Thread: Electrical grounding on 40 year old house

Two questions
1) If only electrical panel ground is to copper water pipe (all I can find) and dielectric union is installed between incoming underground galvanized water pipe and interior copper pipe, do I have a problem with short circuit protection?

2) I now have some woodworking equipment in my basement where there is only one receptacle which does not have a ground wire from panel. I want to run a 12 ga. ground wire from this receptacle to a ground lug on galvanized water pipe side for short circuit protection. is this safe?

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Originally Posted by Ron Davis

Two questions
1) If only electrical panel ground is to copper water pipe (all I can find) and dielectric union is installed between incoming underground galvanized water pipe and interior copper pipe, do I have a problem with short circuit protection?

2) I now have some woodworking equipment in my basement where there is only one receptacle which does not have a ground wire from panel. I want to run a 12 ga. ground wire from this receptacle to a ground lug on galvanized water pipe side for short circuit protection. is this safe?

#1 - Maybe.... best solution is to ensure good grounding via rods buried in the earth. You could/should also bond any metal pipes or other materials (gas piping, coax cable, etc.) via the same panel/system. You can also install a jumper across the dielectric connection but the rods in the earth are still a good idea.

#2 - No.. not correct - you should bond this through the service equipment panel which is grounded via the method mentioned in #1. Clamping on to water pipes is outdated and not a good practice... go through the panel.

Originally Posted by Ron Davis

Two questions
1) If only electrical panel ground is to copper water pipe (all I can find) and dielectric union is installed between incoming underground galvanized water pipe and interior copper pipe, do I have a problem with short circuit protection?

2) I now have some woodworking equipment in my basement where there is only one receptacle which does not have a ground wire from panel. I want to run a 12 ga. ground wire from this receptacle to a ground lug on galvanized water pipe side for short circuit protection. is this safe?

1) The grounding electrode system doesn't have much to do with "short circuit" protection.

2) Very dangerous idea. The grounding electrode system does not provide a low resistance path back to the source (transformer, usually), which is needed for "short circuit" protection.

Just asking, but during my research, I thought I read that gas pipe was not suppose to be grounded-comment?

I know it is outdated code, but I do have 1-1/4" galvanized water pipe 3 ft. (at foundation anyway) underground with at least a 40 foot run to water meter (which does not appear to have been retrofitted with dielectric couplings since construction 40 years ago). I would think that this would make a proper ground return to utility transformer-comment?

Originally Posted by Ron Davis

Just asking, but during my research, I thought I read that gas pipe was not suppose to be grounded-comment?

Used as THE ground bad idea.... bonded to prevent if from carrying a charge.... good idea and has been the way it's done for the last 10 years or so (at least in my area).

A 1971/2-built home (40 years old) should have grounding type receptacles in its basement, finished or unfinished, and elsewhere throughout the residence. Grounding type receptacles have been required throughout since the early/mid 60s editions of the NEC (and since the mid 40s in laundry areas).

There are other methods of employing an equipment grounding conductor. You did not mention the wiring method utilized for the basement.

For example conductors pulled through bonded EMT and bonded metalic boxes (common for unfinished basement areas) the bonded metallic tubing and boxes providing equipment grounding with insulated ungrounded ('hot's) and grounded conductors ('neutral's) within, have been and are a legitimate equipment grounding conductor and wiring method. You also did not indicate if you have existing grounding type receptacle(s) in the basement.

You also seem to be very confused about bonding and grounding.

I suggest you employ the services of a licensed electrical contractor, you obviously are not qualifed to be modifying your electrical system.