Commercial HVAC equipment grounding

Status
Not open for further replies.
This is what I view the issue to be,...I thought the new guy made a mistake by pulling a E.G.C in the emt in the first place and there were 14 left to wire ,.. regardless the quote below represents the main issue ,.. this inspector is wrong and George should prevail

george nicholson said:
... The inspector is trying to say that the ground always has to go to the panel if there is anything but solid EMT all the way......
Click to expand...
 
1) The inspector is correct about black #8 with green marking tape --- though I feel being extreme in a heavy industrial project. Per code this is incorrect and that must be corrected and I can accept that fact.

2) The "continuous" should be stated as this--- " the ground must be a conductor running from the panel ground buss to the disconnect NOT a ground conductor mechanically connecetd to the j-box at the start of the flex. It muts be connected to the ground buss in the panel or pipe solid with no flex to the disconnect which is not possible. I say he is incorrect about this. He will NOT show proof only tells me to find the violation in the code book myself and its not there in my opinion.

3) The voltage drop is not an issue we are only 90' to 150' from the panel and wire is actually 1 size larger than required but protected correctly. This place was LEED certified and has multiple work zones on IR and thermostats thus many small units. I would just do it but the j-boxes are approx 26' up and the tenant has moved large racking into the space and j-boxes must now be accessed with extension ladders and walk boards.

4) Again he wants a #10 green starting at ground bus in panel to disconnect on unit and tells me to find code that says I can not start the ground in the j-box. He will not show it to me as its not there in my opinion.
 
So you can pull out the #8 and use the EMT as an EGC from the panel to the box. Then you need to install a properly sized EGC within the flex from the box to the unit. It's that simple.
 
Explain to his boss ,.that ,.not only can you not find where it is prohibited ,you have found that 250 .118 supports your solution ,...to the very serious tape violation,.. exactly ..

You may also want to remind his boss that it is the responsibility of the inspector to note what article has been violated.

I know it easier said than done ,.. but I hope you fight this little monster .

Good luck.



http://images.google.com/imgres?img...n&safe=off&rls=GGLG,GGLG:2007-39,GGLG:en&sa=G
 
Dennis Alwon said:
Let me put a wrench in the works--- did you read art. 250.122(B) and see if that affects you. I believe it will.
Click to expand...


IF the ungrounded conductors have been increased in size. I don't remember anywhere in the thread that says they have been.
 
480sparky said:
IF the ungrounded conductors have been increased in size. I don't remember anywhere in the thread that says they have been.
Click to expand...

How about here. The post before my response

3) The voltage drop is not an issue we are only 90' to 150' from the panel and wire is actually 1 size larger than required but protected correctly.
Click to expand...
 
Dennis Alwon said:
Yes, however the op still would need a #8 thru the nonmetallic flex from the JB.
Click to expand...


From Mike Holt ,..I thought I would just post an example for informational purposes

[FONT=Arial, Helvetica, sans-serif]
[FONT=Arial, Helvetica, sans-serif]If you increase the size the ungrounded conductors for a 40A circuit from 8 AWG to 6 AWG, you would also need to increase the size of your EGC. If your EGC was 10 AWG, what size would it need to be now (Figure 250-178)?[/FONT]
[FONT=Arial, Helvetica, sans-serif](a) 12 AWG (b) 8 AWG (c) 6 AWG (d) 4 AWG[/FONT]
[FONT=Arial, Helvetica, sans-serif]Answer: (b) 8 AWG[/FONT]
​
[FONT=Arial, Helvetica, sans-serif]The circular mil area of 6 AWG is 59 percent greater than that of 8 AWG (26,240 cmil/16,510 cmil) [Chapter 9, Table 8].[/FONT]
[FONT=Arial, Helvetica, sans-serif]The EGC for a 40A protection device can be 10 AWG (10,380 cmil) [Table 250.122], but you must increase it in size by a multiplier of 1.59.[/FONT]
  • [FONT=Arial, Helvetica, sans-serif]EGC Size = 10,380 cmil x 1.59[/FONT]
  • [FONT=Arial, Helvetica, sans-serif]EGC Size = 16,504 cmil[/FONT]
  • [FONT=Arial, Helvetica, sans-serif]EGC Size = 8 AWG, Chapter 9, Table 8[/FONT]
Click to expand...
[/FONT]
 
george nicholson said:
?2) The "continuous" should be stated as this--- " the ground must be a conductor running from the panel ground buss to the disconnect NOT a ground conductor mechanically connecetd to the j-box at the start of the flex. It muts be connected to the ground buss in the panel or pipe solid with no flex to the disconnect which is not possible. I say he is incorrect about this...
Click to expand...

