From "Della" <della@acmgfcu.net>
To: <joetede@ix.netcom.com>

I work in a factory with printing presses and other machines that take printed
cartons and fold and glue them to be sent to other companies who package things like powdered laundry detergent and clumping cat litter in them.

We use mainly EMT and not rigid conduit.

My questions are:

1) Should we pull in equipment grounding wires for the electrical outlet receptacles and lighting (120 volt and 277 volt) instead of relying on the tubing for equipment grounding?

YES


2) Is it okay to replace double insulated tool plugs with 3 prong plugs, although there is no ground wire attached to that plug, or is it necessary to replace them with 2 prong plugs?

NO, USE SAME

3) Is it necessary to bond peices of machinery that have no mechanical connection between, them but are connected through conduit and part of the same system?

YES, TO PREVENT STATIC ELECTRICITY

(example is for equipment that feeds the paper web to the printing presses and rerolls it as it comes off)

Thanks for any help you can give me in these matters.

Joe,

I wish that more Q's from people [or Clients] were as simple to answer as these were!!!

Glad that you agree on #1 to include a supplimental EGC - even if the raceway is metallic!!! That's a point I'm personally trying to push, since once the conduit is separated by a broken coupling, the EGC is lossed - including a bonding conductor makes everything a bit more safe [not completely foolproof, though!!].
This is from the countless numbers of times I have seen EMT damaged at couplings, with one Ungrounded conductor being wedged against the "Load" side of the broken coupling - resulting in conduit[s] being a shock hazard to ground.

On #2, using a 3 wire [grounding] cord cap would have any metallic parts of the cord cap [i.e. Plug] connected to the EGC/grounding pin. In that case, there's once again a ground fault hazard to personnel which will not be tripping any OCPD, but would trip a GFCI after a person was being shocked! [only if GFCI was operating properly].

#3 - Major static [ESD] potential on a paper mill!! Even if the machinery wasn't that purpose, the solid ground bonding assures that all assemblies are as close to the same potential as possible.

Just wanted to add some stuff to your post, mainly so others can see where you are basing ideas from, along with showing a common interest from two or more members on the subjects.

Thanks for the post!!!

P.S. can you contact me soon in regards to the Instructor position??? Can't do it now, but maybe by October I'll have ample time for it.

Scott SET

While doing some periodic testing today I looked around the room and saw two EMT tubes that had become seperated. Luckily all of the pipes in the building have a grounding conductor run in them.

I am all for running a grounding conductor in conduit.

Scott:

The answers I gave, which were my personal opinions, were based upon some of my own personal experiences, and help to support Mike's comment.



[This message has been edited by Joe Tedesco (edited 07-07-2001).]