What year did bonding requirements change also when ground rod requirements change?

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DaveTap

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For all you history buffs out there I'm trying to determine what year the code changed to require not bonding at both panel and meter socket. Also what year did code change from using one ground rod to two with the exception?
 
DaveTap said:
Also what year did code change from using one ground rod to two with the exception?
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If you're thinking of the 25 ohm exception- 250.53 (A)(2)-, iirc that came along in 2008?- hopefully someone else can confirm.

I bet virtually nobody does that test vs. driving a 2nd rod, but you never know-getting that 25 ohms is just so important.:roll:
 
DaveTap said:
For all you history buffs out there I'm trying to determine what year the code changed to require not bonding at both panel and meter socket.
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I'm confused by the question. Are you asking about bonding at a service disconnect or a sub-panel?

I have worked on a fair number of old round meter sockets on the outside of the house going straight into the breaker panel or fuse box inside the house and all of them are bonded in both places, so I would say never.

Also what year did code change from using one ground rod to two with the exception?
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Two ground rods have been required for a long time.
 
DaveTap said:
For all you history buffs out there I'm trying to determine what year the code changed to require not bonding at both panel and meter socket. Also what year did code change from using one ground rod to two with the exception?
Click to expand...
Please clarify the question, improper use of terminology is likely making this confusing to know how to answer.

Meter sockets and panelboards have for very long time both required to be "bonded". To which conductor you bond them to can be different in different situations.

Grounding electrode conductor has also been able to land at either location for a very long time - per NEC. There are local rules in places or even POCO rules that do come into play in this sort of discussion sometimes though.
 
user 100 said:
If you're thinking of the 25 ohm exception- 250.53 (A)(2)-, iirc that came along in 2008?- hopefully someone else can confirm.

I bet virtually nobody does that test vs. driving a 2nd rod, but you never know-getting that 25 ohms is just so important.:roll:
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I think rule was already in place and only the wording changed in '08?
 
readydave8 said:
I think rule was already in place and only the wording changed in '08?
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Correct. The way it was worded prior was that you as the installer could ask the AHJ to prove the resistance was over 25 ohms before he could make you add a second electrode. They way it is worded now you have to prove to the AHJ that the resistance is 25 or less or you will have a second electrode. The logic of what/how it should be installed has remained the same all along
 
Back in the 80's when I first started we bonded neutral (grounded conductor) to ground (equipment grounding conductor) at both the meter socket and the panel (usually the green screw came already installed) ... now to prevent parallel paths we only bond at one... usually the meter socket and we keep neutrals and grounds isolated from each other... even installing a separate grounding bus to terminate grounds of BX, UF, Romex, etc. I should clarify that near Chicago all services are required to be in Rigid or IMC Conduit. If I remember about the same time we also had to change to using grounding bushings for concentric knockouts, but that may have come later.
Does anyone remember what year that changed? I'm thinking around 1999?
 
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DaveTap said:
Back in the 80's when I first started we bonded neutral (grounded conductor) to ground (equipment grounding conductor) at both the meter socket and the panel (usually the green screw came already installed) ... now to prevent parallel paths we only bond at one... usually the meter socket and we keep neutrals and grounds isolated from each other... even installing a separate grounding bus to terminate grounds of BX, UF, Romex, etc. I should clarify that near Chicago all services are required to be in Rigid or IMC Conduit. If I remember about the same time we also had to change to using grounding bushings for concentric knockouts, but that may have come later.
Does anyone remember what year that changed? I'm thinking around 1999?
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Your question makes a little more sense now that I see what you do in Chicago does not match the NEC when it comes to services. I thought the only, or at least the major, difference was you guys had to use conduit for everything.
 
