Troubleshoot

Status
Not open for further replies.
B

blueheels2

Senior Member
Location
Raleigh, NC
Occupation
Electrical contractor
Just want to run this past those smarter than myself. Concrete floor, masonry wall cabin with 100 amp service. FPE main panel, No ground rods. Initially I looked and thought the can was bonded but after a shock last night I quit working and came back and did a thorough service investigation this morning. Surprise neutral was floating. One branch ckt neutral was landed on a ground bar. I added a 4 wire sub panel neutral ground separation. It looked initially like there was a bonding screw on the neutral bar so I went about my business as if things were okay. EMT between panels. Last night I was running EMT and was kneeling on the concrete (wet) when I got shocked. Today I am adding ground rods new feeder and new main panel. I believe this will clear up the problem. Am I missing anything. I assume I got shocked because my body was a better return path than my subpanel pipe and ground which was tied to the neutral. I know my pipe and ground gave me a false reading to the can from the floating neutral bar this morning. Hope this makes sense.
 
You have a short to ground somewhere, the lack of bonding is failing to trip the overcurrent protection. You can narrow it down by going from a known good connection to the neutral to the concrete, turn off the breakers one by one until the voltage disappears, then you will know what circuit and it's loads to check. Likely a bad water heater element, but could be anything from miswiring, to a hot against an ungrounded box. (boxes mounted in the concrete does not mean there grounded, this can make the concrete "Live" to something bonded.)
 
Does it look like this ?

http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/IMG_0180.jpg

208 wild leg with floating neutral. I noted it buy the orange leg (locally correct)

X -Pizza hut on the other side of Cary Town Center.

Not many people have ever seen this setup. and it's very, very dangerous!

This is only the second time I've ever seen it in 15 years.
 

Attachments

  • IMG_0180.jpg
    IMG_0180.jpg
    147.1 KB · Views: 0
blueheels2 said:
Just want to run this past those smarter than myself. Concrete floor, masonry wall cabin with 100 amp service. FPE main panel, No ground rods. Initially I looked and thought the can was bonded but after a shock last night I quit working and came back and did a thorough service investigation this morning. Surprise neutral was floating. One branch ckt neutral was landed on a ground bar. I added a 4 wire sub panel neutral ground separation. It looked initially like there was a bonding screw on the neutral bar so I went about my business as if things were okay. EMT between panels. Last night I was running EMT and was kneeling on the concrete (wet) when I got shocked. Today I am adding ground rods new feeder and new main panel. I believe this will clear up the problem. Am I missing anything. I assume I got shocked because my body was a better return path than my subpanel pipe and ground which was tied to the neutral. I know my pipe and ground gave me a false reading to the can from the floating neutral bar this morning. Hope this makes sense.
Click to expand...

I'll keep this to the point. If your bonding is correct, that is all metal, electrodes, etc. are electrically connected with a low impedance connection and you are still getting shocks from the earth, you likely have a POCO problem.

So, start with a good bonding inspection. Oh, and you can add all the ground rods you want, but they won't keep you from getting zapped. That's not why we use them.
 
cadpoint said:
Does it look like this ?

http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/IMG_0180.jpg

208 wild leg with floating neutral. I noted it buy the orange leg (locally correct)

X -Pizza hut on the other side of Cary Town Center.

Not many people have ever seen this setup. and it's very, very dangerous!

This is only the second time I've ever seen it in 15 years.
Click to expand...

I don't see any problem in the photos, and that set up is very common, what are you seeing (or not seeing)? Assuming we are looking at service equipment.
 
blueheels2 said:
...Last night I was running EMT and was kneeling on the concrete (wet) when I got shocked. Today I am adding ground rods new feeder and new main panel. I believe this will clear up the problem.
Click to expand...
The additon of ground rods will have nothing to do with solving the problem.
... I assume I got shocked because my body was a better return path than my subpanel pipe and ground which was tied to the neutral.
Click to expand...
You got shocked because there was a voltage potential between the two points that you were touching. I has nothing to do with how good one current path is as comprared to another current path. The current flows on all available paths. The current is divided in inverse proportion to the impedance of the paths. The voltage is the same across all of the parallel paths.
I know my pipe and ground gave me a false reading to the can from the floating neutral bar this morning. Hope this makes sense.
Click to expand...
I have no idea what this "false" reading you are talking about means.
 
cadpoint said:
Does it look like this ?

http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/IMG_0180.jpg

208 wild leg with floating neutral. I noted it buy the orange leg (locally correct)

X -Pizza hut on the other side of Cary Town Center.

Not many people have ever seen this setup. and it's very, very dangerous!

This is only the second time I've ever seen it in 15 years.
Click to expand...

Maybe I am just old and dumb but i don't see an issue here. How can the neutral be floating when it is grounded?
 
petersonra said:
Maybe I am just old and dumb but i don't see an issue here. How can the neutral be floating when it is grounded?
Click to expand...
You are not old and dumb, you are experienced. Looks to me like the bonding screws are installed in both disconnects in the photo. I don't know what problem cadpoint has with that install based only on what we can see in the photos. I get the feeling he is uncomfortable with a system with a "wild leg", if he is not very accustomed to that system that is fine, does not mean it is dangerous, those systems are all over the place around here.
 
I apoligize to Blueheels for the thread highjack!

Voltages
A to B 249
A to C 248
B to C 245

A to G 124
B to G 213
C to G 124

This is from the disconnect on the left.

Now if in your neigborhood this is what you deal with daily I can't touch that.

