Wednesday, May 6, 2015

Inspection of Industrial Establishments

Readers who can’t follow Malayalam language may please excuse me for the video clip below, featuring an electrical inspection of a proposed biscuit factory. This hilarious film that also exposed the pathetic industrial atmosphere prevailing in Kerala was a big box office hit and the message is relevant even today. This clip is from the film, ‘Mithunam’, released in 1993, featuring actor Mohanlal in the lead role of an entrepreneur whose plans are thwarted by bureaucracy bent on extorting bribes and other pecuniary benefits. The portion shown in the clip narrates the inspection of the factory by an electrical engineer of the distribution company, prior to energization. The technical points raised by the inspector and the reply are given below. The supply is low-tension, as gathered from an earlier scene in which the engineer asks the entrepreneur to subscribe to an insurance policy of Rs. 1 Lakh (in 1993!) to increase the rated capacity of the local transformer.

(Inspector enters the factory premises)

Inspector: “Where is the diagram of the electrical circuit?”
Entrepreneur: (hesitates) “diagram….diagram….diagram is there, sir” (pointing to some other place)
Inspector: “Which are the cables used? Aren’t they armoured?”
Entrepreneur: (silent)
Inspector: (looking at the main isolator) “Where is the ISI mark? It is mandatory”
Entrepreneur: “Sir, sir, best switches from Delhi are used sir..”
Inspector: (looking at a machine) “What? The same connection for lighting and machine? Don’t you know that it should not be done?”
Entrepreneur: (folding his hands) “Sir…sir…”
Inspector: (irritated) “No, I am not satisfied. All this wiring should be changed”

(The inspector then starts moving out of the factory, at which time, the entrepreneur’s elder brother, who had a personal vendetta against the inspector intervenes and slaps him on the face asking to sign without raising unnecessary objections. He runs for his life and the scene ends here)

I first saw this movie immediately after graduation. At that time itself, I wondered whether the objections raised by the inspector are indeed valid and legal, even though the film portrays him as a venal official readily accepting bribes. Four points are involved in this issue.

a)    Armoured cables shall be used in industrial installations
b)    Electrical circuit diagram shall be readily available in an installation
c)    Lighting and power circuits shall be separated
d)    Switches conforming to BIS standards shall be used

Practicing electrical engineers know that all these points are strictly adhered to, in any industrial installation. But many people are confused as to where these conditions appear in statutes. So I made a little research on the standards and other rules to find out the primary source, from where these regulations have emerged as standard practice.

Two documents that act as guide for electrical installations in India are,

a)    IS 732: 1989, Code of Practice for Electrical Wiring Installations
b)    SP 30: 2011, National Electrical Code (NEC) 2011

It may be noted that these documents will be amended periodically and obviously, the latest amendment shall be used wherever applicable.

Now, we will see one by one as to where in these documents our four issues appear.

1. Use of armoured cables

Clause E- of IS 732:1989 states that “The circuits shall be checked whether lighting wiring in factory area is taken enclosed in conduit and conduit properly earthed, or alternatively, armoured cable wiring is used

Moreover, Clause 6.3.1 of NEC 2011 specifies that “For power distribution from a substation or main switchboard to a number of separate buildings, use shall preferably be made of armoured cables of mineral-insulated and metal-sheathed or PVC/XLPE insulated cables“.

2. Electrical circuit diagram

Clause 7.4.3 of IS 732:1989 states that
 Diagrams, charts or tables shall be provided indicating in particular:
 a)    the type and composition of circuits (points of utilization served, number and size of conductors, type of wiring ); and
b)    the information necessary for the identification of the devices performing the functions of protection, isolation and switching, and their locations.

For simple installations the foregoing information may be given in a schedule.

3. Separate switches for lighting and power circuits

Clause of IS 732:1989 stipulates that “Separate circuits shall be provided for parts of the installation which need to be separately controlled, in such a way that these circuits are not affected by failure of other circuits

4. Switches with ISI mark

Clause 7.1 of IS 732:1989 states that “Compliance with Standards - All equipment fittings and accessories, materials, etc, selected for the wiring installation shall conform to the relevant Indian Standard

Also, this is mandated by NEC as well as seen by clause 2.1, “Every item of electrical equipment used in the installation shall conform to the relevant Indian Standards, wherever available

See? Everything the engineer demanded in the above scene was valid and mandatory!


  1. Really Great Blog to implement the electrical
    Safety in the companies , Videos and the Discussion colom every thing helped me a lot to understand . Indian standards are really nice

  2. Hope so that this will help in looking beautiful for longer time.
    metering pump manufacturer in india

  3. Survey of a site is very important for setting a plant or industries over there by the electrical point of view, it must be done by an expert so that there is no chance of getting a single mistake, thanks for blogging such a great post.
    Electricians Christchurch