Why no splicing of ground rod conductors ?

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I think it has more to do with how much they used to rely on water piping for neutral continuity.
 
Lightning currents in 10's or even 100's of kA.
Magnetic forces due to current will BREAK cable connections long before any high resistance connection fails due to arcing, etc.
Have BROKEN 250 MCM copper that had a right angle connection (2 ea 1/2" bolts on crimped lugs) with a 4E6 amp, 100 us lightning pulse simulator. the 4E6 current was high enough that the connection broke AND the 250 MCM broke where the other end was constrained at the top of a big ignitron used for pulse generation.
At rod or pipe, besides the rationale already mentioned that there are no good alternatives, at least one end is held relatively rigid - even though the 250 MCM that BROKE the cable was bolted to a 1/2" thick plate welded to 6 inch channels.
 
electrofelon said:
Do you have any evidence that mechanical splices would be less reliable in those situations? How does the splice resistance even really matter when your ground rods have easily 25 ohms or more resistance?
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The thing is, it applies to all GEC’s, not just ground rods. The CMP probably just made a rule to cover all GEC’s using the KISS philosophy.
 
Greg1707 said:
I am restating the question. Electrical systems allow lots and lots of splices. It seems that only the GEC is not allowed to be spliced. Why?
What is the worst thing that can happen if a GEC fails? What is the worst thing that can happen if the conductor to a hospital operating room fails?
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The GEC IS allowed to be spliced.
The saying it’s not allowed to be spliced is an old wives tale.

All wires can be spliced. There are certain rules on how it’s done.
 
hillbilly1 said:
The thing is, it applies to all GEC’s, not just ground rods. The CMP probably just made a rule to cover all GEC’s using the KISS philosophy.
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I'm still not buying it. I doubt splice strength during a lightning event is/was a reason, and even if it was, I'll bet you a Reuben sandwich there was never any scientific analysis, just some idiot (s) thinking it is a good code requirement.
 
electrofelon said:
I'm still not buying it. I doubt splice strength during a lightning event is/was a reason, and even if it was, I'll bet you a Reuben sandwich there was never any scientific analysis, just some idiot (s) thinking it is a good code requirement.
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I've always felt that way too because of lack of evidence to the contrary.
 
junkhound said:
Lightning currents in 10's or even 100's of kA.
Magnetic forces due to current will BREAK cable connections long before any high resistance connection fails due to arcing, etc.
Click to expand...

Reminds me of the time I saw a GEC in full bolted fault action
Many years ago...
I got called out to a house after a rare snow/ice storm, Homeowner had downed line and there house was vibrating.
They called 911 and POCO but they could not get thru.
So they called my cell.
When I got there
Steam was coming out of all the water taps, and the water pipes were violently shaking in the walls, and the power was going crazy.
It is an old house so all metal piping, galvanized steel.
I had the family get out of the house.
Out back I saw a tree had taken down a overhead service drop, bent the mast 90 degrees at the hub on top the meter.
The neutral guy wire was snapped but the 2 hots were still connected.
One of the hots had apparently welded itself to the meter can or the hub.
I could see and here the ground wires vibrating and had melted a hole in the snow and ice around what was probably a groundrod.
I did not want to cut the line with my klines and called a coworker for backup.
I took the the opportunity to ammeter the #4 to the water pipe and the #6 to the rods while I waited for my co worker to get there.
I dont remember the exact numbers but the water pipe was just over 100 Amps, ground rods were less.
Unforgettable experience.
Probably more stuff like that in the old days, when emergency response times were longer.
 
Just a stupid question, did you think to throw the main breaker open? It’s great that you measured the amp draw on the grounds but just asking?


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Exactly, there was an outside panel and a inside panel, I was able to shutoff everything in the inside panel.
The mast, downed lines, broken tree branches and snow were blocking the outside panel.
Really the sounds that house was making are what sticks with me.
 
tortuga said:
Reminds me of the time I saw a GEC in full bolted fault action
Many years ago...
I got called out to a house after a rare snow/ice storm, Homeowner had downed line and there house was vibrating.
They called 911 and POCO but they could not get thru.
So they called my cell.
When I got there
Steam was coming out of all the water taps, and the water pipes were violently shaking in the walls, and the power was going crazy.
It is an old house so all metal piping, galvanized steel.
I had the family get out of the house.
Out back I saw a tree had taken down a overhead service drop, bent the mast 90 degrees at the hub on top the meter.
The neutral guy wire was snapped but the 2 hots were still connected.
One of the hots had apparently welded itself to the meter can or the hub.
I could see and here the ground wires vibrating and had melted a hole in the snow and ice around what was probably a groundrod.
I did not want to cut the line with my klines and called a coworker for backup.
I took the the opportunity to ammeter the #4 to the water pipe and the #6 to the rods while I waited for my co worker to get there.
I dont remember the exact numbers but the water pipe was just over 100 Amps, ground rods were less.
Unforgettable experience.
Probably more stuff like that in the old days, when emergency response times were longer.
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Guessing maybe the supply side neutral was broken, pulled out, burned off, etc. in that event or else maybe fault current would have been high enough to eventually trip the transformer protective device?
 
kwired said:
Guessing maybe the supply side neutral was broken, pulled out, burned off, etc. in that event or else maybe fault current would have been high enough to eventually trip the transformer protective device?
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Yeah, you would hope…
Some guys don’t understand XF fusing and will fuse a 15kVA on the high side with a 5 or 6 amp fuse @13,200V.
That’s a lot of amps if one leg is welded to the meter can. With N and G burnt out, not enough fault current to blow the fuse..
 
Hv&Lv said:
Yeah, you would hope…
Some guys don’t understand XF fusing and will fuse a 15kVA on the high side with a 5 or 6 amp fuse @13,200V.
That’s a lot of amps if one leg is welded to the meter can. With N and G burnt out, not enough fault current to blow the fuse..
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Interesting, yeah old part of town with lots of overhead, they use 50kva's and feed 3-5 houses down the alley.
It was probably pulling ~180 Amps tops

I notice those 50's in the old area's because they have two primary bushings and kinda a oval shape.
Newer areas just have one 'elbow' and are underground feed.

kwired said:
Guessing maybe the supply side neutral was broken, pulled out, burned off, etc. in that event or else maybe fault current would have been high enough to eventually trip the transformer protective device?
Click to expand...
Yeah the neutral / guy wire was snapped.
The only thing that really melted was the CATV service.
The rest of the house was fine after I replaced the meter and the mast.
 
tortuga said:
Yeah the neutral / guy wire was snapped.
The only thing that really melted was the CATV service.
The rest of the house was fine after I replaced the meter and the mast.
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we see that occasionally after a storm when a N is broke and the HO doesn’t shut down power in the house.
The CATV is bonded at the house and the pole or padmount and is the return path.
With a heavy load that outer wire mesh can’t handle the current and can get very hot
 
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