I agree with you his request is not NEC! Notice 250.118 for equipment grounding conductors, ?shall be one or more or a combination of the following?.

You have to install an effective ground fault path not continuous in the sense as grounding electrode conductor.

george nicholson said:
3) The voltage drop is not an issue we are only 90' to 150' from the panel and wire is actually 1 size larger than required but protected correctly?
Click to expand...

If you increased the phase conductors you must increase the EGC proportionally, voltage drop does have to be involved 250.122(B).

george nicholson said:
4) Again he wants a #10 green starting at ground bus in panel to disconnect on unit and tells me to find code that says I can not start the ground in the j-box. He will not show it to me...
Click to expand...

What he wants is not supported by the NEC, he has the burden of proof in that he needs to show you the specific violation (this is not an esthetical issue).

If you have used any item or combination of items listed in 250.118 and it is an effective ground fault path then you have installed an NEC acceptable equipment ground.
 
What if....
This circuit had been run using some flavor of AC cable..say a 6/3.
Would the cable now need to be removed and a similar flavor of MC installed?

The EI is out of touch here.
 
Originally Posted by Dennis Alwon
Let me put a wrench in the works--- did you read art. 250.122(B) and see if that affects you. I believe it will.
Click to expand...

OK, this is correct using 250.122 (B)

Originally Posted by george nicholson
4) Again he wants a #10 green starting at ground bus in panel to disconnect on unit and tells me to find code that says I can not start the ground in the j-box. He will not show it to me...
Click to expand...

With that said ask the inspector why he is requiring you to install a code violation?
 
ceb58 said:
OK, this is correct using 250.122 (B)
Click to expand...

Why do you say that? Did you read the example posted below mine-- almost the same scenario. If the wire size needed is a #8 and the op upsized the wire to #6 then the egc will have to be one size larger - a #8
 
Dennis Alwon said:
?read the example posted below mine-- almost the same scenario. If the wire size needed is a #8 and the op upsized the wire to #6 then the egc will have to be one size larger - a #8
Click to expand...

Dennis I agree :):

10,380 CM(#10) x 1.59%(#10/#8 CM's) multiplier = 16,504 CM?s meaning the EGC must be at least this size.

Chapter 9 & Table 8 show this result as #8 (16,510).

The EGC must increase in size proportionally according to the circular mil area of the [phase] conductors.
 
tryinghard said:
Is this in light of 250.119(B)? If so it?s compatible with NEC.
Click to expand...
Yeah I must be missing something here if you have a #8 from disco to panel and from disco to unit strip it where exposed and call for a re inspection
 
Dennis Alwon said:
Why do you say that? Did you read the example posted below mine-- almost the same scenario. If the wire size needed is a #8 and the op upsized the wire to #6 then the egc will have to be one size larger - a #8
Click to expand...

Yes, I did read it. In the original post he stated that the units requried #10.
Then the op changes to #8 and #6
My point was if the wire size changed and by code he needs #8 (as you pointed out) the op has stated the insp. wants a #10 pulled all the way back to the panel. Then would the inspector not be asking for him to install a violation?
 
ceb58 said:
Yes, I did read it. In the original post he stated that the units requried #10.
Then the op changes to #8 and #6
My point was if the wire size changed and by code he needs #8 (as you pointed out) the op has stated the insp. wants a #10 pulled all the way back to the panel. Then would the inspector not be asking for him to install a violation?
Click to expand...

Gotcha. I thought you were saying that the #10 was compliant with 250.122(B). Yeah, that was my point that the inspector missed the upsize. Instead of leaving the #8 with green tape--such a terrible thing :roll:-- he is calling for a #10 that is green-- a violation supposedly worse than what's there.
 
Status
Not open for further replies.
Top