effective electrical

7/27/2019 Effective Electrical

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NEMA Publication

The Strengths of an Effective Electrical Safety System

Published by:

National Electrical Manufacturers Association

1300 North 17th Street, Suite 1847

Rosslyn, Virginia 22209

www.nema.org

Copyright 2004 by the National Electrical Manufacturers Association. All rights including translation intoother languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protectionof Literary and Artistic Works, and the International and Pan American Copyright Conventions.


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The Strengths of an Effective Electrical Safety System

Overview

We often take electrical safety for granted. Over the past 100 years, the electrical

community has done a tremendous job reducing injuries and loss of life due to electricalshock and reducing property loss from electrically related fires. However, a good record

of accomplishment can make us complacent. It is easy to forget that this was

accomplished through ongoing improvements in electrical safety based on a robust and

cohesive electrical safety system.

Electrical safety comes at a price, and there is constant pressure to relax certain of thesafety aspects for perceived operational and economic benefits. We see examples such asthe large industrial user that considers the presence of experienced supervisory personnel

as a means to justify the relaxation of objective enforcement or prescriptive rules.

Industry experience continues to show that electricity can be dangerous in bothsupervised and unsupervised areas. With changes in building ownership and the

increasing trend toward outsourcing of labor and engineering, how can one rely onclaimed familiarity with the systems as justification to relax the rules?

The objective of this document is to provide commentary on the key elements of ourelectrical safety system and how they are connected and to also remind everyone that this

achievement in electrical safety was not an accident, but a result of 100 years of extensivework and system development.

The System

An effective electrical safety system has three distinct, but interconnected components.

Shown below is a graphic illustration of the system:

Installation

Code

ProductStandards and

Certification

Review and

Enforcement

Safe Products

and Safe

Installations

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Each portion of the system has to be capable of meeting the diverse needs of thesegments of the electrical community. The segments of concern include users,

consumers, electrical contractors (designers/installers), electrical inspectors, testing

laboratories, manufacturers, electrical workers (maintenance), and insurers.

The system has to represent a consensus among the various segments. Not all segments

will be satisfied with all elements of the system. A better level of overall acceptance and

safety can be achieved by using a consensus-based approach that draws upon theexpertise offered by each of the concerned segments.

In order to be effective, each of the three system elements must have the following keyfeatures.

Installation Codes

The installation code is the key driver for the system. It provides the fundamental safety

principles and installation rules that will provide a safe electrical system. The followingkey elements must be included in an installation code.

Compatibility with Product Standards

Although installation code rules are generally the driver, the development of those rules

must take into account the standards requirements for products contemplated to be

installed in the system. The installation code and the product standard must becompatible. This compatibility ensures that products support the safety objectives and

are used and installed in a manner as contemplated by the manufacturer.

It is erroneous to assume that one can simply select an electrical product built to any

standard and safely install it in any system. Electrical code rules are written with theexpectation that products comply with established requirements that are compatible with

the code. Improper or vague code rules increase the potential for misapplication of

products and the installation of incompatible system components that can lead to

increased hazards for persons and property.

Enforceable Prescriptive Language

An installation code must be written in enforceable language with rules that clearly set

out the installation parameters for a product. One key to standardization is to haveeveryone working from the same basic level of safety. Enforceable rules must be able to

be measurable and are often necessarily prescriptive. Without this basic prescriptivelevel, the benefits to standardization (both economical and safety related) are lost.

For years, there has been discussion of a performance-based or objective-based

approach to codes. A performance-based approach makes sense for some areas ofbuilding design. Design of fire protection systems is a good example. There are

sophisticated models for determining the required level of protection for various fire

scenarios and use of these models can help establish the system design. However, this

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type of approach does not work for determining the basic levels of electrical safety.

Conductors have to be protected, disconnects have to be readily available and workingspace must be provided. These cannot be modeled; they are fundamental safety

principles that manifest themselves in rules based on extensive experience.

In addition, electrical codes have already embraced a performance design where it maybe appropriate. This can best be shown by using an example from the National Electrical

Code. NEC 310.15 recognizes a methodology for determining the ampacity of a

conductor using the Nehr-McGrath formulas. A designer can certainly use this todetermine the ampacity of a conductor in a specific application. However, that conductor

has to terminate in some type of electrical device. The terminations on this device are

designed to operate at a maximum temperature. This maximum temperature isestablished by the product standards and covers many parameters that must be considered

in product design. The relationship to the product standard is critical since this is an

element that cannot be modeled in the field. Selection of a conductor that is too smallresults in overheating of the device terminations. In order to avoid this problem, there are

specific prescriptive rules that establish the minimums for the conductor sizing that areconsistent with the design of the product.

Product Standards and Certification

Product standards establish the minimum level of safety and associated reliability for a

product. Key areas for an effective product standard are as follows:

Compatibility with the Installation Code

Like an electrical code, product standards cannot exist in a vacuum. Product standards

must be directly compatible with the electrical installation code that covers electrical

products used in the electrical system. In order to properly test and certify a productthere have to be established ground rules for the installation of the product. These

ground rules are set forth in the form of an electrical code as outlined above.

Active Development Process

Product standards need to be developed with wide input and review from various

electrical community segments. It is also critical that there not be multiple conflictingproduct standards. The best way to accomplish this objective is to process standards

through a nationally recognized process that provides for wide participation of the

electrical community. This wide review ensures that the product standard reflects thelevel of safety and the necessary infrastructure compatibility for the system within the

defined scope of the standard. Designers, installers, or other users should not make themistake of assuming that they can select a product built to any standard and expect that

product to perform safely within their defined system. It is the formal review andadoption for the standards that establish them as the minimum requirements in a country.

Despite their appearance and traditional use, standards are not purely technical. Theyreflect social objectives. They articulate what a society agrees are acceptable levels of

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risk.1

This is one reason for striving for balanced membership on standards making

bodies. One example of the society driving product standards requirements can be foundin the area of warnings and cautions used to prevent foreseeable accidents. These are a

large part of many product standards. In societies where tort law reaches into standards

writing, these considerations are paramount.

Support of Consistent Certification

Regardless of the method of certification used, product standards must be written in a

manner that allows for consistent interpretation and enforcement. Inadequate testingprotocols and vague language can lead to inconsistent application and could result in

missing key safety elements of a product.

Furthermore, it is critical to avoid having multiple product standards that cover the sameproduct differently within a given safety system. Multiple standards lead to inefficiencies

for the manufacturer, installer, inspector and user.

Review and Enforcement

Most often overlooked in an effective safety system is the need to have an efficient and

effective system of enforcement for compliance. Having solid electrical inspection

programs that utilize qualified inspectors provides the needed controls for the system.There is a growing concern associated with the quality assurance based inspection

approach. These systems rely on review of the plans and limited auditing in lieu of

thorough and timely on-site inspections throughout the course of the construction. Themajority of the electrical community welcomes a system of inspections that provides

needed checks and balances. By contrast, taking a quality assurance approach only

serves to keep the revenue from permit fees flowing without adding any value.

Summary

Electrical safety is not an accident. Each component (codes, productstandards/certification and enforcement) is interconnected and must be coordinated to

achieve the expected level of electrical safety. History has proven that a system

containing all of these elements works very well. The electrical community should resistpressures to relax the uniform application of the safety system.

1 The Role of Standards and Market-Driven Solutions: A Canadian Perspective - by Pat Keindel. Vol.56,

No.1, Jan/Feb 2004, Standards Engineering, The Journal of the Standards Engineering Society.

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