Hi, I'm sorry for re-asking something that looks like it's asked several times a week, but I can't find specifics to my case, and trying to read through the NEC and it's making my head spin.

I have some ungrounded outlets in an old section of my house, the ungrounded wire (2 wire, 600 V) is not easy to trace, but obviously comes from some junction box, because every pair (triplet?) leaving the main breaker box is grounded to the grounding bar. I'd like to ground these outlets so I can use a computer/surge protector (sorry, can't use an ungrounded GFI). My thought is to run 12 gauge solid ground wire to one of the listed options in NEC 250.52 (A)(1)-(A)(7) or NEC 250.130 (C) are these the right places to be looking?

Option 1 is grounding to 250.130 (C) (3), however I believe this doesn't meet code because the junction box doesn't have a ground bar (?), but probably a wire-nut? But I don't remember for sure. It also is for a different circuit, or a parallel branch of the same circuit, but not a parent branch, is this a viable option? I can also ground to the conduit/junction box of a 220 line in the same location, but same problems as listed before.

Option 2 is grounding to 250.52 (A) (2), an I-beam that runs the length of the house and I can easily ground to, but I'm not sure the I-beam is connected to "earth" by one of those options, can I check the resistance between the house ground and the I-Beam and if it's less than 25 ohms (250.56) just ground to that? How else can I check if the I-beam is grounded in accordance with 250.56? Also if I do this, should I also ground the I-beam to the junction box listed above? I seem to remember reading that having two unconnected grounds can cause a "floating"(?) ground?

Option 3, this is the most work, and therefore the last option mentioned. I can ground to the first 5 feet of copper water pipe coming into the house from the earth, (need to verify it's copper, I'll have to use some paint solvent because the pipe's been painted at the only place where I can access it within 5 feet of the earth right after it comes into the house).

Do I have more options? What are or where can I find "Other Listed Electrodes" mentioned in 250.52(A)(6)?

These are the options I see for grounding the first outlet, the second outlet is wired to the first in a daisy chain with 3 wire romex, if I ground the first outlet does the second outlet meet code for ground?

As a partially unrelated question... I have one outlet that when tested, says grounded correctly, however when the power's off and I have the outlet pulled out, there doesn't appear to be a ground wire, could the outlet be grounded to the box which is grounded by the 2 wire+metal sheath (can't remember what it's called, sorry... ). When looking I don't see any conduit or ground wire attached to the box...

Thanks!
-David

Your not allowed to run a single wire.

Grounding at random locations rather than one point (neutral/ground bond at panel) changes ground potentials everywhere. Not good.

You have to run a new cable. Sorry.

You can put a GFCI on 2 wire circuit as long as it's labeled.

Consider a whole house surge protector. It will help.

The 2-wire metal sheath is sometimes allowed for grounding depending on the construction of the cable.

Your not allowed to run a single wire.
Darn, I thought I had read that you could, can you point me to specifics in the NEC? Also how would you ground to the first 5 feet of water pipe if you can't run a single wire?


Grounding at random locations rather than one point (neutral/ground bond at panel) changes ground potentials everywhere. Not good.

Does grounding to a ground that is connected to the ground bar in the main breaker box change the ground potential?



You have to run a new cable. Sorry.

Can't for various reasons including can't remove large sections of drywall, if this is the only option then I'll be running an extension cord from a grounded outlet so I can run the computer


You can put a GFCI on 2 wire circuit as long as it's labeled.
If I wasn't using a computer on this circuit, but as I mentioned above, this doesn't actually solve my problem.


Consider a whole house surge protector. It will help.
Thanks for the recommendation but above my budget.


The 2-wire metal sheath is sometimes allowed for grounding depending on the construction of the cable.
Thanks, but wasn't asking if it was allowed. I was asking if it could be causing the ungrounded-by-wire outlet to test as grounded, sorry for the confusion.

I feel that because I am asking a question that's been asked before, you didn't really read my questions as most of them were summed up in
Your not allowed to run a single wire. Can I get some more specific answers to my questions? Even if they're only good for furthering my knowledge because I can't use them "in this case", I'd at least like to know why not.

Thanks
-David

1: You can/should ground to the water pipe for the main ground within 5' of it entering the building. If it's 30' away, so be it. It acts as your grounding electrode and you don't need a ground rod.

What you cannot do is ground an outlet to an Ibeam and another to another section of copper pipe.

2) No. All pieces of equipment share the same reference. It's not current carrying except in fault conditions.

3) New cable. There are flex bits that can drill about 54" through an opening.

4) GFCI. No, it justs allows you to plug in a 3 prong plug.
A surge proector will protect against line to line spikes, but not line to ground unless generated by the equipment plugged into the protector.

5) Whole house. No comment.

6) sheathed cable test as grounded - Yes

7) Just not allowed. Don't know the code section.

I hope I answered your questions.

1: You can/should ground to the water pipe for the main ground within 5' of it entering the building. If it's 30' away, so be it. It acts as your grounding electrode and you don't need a ground rod.

what you cannot do is ground an outlet to an Ibeam and another to another section of copper pipe.

Ahh, so as I understand it now the NEC section I was reading from is referencing acceptable ways to ground the main? Not acceptable ways to ground outlets?




