metal junction box bonding question

[jdsac]

What I have is 4 metal junction boxes in the attic that were installed to repair the romex due to a previous "handyman " tapping into & splicing to the romex in the middle of the run.

The romex in the boxes is the old style 2 wire, no ground.

The boxes are on more than one circuit.

Is it correct/ legal to run an exposed bonding wire from box to box terminating to a box that is grounded? What size wire would be correct?

If this is not correct, what would be?

Thank You for the replies!

 

[wyliesdiesels]

Are 3-wire NM-b/circuits extended off these 2-wire NM cables?

If so thats not allowed and should be corrected.

Yes, code has an exception that allows EGC/ground wires to be ran separate from the circuit conductor. Use #12 THHN not bare copper.

 

[jdsac]

No, it's 2 wire all the way. Wouldn't have been necessary to install the boxes
if the hacker hadn't pulled power in the middle of the run instead of taking time to do it correctly. Just tapped in & taped it- no boxes. Wasn't happy to find that.

I used metal boxes because I couldn't find any plastic j boxes- the ones I looked at said for in wall use only.

Thank You for the help- I just want it correct/ legal

 

[MTW]

By today's standards metal junction boxes are required to be grounded, as you surmised.
Even if the supply cables contain no ground wire.

Back when 2 wire NM-B cable was used and approved, the only boxes required to be grounded was the ones within 6' of sink basins. Only the boxes were grounded, no requirement for the 2 wire duplex. It was allowed to be a bare conductor connected back to the nearest cold water pipe, usually at the adjacent sink. Other areas weren't required to be grounded, sounds like what you have.

Once you inserted the metal box, today you have the need for the ground bond. If any of the down stream circuit extensions were done with a grounded cable assembly, then that also mandates that grounding conductor is connected to a ground source.

Choices-
They do make special splice fittings for this purpose for use on NM-B in exposed and concealed locations. Can be used inside a wall cavity or attic without a box. Not the most common part, probably a no go at the box stores. Probably smile at the price too.

Plastic enclosure are also available, as well as fittings. Eliminating the grounding requirement, providing everything is 2 wire.

Grounding to the nearest metal water pipe is still an approved method for existing cables without a ground conductor. Use a proper pipe clamp or strap fitting. Ensure that no plastic pipe is in the water circuit return path to the service. Metal pipes are fading in use and can be replaced with plastic in the future, so this nay not be the best solution, even if approved.

Grounding to another circuit is permitted, as long as the ground wire size back to the supply panel, is the same size or larger, than the largest circuit size of the group in consideration.

The best solution if possible, is just to replace the cables in question, or at least the section that is fed from the source. Can sometimes be near the same amount of work to replace it, as to run an external wire. This corrects the problem permanently and is preferred.

Too many options?

MTW Ω

 

[sberry]

We should really re read the rules for running a separate conductor, they are limited. But, why fuk with it if it is up out of the way.

 

[sberry]

I am not a fan of all this anyway, the right way is to run a new wire. The original one is already old and beyond its good service life,,, yes I know,,, but it really is. We just rewired a whole house for this reason, we had intended to do parts but then it was a mess, now its done and its new.

 

[wyliesdiesels]

No, it's 2 wire all the way. Wouldn't have been necessary to install the boxes
if the hacker hadn't pulled power in the middle of the run instead of taking time to do it correctly. Just tapped in & taped it- no boxes. Wasn't happy to find that.

I used metal boxes because I couldn't find any plastic j boxes- the ones I looked at said for in wall use only.

Thank You for the help- I just want it correct/ legal

I shouldve rephrased what i said about extending circuits.

Code doesnt allow extending a new wire(2-wire or 3-wire) off of existing 2-wire circuits period.

I agree with the others. Why not run a new circuit?

 

[Norcal]

NM-B was never 2-wire ,NM was, the-B means the conductors are rated for ninety degrees that change occurred around the mid 1980's.

 

[wyliesdiesels]

NM-B was never 2-wire ,NM was, the-B means the conductors are rated for ninety degrees that change occurred around the mid 1980's.

Im assuming youre referring to what MTW said in #4...

 

[Norcal]

Yes, chose not to do a lengthy quote.

 

[MTW]

Norcal, NM-B was never 2-wire ,NM was,

Ok, drop the -B then.
It's been so long since the change now, I didn't think to differentiate it anymore, habit I guess.

Does it affect the readability and understanding?

Since I don't work with it often, I looked it up. The article still calls it NM
But then in the informational note it, signifies that the NM-B designation is for the 90ºC rated conductors. Which the old 2wire stuff was not.