DaveTap said:
Back in the 80's when I first started we bonded neutral (grounded conductor) to ground (equipment grounding conductor) at both the meter socket and the panel (usually the green screw came already installed) ... now to prevent parallel paths we only bond at one... usually the meter socket and we keep neutrals and grounds isolated from each other... even installing a separate grounding bus to terminate grounds of BX, UF, Romex, etc. I should clarify that near Chicago all services are required to be in Rigid or IMC Conduit. If I remember about the same time we also had to change to using grounding bushings for concentric knockouts, but that may have come later.
Does anyone remember what year that changed? I'm thinking around 1999?
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Unless you are doing something different in Chicago area, there is no EGC at the (service supplied) meter and hasn't been one there well before 1980's. Everything on the supply side and including the service disconnecting means is bonded to the grounded service conductor. This can put metal raceways, like between a meter socket and the service disconnect enclosure, in parallel with the grounded conductor, but NEC doesn't deem this as objectionable current.
 
kwired said:
Correct. The way it was worded prior was that you as the installer could ask the AHJ to prove the resistance was over 25 ohms before he could make you add a second electrode. They way it is worded now you have to prove to the AHJ that the resistance is 25 or less or you will have a second electrode. The logic of what/how it should be installed has remained the same all along
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That's what I was thinking of.:thumbsup:

As ActionDave said above 2 rods has been the rule for a long time (in lieu of <25 ohms for a single rod)- probably many decades- that 25 ohm requirement was around in the 1930's I think.
 
I once heard the supposed explanation behind origin of the 25Ω rule. I think it came from some really obscure telephone/telegraph design requirement. Anyone know that story?
 
ActionDave said:
Your question makes a little more sense now that I see what you do in Chicago does not match the NEC when it comes to services. I thought the only, or at least the major, difference was you guys had to use conduit for everything.
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Yep... metal conduit for almost everything... especially service entrances and It's supposed to match NEC but of course Chicago has its own code loosely based on the NEC...
 
kwired said:
Unless you are doing something different in Chicago area, there is no EGC at the (service supplied) meter and hasn't been one there well before 1980's. Everything on the supply side and including the service disconnecting means is bonded to the grounded service conductor. This can put metal raceways, like between a meter socket and the service disconnect enclosure, in parallel with the grounded conductor, but NEC doesn't deem this as objectionable current.
Click to expand...

kwired said:
Unless you are doing something different in Chicago area, there is no EGC at the (service supplied) meter and hasn't been one there well before 1980's. Everything on the supply side and including the service disconnecting means is bonded to the grounded service conductor. This can put metal raceways, like between a meter socket and the service disconnect enclosure, in parallel with the grounded conductor, but NEC doesn't deem this as objectionable current.
Click to expand...

Metal conduit is usually the EGC here... (now supplemented by wires from metal boxes to yokes of outlets and in some jurisdictions switches.)
In an effort to improve connection quality of the service entrance conduit we have to install grounding bushings on both ends and connect to the GEC in meter socket and a wire to a ground bus (or lug) in the service panel. To prevent neutral current in the service entrance conduit the bonding screws in service panels are removed. Some inspectors want the GEC run all the way through the entrance conduit to the service panel ground bus and connected at every ground lug on the way.
 
The NEC permits the grounded conductor to be both the grounded and grounding conductor for the service disconnect enclosure and everything on the line side of the service disconnect. This applies both for metallic and non-metallic service wiring methods.
 
DaveTap said:
Metal conduit is usually the EGC here... (now supplemented by wires from metal boxes to yokes of outlets and in some jurisdictions switches.)
In an effort to improve connection quality of the service entrance conduit we have to install grounding bushings on both ends and connect to the GEC in meter socket and a wire to a ground bus (or lug) in the service panel. To prevent neutral current in the service entrance conduit the bonding screws in service panels are removed. Some inspectors want the GEC run all the way through the entrance conduit to the service panel ground bus and connected at every ground lug on the way.
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What you described is not an NEC requirement. If you are ahead of the service disconnecting means there is no EGC in the NEC you bond everything requiring bonding to the grounded conductor, this can and does allow for parallel paths for grounded conductor current. You apparently have local rules that want to prevent those parallel paths.
 
The only thing I can say is that when I tested for my Master's way back when, the NEC was about 1/4 the thickness it is today..
 
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