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Grounding Bonding Earthing... Again

4K views 19 replies 10 participants last post by  T Healy 
#1 ·
A supplier of industrial ground fault equipment sent me a booklet on grounding.
The first thing I saw, Figure 1, was ground rods driven at both the transformer secondary and the breaker panel down stream. These ground rods are connected by a grounding electrode conductor (GEC). The transformer enclosure seems to be bonded via a circuitous route through the GEC to the breaker panel enclosure and then back through the "Bonding jumper" to the transformer enclosure.


The top drawing is from the booklet.
The bottom drawing is how I think it should be.

This company deals with industrial customers and I do mostly residential but I've been on a few industrial jobs with transformer / panel setups and I've never seen the setup shown at top.
 

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#4 ·
When to install ground rods?

It looks to me like you install ground rods:

1. At utility transformer poll connected to utility transformer secondary.

2. At service between meter and main. Actually, this is where the electrode grounding conductor would be attached but you get what I mean.

3. Between secondary of separately derived system transformer and breaker panel down stream.

4. At the ground bus of a sub-panel in an secondary building. The service, in this case enters the primary building and feeders supply the sub-panel in the secondary building. Typical unattached garage, multiple circuit set-up.

Is it a violation to install ground rods at panels within the same building as shown in the equipment manufacturer's drawing at the start of this thread?
 
#10 ·
Steve, I was looking at the picture as, for example, a 480 / 208 transformer downstream of the main distribution panel. I've worked on this part of the system but never upstream of such a transformer so my knowledge of MDP is limited. I assume an MDP contains a 600A main, or something on that order, and is fed by the power company. I also assume an MDP would have a meter.

If the panel shown in the picture is an MDP then the delta-wye transformer would belong to the power company, and both the transformer and the MDP would have ground rods as shown in the top picture. Also, if this was an MDP, I'd expect to see a meter. I would not expect to see the connection labeled "System Grounding" which looks to me like a grounding electrode conductor.
 
#9 ·
At least most companies out this way are getting (or have gotten away) from installing hundreds of ground rods across a site.. Usually now only around electrical rooms, radio towers and buildings that are on a concrete pad.. Most have given up on a ground rod next to a pile for a building and burying a 2/0 loop of insulated ground wire around the outside perimeter of the building...
 
#11 ·
Well ok Swimdude,

First off the meter on most anything over 400A is CT, so don't even worry about it

Secondly, consider the poco xformer it's own entity, complete with it's own grounding requirements, not exactly the normal 480/208 deal you may be used to

Third, consider your main MDP where the premis grounding all terminates to a MBJ (main Bonding Jumper) Perhaps this is where the confusion exists, in part because of the semantical nature of art 100, now inclusive of 'Main' and 'System' bonding jumper both descriptive of an N & G bonding in different situations

Lastly, consider the return path noodle for the entire install. This is the stumper that gets even masters rattled btw, because the theory and practical application often clash

hope that helps ~CS~
 
#17 ·
'Neutral' , WAS trade slang for over a century in the NEC Brian

GroundED and GroundING conductors were considered proper terminology until recent times

The rationale the CMP forwarded was simply because enough of the trade used the slang term to enable it's officiation

So in fact, if my noodle* term had taken off from it's inception some 20 yrs ago, it might have rated CMP advocation :thumbsup:

That said, reducing any debate's underlying concept or theory to droll non sequitur semantical banter is so last Tuesday here

Again. i challenge you (et all) to rise above it





*all rights reserved by the chickenman, chickenman's hiers and the estate of chickenman

~CS~
 
#18 ·
'Neutral' , WAS trade slang for over a century in the NEC Brian

GroundED and GroundING conductors were considered proper terminology until recent times

The rationale the CMP forwarded was simply because enough of the trade used the slang term to enable it's officiation

So in fact, if my noodle* term had taken off from it's inception some 20 yrs ago, it might have rated CMP advocation :thumbsup:

That said, reducing any debate's underlying concept or theory to droll non sequitur semantical banter is so last Tuesday here
No debate here, take a license test for our trade and use the word noodle, you will be laughed out of the class room.

Steve It is in the IEEE Dictionary, find noodle anywhere in the IEEE Dictionary otherwise, case closed.

Many words that were slang become the accepted word and show up in approved dictionaries and NOODLE ain't one off them in our trade.
 
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