However it's still not rated to be used past it's 60ºC ampacity. The 90ºC is only to be used for derating purposes.

Not sure that any of that applies to grounding a metal enclosure though?

MTW Ω

 

[wyliesdiesels]

No it may or may not matter in this case.

However, i will often say to use THHN for an underground feeder.

Someone will quickly jump on me and say THHN isnt rated for wet location.

Then someone or myself will jump back and say most THHN is dual rated THHN/THWN....

The same goes for 240v. People will say 220v and in most cases it doesnt matter. But theres that one time where someone really is dealing with 220v...

Also, NM, which someone may still have as NOS(new old stock), isnt allowed to be used anymore. So in some regards the differentiation DOES matter!

*rant over*

 

[sberry]

Grounding to the nearest metal water pipe is still an approved method for existing cables without a ground conductor. Use a proper pipe clamp or strap fitting. Ensure that no plastic pipe is in the water circuit return path to the service. Metal pipes are fading in use and can be replaced with plastic in the future, so this nay not be the best solution, even if approved.

Grounding to another circuit is permitted, as long as the ground wire size back to the supply panel, is the same size or larger, than the largest circuit size of the group in consideration.

I believe they did away with this, they allow a wire from a single device back to the panel.

 

[wyliesdiesels]

I believe they did away with this, they allow a wire from a single device back to the panel.

Nope still allowed as of 2014. I use to work for a contractor that did grounding for this PGE program that did "free to the homeowner" grounding of appliance outlets in old houses.

 

[sberry]

For replacement of non-grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C). C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor (3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates (4) For grounded systems, the grounded service conductor within the service equipment enclosure (5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure If you use the water pipe, the connection must be within 5 feet of where the pipe enters the building.

This is similar,, maybe not exact but,\ I am curious, where does it allow using water pipe as a grounding conductor? Where does it allow it from another circuit?

 

[jdsac]

Sorry, I wasn't clear enough. The romex that was "tapped into" the existing romex was removed and replaced with new circuits.

The boxes are there to splice (repair) the original that was damaged by the hacker. The only thing going through these boxes is the original romex.

Thanks again, you have all been very helpful.

 

[MTW]

This is similar,, maybe not exact but,\ I am curious, where does it allow using water pipe as a grounding conductor? Where does it allow it from another circuit?

In the section you posted.

C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor

If you follow up on where it references 250.50 and continue on, like it specifies you will find this.

250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductor(s) or jumper(s), if installed.

So, if you ensure that the pipe is in the earth for 10' and it's electrically continuous, as I mentioned earlier, it is considered a grounding electrode. If it exists in the structure, it's mandated that it be connected as one of the required electrodes for the service. If it's good enough for grounding the service, it's good enough for a branch circuit extension.

Just because it meets the verbiage of the law, doesn't mean it's the best choice. The local plumber or handyman may come along later and install some plastic in there and defeat the whole thing (electrically continuous) and the owner or occupant will be oblivious to the problem. It could put the situation back to square one. Just because it's legal doesn't make it the best choice.

For your second question. "Where does it allow it from another circuit?"
I'm going to make that your homework assignment. You do this routinely and don't give it another thought. When you run multiple circuits in a conduit for example, and use the pipe as the ground return for every circuit, what allows this?

The code is a law book and not a how to manual. It does not describe every situation in detail or provide a one line rule that cover's every situation. This is why I stress that you need to try and understand the "intent" first, so that it may be interpreted for those situations that are not typical or normal. That's why you have a AHJ, to understand the scope and make interpretations.

The NEC code handbook can be a valuable resource for gaining insight into interpreting the NEC, that's what it's printed for. If your serious about getting a good understanding of the NEC, get yourself a copy for some self study. You won't regret it. Send a PM and I'll give a link for you.

MTW Ω

 

[sberry]

C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor

Where does that say you can connect to any water pipe you can find?
250.52 Grounding Electrodes.

(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductor(s) or jumper(s), if installed

This describes an electrode, still doesn't say anything about allowing a branch circuit ground connected to it.

So, if you ensure that the pipe is in the earth for 10' and it's electrically continuous, as I mentioned earlier, it is considered a grounding electrode. If it exists in the structure, it's mandated that it be connected as one of the required electrodes for the service. If it's good enough for grounding the service, it's good enough for a branch circuit extension.

This is your own half assed interpretation, still not a code quote.

For your second question. "Where does it allow it from another circuit?"
I'm going to make that your homework assignment. You do this routinely and don't give it another thought. When you run multiple circuits in a conduit for example, and use the pipe as the ground return for every circuit, what allows this?

