power. Examples include lightning and surge protection, battery chargers, outdoor low-voltage lighting systems, and door chimes.
Communications sections cover such systems as fire alarm, burglar alarm, surveillance, multimedia, public address, and intercommunication, as well as wiring for telephone systems and cabling for cable and satellite TV systems.
Heating, Ventilation, and Air Conditioning sections cover the installation and wiring of electric heating, ventilating, and air-conditioning equipment. Examples include ranges, microwave ovens, washing machines, dryers, baseboard heaters, exhaust fans, and wallmounted air-conditioning units. The work of these sections requires cooperation between mechanical equipment and appliance installers and the electrical contractor.
Controls sections cover controls and instrumentation installed on a project. Examples include recording and indicating devices, interior low-voltage lighting control systems, thermostats, and remote HVAC controls.