Fused ground

Archive Public Archive
#1

Originally Posted By: pdacey
This post was automatically imported from our archived forum.


Opened one of three disconnects for the ac condensers and found this. The middle conductor is the ground and it has a barrel fuse in line. Is this really a problem? I know technically its not supposed to be there.


The other two disconnects had the middle fuse removed and the ground wires connected to the top terminals.
![](upload://lgCT5eXhvcrEE29Yw2sqpJeFB62.jpeg)

--
Slainte!

Patrick Dacey
swi@satx.rr.com
TREC # 6636
www.southwestinspections.com

#2

Originally Posted By: Greg Fretwell
This post was automatically imported from our archived forum.


Yup, that is wrong

#3

Originally Posted By: jpope
This post was automatically imported from our archived forum.


If one of the fuses at a hot leg (ungrounded conductor) blew, that “ground” would act as the neutral (grounded conductor) for the remaining hot conductors. You would then have a fused neutral (if you don’t already consider it as such).


If (somehow) the fuse at the "ground" blew, or became inoperable, you would no longer have an equipment grounding conductor for the appliance.

Based on what I can see, I would say that it warrants correction.

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

#4

Originally Posted By: pdacey
This post was automatically imported from our archived forum.


Thanks Jeff for a nice clear and quick explanation.

–
Slainte!


Patrick Dacey
swi@satx.rr.com
TREC # 6636
www.southwestinspections.com

#5

Originally Posted By: bbadger
This post was automatically imported from our archived forum.


I ‘know wrong’ when I see it but I am not finding a clear code section for this yet.


There is this generally applied to neutrals.

Quote:
240.22 Grounded Conductor.
No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met:

(1)The overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently.

(2)Where required by 430.36 or 430.37 for motor overload protection.


--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
#6

Originally Posted By: jpope
This post was automatically imported from our archived forum.


conductor Bob, or a grounding conductor?

–
Jeff Pope


JPI Home Inspection Service


“At JPI, we’ll help you look better”


(661) 212-0738

#7

Originally Posted By: bbadger
This post was automatically imported from our archived forum.


Jeff that is my problem here, so far I have not found a code section I think addresses this directly. icon_confused.gif


The title of 240.22 is indeed Grounded conductor, we are told that conductor in the picture is the EGC.

So it seems 240.22 can not be cited here, but then when we read 240.22 it says "any conductor that is intentionally grounded"

So a look at Article 100 is in order.

Quote:
Grounding Conductor, Equipment. The conductor used to connect the non?current-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately derived system.


That definition does not say that an EGC is intentionally grounded, it says it is connected to the grounded conductor.

However the definition of grounded conductor does use that term.

Quote:
Grounded Conductor. A system or circuit conductor that is intentionally grounded.


So no matter how hard I try I can not say that 240.22 applies here.

I can not find a section yet that does, I am looking and posted the question at Mike Holt's.


By the way I made no references to NACHI or HIs.

--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
#8

Originally Posted By: bbadger
This post was automatically imported from our archived forum.


Here is the thread I started at Holt’s.


http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=008365

No secrets. ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)

--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN

#9

Originally Posted By: Greg Fretwell
This post was automatically imported from our archived forum.


When in doubt you can always pull out 110.3(B). That is 3 phase equipment on single phase. icon_wink.gif


I had the 250.124(B) but I see that was covered. It isn't really a switch.

I like the 250(A)(5) answer
"(5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit..."
A fuse is anything but permanent.

#10

Originally Posted By: rmoore
This post was automatically imported from our archived forum.


Greg Fretwell wrote:

A fuse is anything but permanent.


Yup, and the scary thing, at least to me, is that there would be no indication for a homeowner that anything was amiss until something went terribly wrong.

Codes are great, but sometimes a simple "common sense" explanation about why it's a potential safety problem should suffice.

--
Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com
#11

Originally Posted By: bbadger
This post was automatically imported from our archived forum.


Greg Fretwell wrote:
When in doubt you can always pull out 110.3(B). That is 3 phase equipment on single phase. ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


I wanted anything but 110.3(B)

Most three phase disconnects are allowed on single phase, the label says to use the two outer poles as has been done here.

Greg Fretwell wrote:
I like the 250(A)(5) answer
"(5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit..."
A fuse is anything but permanent.


I agree this is the best section brought up yet.

I really thought there would have been something a little more directly related to this like.

"Overcurrent devices shall not be installed in EGCs"

I guess it comes down to common sense, no one has to be told not to stick a fork in their eye......but then again there it is in the picture, an EGC with a fuse.

--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
#12

Originally Posted By: pdacey
This post was automatically imported from our archived forum.


bbadger wrote:
.... no one has to be told not to stick a fork in their eye......


No one had to be told that coffee was hot either, until it spilled in that woman's lap. ![icon_rolleyes.gif](upload://iqxt7ABYC2TEBomNkCmZARIrQr6.gif)

--
Slainte!

Patrick Dacey
swi@satx.rr.com
TREC # 6636
www.southwestinspections.com
#13

Originally Posted By: pabernathy
This post was automatically imported from our archived forum.


lol…ok Bob…I read the information on Mike Holts site forum and here and just wanted to feed fuel to this…lol…


I would have to say 250-2(d) would be my best answer...

(d) Performance of Fault Current Path. The fault current path SHALL BE permanent and electrically continuous, shall be capable of safely carrying the maximum fault likely to be imposed on it, and shall have sufficiently low impedance to facilitate the operation of overcurrent devices under fault conditions....

My opinion is with a fuse it cant be permanent..and most certainly will not be continuous....if the fuse happen to blow or fail...

BTW...I only had my 1999 NEC with me today...lol....VA is still in the 1999 and I had a class to teach earlier to I had it with me at the office here.

But of all the ones I have seen...

I would have to agree the best I can see right now is

--
Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com

#14

Originally Posted By: rmoore
This post was automatically imported from our archived forum.


In Patrick’s photo it looks like all the fuses are the same size (?). In the case of a direct short of one hot leg to the chassis of the condensor wouldn’t it be possible (or at least a toss-up) for only the EGC fuse to blow? That would leave the metal casing of the condensor unit energized waiting for some unsuspecting soul to zap themselves. Maybe I’m missing something but that scenario alone makes the set-up so obviously wrong.


I too am surprised that "Overcurrent devices shall not be installed in EGCs" isn't actually in the NEC, but then I also can't find the section on "Don't stick a wet finger in a hot light socket".

--
Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com

#15

Originally Posted By: pabernathy
This post was automatically imported from our archived forum.


The point is with it comes to the ECG being fuses…it could be removed…blow and so on but in any case the fact it is not permanent is a problem nor continuous upon being removed or blown…as it could distrube the path for the fault and you NEVER can assume what a home owner will do when one of the outside fuses blow and they see the middle one and say…hmmm…I will just use it until I get a new fuse…it is HOT outside today…I dont need that ground right now…


The NEC kinda has a round about way of saying this...could it be more clear..sure....but then my job would be TOO easy...lol

--
Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com