Yes it does, it says the grounding conductor will be with the same cable pipe or raceway, again doesn't say any pipe or ground wire you can find.

 

[sberry]

Doesn't say any of that Another thing, they didn't write it based on what some contractor a guy worked for did.

 

[sberry]

Grounding to the nearest metal water pipe is still an approved method for existing cables without a ground conductor. Use a proper pipe clamp or strap fitting.

Show me somewhere it says this.
The code types are pretty fussy about "verbage" and they don't really leave it up to everyone to decide which parts they like.

The equipment grounding conductor of a grounding-type receptacle

They even used "a" which normally means 1.

 

[MTW]

sberry, This is your own half assed interpretation, still not a code quote.

And with that, I'll leave you to your own interpretation, whatever that is.
Check with your AHJ, maybe he can dumb it down enough for you to understand.

The code is a law book and not a how to manual. It does not describe every situation in detail or provide a one line rule that cover's every situation.

Starting with the definitions is good place to gain understanding...
Excerpt from the handbook, as suggested.

Enough said here.

MTW Ω

 

[sberry]

You need a refresher class pops.

 

[sberry]

I will agree that of most of you are sharper than I am and a better mechanic. You likely understand way more than I ever will. But the intent if you will is to insure an uninteruped path and they list the places it can go to, essentially the wire from the service to the electrode or the same piece of steel this is connected to.
They figure if you can get it there you probably could get it to the panel it came from and highly sujest from some commentary that its where its sposed to go.

It doesn't list heating duct, doesn't list water pipe or other electrically grounds from other circuits as far as I know,,,, granted my latest code book is 2002 but and its 10 yrs since I open it.
Some more nonsense. (B) With Circuit Conductors. By an equipment grounding conductor contained within the same raceway, cable, or otherwise run with the circuit conductors.
NEC HANDBOOK COMMENTARY;
One of the functions of an equipment grounding conductor is to provide a low-impedance ground-fault path between a ground fault and the electrical source. This path allows the overcurrent protective device to actuate, interrupting the current. To keep the impedance at a minimum, it is necessary to run the equipment grounding conductor within the same raceway or cable as the circuit conductor(s). This practice allows the magnetic field developed by the circuit conductor and the equipment grounding conductor to cancel, reducing their impedance.
Magnetic flux strength is inversely proportional to the square of the distance between the two conductors. By placing an equipment grounding conductor away from the conductor delivering the fault current, the magnetic flux cancellation decreases. This increases the impedance of the fault path and delays operation of the protective device.

 

[sberry]

Yes, the above are examples of a ground fault path, they do NOT list it as an acceptable fault return. A telephone wire could be a ground fault path as well as a gas line, metal building siding. None of these are listed as a place to ground a recept to.

. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor (3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates (4) For grounded systems, the grounded service conductor within the service equipment enclosure (5 pipe, the connection ) For ungrounded systems, the grounding terminal bar within the service equipment enclosure If you use the water must be within 5 feet of where the pipe enters the building.

Does it list any of those in here?

 

[MTW]

(1) Any accessible point on the grounding electrode system as described in 250.50

 

[sberry]

(1) Any accessible point on the grounding electrode system as described in 250.50

Read that again, says on the grounding electrode system and further defines it with the 5 ft rule. Any water pipe you can find is NOT part of the grounding electrode system.
The description allows it to be hooked in a place and a way it cannot become interrupted from further work, legal on the wire going to the rod, on the wire at uffer or water service grounding. If it cant go there it is to go to the panel buss.

 

[sberry]

Doesn't say that anything grounded is allowed or that anything metal is allowed.

The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor (3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates (4) For grounded systems, the grounded service conductor within the service equipment enclosure (5 pipe, the connection ) For ungrounded systems, the grounding terminal bar within the service equipment enclosure If you use the water must be within 5 feet of where the pipe enters the building.

Again, this is where they are allowed, this is different than a description of a metal pathway. In the quote of the description you posted above it includes phone sheaths, stucco wire, duct, describes the earth as conductive but doesn't make it a legal fault return path for a branch circuit.
250 describes the system, doesn't list any water pipe further that 5 ft in as part of the grounding electrode system. It is metal and should be bonded but it isn't part of the grounding system.

 

[sberry]

--------------------------------------------------------------------------------

(1) Any accessible point on the grounding electrode system as described in 250.50

As one said, its not one liners and needs to be read complete, if one only reads any accessible point then it means one thing but there are 2 more parts to that statement, grounding electrode system and where the description can be found. It doesn't list any possible ground fault path as acceptable to hook to.