I'm frankly saying that it is uncommon around here. This is in an area that is highly developed and the poco's aren't installing this type of installation and redo the service lateral all the time.
Maybe I'm a horse's rear end for impling I know what I'm talking about, but the engineer was as surprised as I when we ID'd this. But you are correct I don't know how to electrically describe it other than to say 120/240 with a 240 stinger...

This is the Service disconnects above the poco gutter.

Heres the inside panels to http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/insidefloat.jpg

Heres the panel from the left disconnect
http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/inside2.jpg

here's the panel from the right disconnect
http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/inside1.jpg

Should we go into things that are truely wrong or missing in all these pictures?

FYI one of the green wire in the mini disconnect panel goes off to bond the H2O.

First link
second link http://
Third link http://

I added these 3 again for those that use photobucket to help magnify things!
 
Last edited:
cadpoint said:
I apoligize to Blueheels for the thread highjack!

Voltages
A to B 249
A to C 248
B to C 245

A to G 124
B to G 213
C to G 124

This is from the disconnect on the left.

Now if in your neigborhood this is what you deal with daily I can't touch that.

I'm frankly saying that it is uncommon around here. This is in an area that is highly developed and the poco's aren't installing this type of installation and redo the service lateral all the time.
Maybe I'm a horse's rear end for impling I know what I'm talking about, but the engineer was as surprised as I when we ID'd this. But you are correct I don't know how to electrically describe it other than to say 120/240 with a 240 stinger...

This is the Service disconnects above the poco gutter.

Heres the inside panels to http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/insidefloat.jpg

Heres the panel from the left disconnect
http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/inside2.jpg

here's the panel from the right disconnect
http://i249.photobucket.com/albums/gg229/CADPoint/208 jigh leg/inside1.jpg

Should we go into things that are truely wrong or missing in all these pictures?

FYI one of the green wire in the mini disconnect panel goes off to bond the H2O.

First link
second link http://
Third link http://

I added these 3 again for those that use photobucket to help magnify things!
Click to expand...
Copy and paste the "IMG code" in your post and the picture will be visible in the post.

The Delta system with midpoint of one phase grounded is what results in having a "high leg". There are parts of the country where it is not common. But they are all over the place, and are an economical way for POCO to provide three phase for a service that is limited in load. They can be easily derived from only two phase conductors and a neutral in the case of "open delta" configured systems, and is also economical and easy to simply add a "stinger" transformer to an existing single phase system to make it three phase if limited three phase load is all that is needed.

In cases where there is a lot of power load and limited neutral loads it may be preferred to use this system over a wye system especially in the 240 volt class. Wye systems seem to be more universally preferred when talking 480 volt class, but there are 480 volt delta systems with a wild leg also it measures about 415 to ground with 240 to ground on the other two phases.
 
I'm confused by what you guys are suggesting is a "floating neutral". A floating neutral is a neutral bus with no connection back to the service source (open circuit on supply neutral). Absence of a ground-to-neutral bond is a "floating system". Is this latter what you are referring to?

When the OP states that there are no ground rods, that is a floating system, and it will bite you in the manner described by the OP. This is the exact topic I am referring to in the recent thread on grounding, and here is my posting. When you do not have a grounding electrode (ground rod), your entire system will float to an indeterminate voltage somewhere between the bounds of the primary-side phase voltages. That means that if the POCO primary was 2400 volts, for example, your secondary neutral is capable of floating as high as 2400-120=2280 volts.

All of your voltages from phase-neutral-phase will remain where you expect them (120/240 volts), but the entire system as a whole will float to a higher voltage relative to Earthen-ground.

This situation can go unnoticed for a long time, because if the secondary load is balanced, then the float (offset) voltage will remain near center (near zero). It rears its ugly head when you have an unbalanced load.

So for all of the members here that keep thinking that ground rods are only for lightning protection, this is (potentially) the exact reason and situation why this assertion is untrue. Of course I may be misunderstanding the OP's description and this is not a floating system after all, but the principle still stands. His notation that there are no grounding electrodes leads me to believe this is a floating system, and it tends to fit his symptoms (at least as I understand them).
 
Here is what you get if you just copy and paste the IMG tags from photobucket
inside1.jpg

inside2.jpg

insidefloat.jpg
 
As far as picking apart violations - not much there that is directly related to the fact it is a delta with high leg.

I do see a single pole breaker connected to what should be the high leg - what does that feed? Bet that breaker is not rated for anything but 120 volts.

There is also a 2 pole breaker connected to high leg. This is acceptable but can not be 120/240 rated breaker - it must be 240 only rated breaker.
 
cadpoint said:
But you are correct I don't know how to electrically describe it other than to say 120/240 with a 240 stinger...
Click to expand...
This configuration goes by a lot of different names, but it is very common in many parts of the country. In my experience, it is most often found in light-industrial areas where it can be common to have 240-volt single-phase loads and a few 3-phase loads. I prefer to call it a "Center-tapped delta" because the name is not dependent on transformer configuration, but Open-Delta and a few others are also commonly used.

SystemTypes-lo.jpg
 
cadpoint said:
But you are correct I don't know how to electrically describe it other than to say 120/240 with a 240 stinger...
Click to expand...

This system is much more common than you think.

It is properly describer, BY IEEE?ANSI as a 240/120V [3-phase 4-wire], center-tapped delta. The nominal high leg voltage is 208V based (it will actually be .867 x LL voltage)
For our industry it is most often called a 'wild-leg' or 'high-leg' system. Other terms are stinger, and bastard. when I learned the trade, in the mid-west this was called a christmas tree.
 
Status
Not open for further replies.
Top