Technical information

Industrial Machinery

1. NEC 2005 and article 670 on Industrial Machinery

In September 1941 the metal working machinery industry elaborated its first

electrical standard to make machinery safer for operators, more productive and

cheaper to maintain, as well as to improve quality and performance of electrical

components.

In the same year and in order to analyse electrical problems related to machinery,

the NFPA created a special electrical commission specialised in overcurrent

protection and the control of industrial engines fitted to industrial machinery.

This commission, in collaboration with the manufacturers of machinery electrical

equipment and Underwriters Laboratories, carried out a series of test and controls

whose results differed with the requirements of the National Electrical Codes at

that time.

The results were published in 1942 as an “amendment” to article 670 on Machine

Tools of the National Electrical Code of 1940 and such article remained basically

unchanged until the 1959 edition appeared.

Mistakenly, in 1940 other machinery manufacturers started to take article 670 as a

reference when it had been initially drawn up exclusively for metal working

machinery.

Then, in 1952, an electrical commission was established to try to gather all the

special requirements for the production, handling and process machinery all in

one NEC article.

This attempt failed and in 1956 a NFPA commission was established to limit the

application of art. 670 NEC only to metal working machinery. This article

remained however too limited; and it was so because a new standard that

specified safety requirements not dealt with before was included.

In 1961 the NFPA 79 “Electrical Standards for machine tools” was officially

introduced and subsequently revised in 1965, confirmed in 1969 and revised

again in 1970, 1971, 1973, 1974, 1977, 1980, 1985, 1987, 1989, 1994 and the last

edition in 2002 which is currently in force.

In fact in its first clauses, the National Electrical refers to NFPA 79 as the reference

standard applicable to industrial machinery.

NFPA 79 Industrial Machinery refers to the UL508A standard on Industrial Control

Panels as the primary reference standard, and so circle is completed as per North

American legislation on electrical systems for industrial machinery:

INDUSTRIAL MACHINERY

NEC Art. 670

Industrial Machinery

(Codice d’installazione)

NFPA79

Electrical Standard for

Industrial Machinery

UL508A

Industrial Control

Panels