Electric Code circa 1980 (grounding)

[Homeownerinburb]

Hey,

I don't have any idea how the code read in 1980.

Specifically, I am looking for how the rules regarding the grounding of a residential service panel (100) amp were different then as compared to now.

I expect that the matter of bonding to the water system was the friendly shortest route to the copper rule, as compared to today's "withing five feet of entering the building" rule.

Thanks.

[jwelectric]

I am very busy for the next few days and don’t have the time to look it up but somewhere around that time era it was required to make and keep all metal piping system electrically continuous from end to end.

Just as today the electrode is only the part of the pipe that is in direct contact with earth. Today’s verbiage states that we are allowed to use only the first five feet of metal water pipe for the grounding path to the electrode. This first five feet is not electrode.

250.53(D) (1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment..

Note the use of “grounding path”

250.68(C) (1) Interior metal water piping located not more than 1.52 m (5 ft) from the point of entrance to the building shall be permitted to be used as a conductor to interconnect electrodes that are part of the grounding electrode system.

The Exception to this allows the metal water pipe in industrial buildings to land anywhere as long as certain rules are followed.

[Homeownerinburb]

I am very busy for the next few days and don’t have the time to look it up ......

Appreciate it. A realtor that hires me asked me to look at a house he is representing. It has a 100 amp panel installed approx 1980.

The buyer has called out the quality of the grounding on the panel, and my guy asked me to assess what is there.

There is a solid #6 in a shield running under the house to where the water comes up out of the ground. It WAS clamped to the plumbing before a plumber found it an impediment and disconnected it. It is just flapping around.

So, I am looking to know what was the standard of the time, so that I can write up a report referencing that.

I intend to drive a ground rod at that point and bond the water to that rod with the existing #6. Which reflects current standards as I understand them.

[jwelectric]

Drive two rods and do what you say and we know that it will fly then

[hj]

as long as it is a metallic water pipe, it serves the same function as a driven ground rod. But, having the ground clamp removed from the water pipe COULD cause serious problems it there were a problem in the utilitie's supply wiring, although , conversely, it could "mask" those problems if it were connected.

[Homeownerinburb]

Drive two rods and do what you say and we know that it will fly then

Yeah. And this is a riverbed, the rods just slide into position under the force of gravity, so I can't complain.

[DonL]

Appreciate it. A realtor that hires me asked me to look at a house he is representing. It has a 100 amp panel installed approx 1980.

The buyer has called out the quality of the grounding on the panel, and my guy asked me to assess what is there.

There is a solid #6 in a shield running under the house to where the water comes up out of the ground. It WAS clamped to the plumbing before a plumber found it an impediment and disconnected it. It is just flapping around.

So, I am looking to know what was the standard of the time, so that I can write up a report referencing that.

I intend to drive a ground rod at that point and bond the water to that rod with the existing #6. Which reflects current standards as I understand them.

I agree with JW if you are not sure what you have, make it right.

I think you may find a 8 Foot Ground rod, Before the #6 goes under the house. It may be under the dirt some.

1 8 foot Rod was the norm in the day, but if you make a mod then you should meet today's codes.