2) No. All pieces of equipment share the same reference. It's not current carrying except in fault conditions.
So just for my own knowledge, would grounding to a water pipe, and then connecting that ground to the main ground, which is also grounded to an external grounding rod be bad? Or just redundant? If it's bad, what about radio transmitters that are supposed to have their own grounds (eg, connected to a antenna tower) that ground the radio now to the new grounding rod and to the power ground... (Sorry, I'm a ham so this one is making me curious now... )


3) New cable. There are flex bits that can drill about 54" through an opening.
If this was an absolutely essential run I'd be doing that, but as I can just put a two prong outlet or a GFCI back on there and be grandfathered into code, and use the computer somewhere else, it's not worth the $70 for the bit extender.


4) GFCI. No, it justs allows you to plug in a 3 prong plug.
A surge proector will protect against line to line spikes, but not line to ground unless generated by the equipment plugged into the protector.

5) Whole house. No comment.
2 parts... Will the whole house surge protector allow a computer/etc to be plugged into an ungrounded GFCI without risk of damage? My understanding was that computers needed the ground for additional things than a surge protector and if a surge happened, which would imply no.


6) sheathed cable test as grounded - Yes

Ok, thanks, now time to see if I can find it, it's not that I don't trust the tester... but... trust but verify I guess?


7) Just not allowed. Don't know the code section.

Anyone else reading this happen to know where I should look?


I hope I answered your questions.
Indeed you have, thanks!
-David

2) I believe ground rods must be at least 6' apart. The two rods would be connected together and then continued to the panel so it would be redundant. Can't have two wires and two rods to the bonding lug. A single wire is used. The wire leave the panel and goes to rod one and then to rod #2.

HAM: Not sure, but I would thnik that if you can get to the main panel that would be preferable for the cable ground. A ground rod to the tower would deter lightning strikes, so if the tower is not connected electrically to transmit ground you would be fine.

Check references for antenna grounding, because I'm not sure.
It's important to connect the ground block as close to building entry as possible.

I just put up a TV antenna and I haven't grounded the mast yet, not have I put a strap around the rotor to connect both masts together.

4) The computer is a hard one. Ethernet is transformer isolated. USB connects the grounds together. I'd be careful with USB devices with 3 prong plugs connected to a 3 prong computer. Dial up modems don't need ground either.

If you use a surge protector like an Isobar, make SURE all the equiment is plugged into it. Don't string a USB cable 25' and use another outlet. Use Ethernet or wireless You will get line to line protection and should get some line to ground protection. Isolation transformers or say USB isolators if you were to rin 25' to a printer with a 3 prong outlet.

A main panel TVSS would be a good idea.

2) I believe ground rods must be at least 6' apart. The two rods would be connected together and then continued to the panel so it would be redundant. Can't have two wires and two rods to the bonding lug. A single wire is used. The wire leave the panel and goes to rod one and then to rod #2.

HAM: Not sure, but I would thnik that if you can get to the main panel that would be preferable for the cable ground. A ground rod to the tower would deter lightning strikes, so if the tower is not connected electrically to transmit ground you would be fine.

Check references for antenna grounding, because I'm not sure.
It's important to connect the ground block as close to building entry as possible.

I just put up a TV antenna and I haven't grounded the mast yet, not have I put a strap around the rotor to connect both masts together.

Both the antenna tower (some I've worked on are 90+ ft, so we NEED the ground) and the shielding on the coax are grounded, and preferably as close to the tower as possible, this is primarily for lightning, but also for a reference. But the shielding on the coax that is grounded at the tower is also grounded to the case of the transmitter, which is also grounded to the house ground, if I'm not mistaken.



4) The computer is a hard one. Ethernet is transformer isolated. USB connects the grounds together. I'd be careful with USB devices with 3 prong plugs connected to a 3 prong computer. Dial up modems don't need ground either.

If you use a surge protector like an Isobar, make SURE all the equiment is plugged into it. Don't string a USB cable 25' and use another outlet. Use Ethernet or wireless You will get line to line protection and should get some line to ground protection. Isolation transformers or say USB isolators if you were to rin 25' to a printer with a 3 prong outlet.

A main panel TVSS would be a good idea.

Sounds like the answer is to use the computer off a grounded outlet instead.


Thanks for your help
-David

There is a great deal to go through with this thread, not going to at theis time, but I have a few comments, not in any order.

You were correct on one method of grounding a no grounded outlet, going to metal water line and connecting no father than five feet away from the entrance of that water line.

I do not mention this exception for a couple of reason. The main reason is if you can run a ground wire from an outlet to the water line, then you can run a new branch circuit cable from the panel to the outlet. So why bother with this exception.

It gets too complicated in explaining how to qualify a water line as a grounding electrode.

Also, any water line being used as the main grounding electrode must be supplemented with a ground rod.

I am sure I am mising something, if so, get back with a list of issues.

craisis:

I'm going to hijack this thread for a few posts since there is no way of contacting you and I don't know of any HAM radio operators that frequent here.

This question relates to the HDTV switch and second edge difraction (2Edge) signal reception.

I receive nearly all of the signals via 2edge. Not line of sight, 1st edge or scatter. Some signals tend to disappear for a little while near dusk and reception gets poorer at night.

Tell me what you know about improving 2nd edge signals. Would stacking of antennas, or tilting of an antenna help the UHF signals. I knew of one tilt system, but it was discontinued.

Using the Wiengard HD8200U Antenna and a Channelmaster CM7777 mast mounted amp. Height is at least 30-40 feet. Most signals are, of course, UHF.

Also if you find anything about HAM antenna grounding post back.

I'd appreciate it. Thanks.