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Joined: Oct 2000
Posts: 2,749
Question 1: Do you design or build machine shops, and do you install industrial machinery?

Question 2: How are electricians installing these systems?

NFPA 79, Electrical Standard for Industrial Machinery 2002 Edition

Chapter 1 Administration

1.1* Scope.

1.1.1 The provisions of this standard shall apply to the
electrical/electronic equipment, apparatus, or systems of industrial machines operating from a nominal voltage of 600
volts or less, and commencing at the point of connection of
the supply to the electrical equipment of the machine.

1.1.2 This standard shall not include the additional requirements
for machines intended for use in hazardous (classified)

*Annex A Explanatory Material

Annex A is not a part of the requirements of this NFPA document
but is included for informational purposes only. This annex contains explanatory material, numbered to correspond with the applicable text paragraphs.

A.1.1 In this standard, the term electrical includes both electrical and electronic equipment. Requirements that apply only to electronic equipment are so identified.

The general terms machine and machinery as used throughout
this standard mean industrial machinery. See Annex C for
examples of industrial machines covered by this standard.

Annex C, Examples of Industrial Machines Covered by NFPA 79

This annex is not a part of the requirements of this NFPA document but is included for informational purposes only.

C.1 Machine Tools. Examples of machine tools are as follows:

(1) Metal cutting
(2) Metal forming

C.2 Plastics Machinery. Examples of plastics machinery are as

(1) Injection molding machines
(2) Extrusion machinery
(3) Blow molding machines
(4) Specialized processing machines
(5) Thermoset molding machines
(6) Size reduction equipment

C.3 Wood Machinery. Examples of wood machinery are as

(1) Woodworking machinery
(2) Laminating machinery
(3) Sawmill machines

C.4 Assembly Machines.

C.5 Material-Handling Machines. Examples of material handling
machines are as follows:

(1) Industrial robots
(2) Transfer machines
(3) Sortation machines

C.6 Inspection/Testing Machines. Examples of inspection/
testing machines are as follows:

(1) Coordinate measuring machines
(2) In-process gauging machines


Joe Tedesco, NEC Consultant
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Joined: Jan 2005
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Cat Servant
Joe, in order to properly wire a machine shop, an electrician has to go well beyond his apprentice training- and he must understand the plant's operations. There must also be plenty of HONEST communication between the plant folks and the sparky.

Simply put, considering the typically poor job archetects do in laying out a simple restaraunt, the very real complications of a production facility shold not be ignored.
As an example, I recently wired a plant with essentially a blank print- no equipment layouts, nothing. Yet, this was a customer, and a process, with which I was familiar- so I was able to "guess" right on all but two small items. Even so, I had to deal with a LOT of second-guessing and doubting Thomas's during the job; only after they moved in were they able to see that I was well "ahead of the curve."

Enough bragging, though- here's where you start: layout the equipment so machine "A" feeds machine "B". Allow plenty of room for material handling, scrap handling, and traffic. Keep in mind where the inspection tables and tool chests will be.

Lay out the lighting so that you get LOTS of light- think "bright" and double it (quadruple it if you've been doing mainly warehouses)- to the surfaces of work tables and access hatches of the equipment. Light quality is at least as important as the number of ft-candles. Directed light is fine- the aisle five feet away can be considerably darker. There is NO advantage in having everything laid out in a neat grid on your plans; far better that the light be where it's needed, and the fixture where you can get to it (to change a bulb).

You treat every machine as "continuous" to size your supply wires (feeders). Here is where you have to decide- pipe or bussways? Remember, things will get moved or replaced in time.
You will also want to plan for data drops to every machine; the days of some guy standing at the machine, with a print stuck to the cover, and his hand cranking a handle are LONG gone. Don't ignore "physical protection;" the area will see a lot of action!
Every machine back and work station will need to have a convenience receptacle. I have lost count of the times I've seen such receptacles added later, usually by tapping one of the supply legs and using the pipe as the 'neutral.' Don't set the stage for this to happen!

Don't overlook the other things that will be necessary- the air compressors, the garage door openers, the exhaust fans, etc.

Then there is the matter of power quality. It is very possible that you will be adding a capacitor bank to correct "power factor." There are also real advantages to having some means of "cushioning" spikes from the PoCo supply, be it a UPS, battery bank, even transformers. In all cases you should have protection against single-phasing.
While many of the newer machines have these features designed into them, don't rely on that. Often the air compressors will be quite basic- and compressed air is a "utility" for these machines.

Joined: Oct 2000
Posts: 2,749
Words of wisdom! So true!

Thanks for the Preface .....

Who offers training on NFPA 79 other than the NFPA?

Joe Tedesco, NEC Consultant
Joined: Aug 2005
Posts: 64
Joe, I would like more information on this topic. I'm not aware of any industrial electrical training. I work in a steel mill and we contantly have new machines being installed. When the plant was being built, we oversized everything and had a really nice layout. It has saved up many headaches so far and I'm sure it will continue to pay off. You have to protect everything from fork trucks and overhead cranes. Anything that can be smashed and destroyed, will be smashed and destroyed at some point in time if it is accessible.

Joined: Nov 2000
Posts: 2,148
Note that per the scope statement in NFPA 79, that code only applies to the machine itself. Unless the electrician is building the machine, I don't see NFPA 79 applying to electricians.

Joined: Oct 2000
Posts: 2,749
Article 670 in the NEC covers Industrial Machinery. An electrician who maintains this type of equipment is sometimes required to rebuild or replace parts in the machine. This is not very easy work and takes a lot of time and knowledge to accomplish. I have worked in a machine shop and in a shop where there were plastics and metal working machine tools. This was good experience and helped me to broaden my understanding of the electrical industry. I was the NFPA Staff Liaison for NFPA 79. Now, withe the NEW Article 409 and UL 508A, the electrician will become more involved.

Joe Tedesco, NEC Consultant
Joined: Jan 2005
Posts: 5,422
Likes: 1
Cat Servant
NFPA 79 has its' problems....indeed, the whole issue is a problem in itself.

The problem is: what is a "machine?" Typically, a number of machines will be inter-connected into a complete process. These may be separate components of the same assembly, or a mix of differing makes made to work together.

This is why understanding the process itself is essential to having a "safe" machine. It is quite possible to have a machine be both deadly dangerous, and still be code compliant. What happens when the "stop" button is pushed is one of the basic issues, often without a simple answer.

Likewise, "safety" in controls goes way beyond wire colors and component spacing. It is to the great credit of machinery designers that the stuff is as safe as it is- and these guys have generally been doing this without any codes saying they must!

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