[saffle]

I've searched for an answer to my question(s) and gained some insight, but still need some help. 19th century house. A lot of BX with 2-prong outlets and about half electric late installation with plastic wire with ground cable. Main panel (circuit breakers) has ground rod, but to make it more complicated it used to be two family house, so I have two meters and two main panels. Discovered through surge protectors with led's that some outlets have no ground after installing three prong outlet and tying ground to metal box. Testing the metal boxes and bx back to known ground shows no connection. I thought connecting to phone company's ground rod just outside this room would be good idea, but I get no useable ground at all. Phone wires are no longer connected. Later read about concern of imbalance between various ground rods. Tried connecting to water pipes of hot water heating system, but I have a well and get no ground.
I suspect that there may be a disconnect somewhere between a bx cable and a junction box. Is this where to start trying to find the trouble?
When looking inside breaker panels should both neutral and the ground wire be connected to ground rod ? And ohm meter show 0 from ground rod to any plugs neutral and ground jack ?
If I test with an ohm meter and connect a long lead to the grounding rod or ground plug of good outlet and look for a disconnect by tracing bx wires would this be a good plan ?
In my search I found some junction boxes without covers in the crawl space. They are not attached and not near any combustibles, but feel this should be addressed as well ?

Final question is it logical to think that I can remove one meter by connecting those wires that feed the other breaker panel inside the house to the first meter ? The meters are side by side and very fat wires feed the breaker panel inside the house. The other meter feeds panel on other side of the same wall. I would hire electrician and coordinate with electric utility of course.
Thanks beforehand.

[tkrussell]

BX (AC Cable) is allowed to be used as an equipment ground, but heavily relies on every box clamp and connector for continuity. There may be only one clamp or connector loose in the circuit or cable run that is preventing continuity of ground back to the panelboard.

This may get confusing:
The phone ground rod should not be separate and must be connected to the system ground , which is the wire and rod(s) connected to your main panel(s). Then you will read volts from hot to ground at the phone rod.

The purpose of grounding electrodes , rods, water lines, etc, is to ground the system neutral, and create the equipment(safety) ground for branch circuits, either BX sheathing, bare wire in Romex cable, etc. At the first Service Disconnecting Means/Overcurrent Protection Device is where the system Neutral and grounding is done, such as your seems to be.

Since there are two panels, and I assume both have a main breaker in each, then the grounding is allowed to connect to both neutrals in each panel. Reading 0 ohms as you mention is exactly what you should have.

So seems most of your three wire outlets are grounded using the BX, so going box to box from the last grounded box to the next looking for a loose clamp or connector is in order.

Any junction box, and outlet, switch, etc, must have a cover, anywhere. The purpose of covers is to prevent sparks from spraying out in the event of a short circuit, no matter if there are combustibles nearby or not. Today there are none, tomorrow may be different. Sparks and short circuits don't know the difference.

Eliminating one meter may seem as simple as connecting the wire, however, the meter box will need to be changed out to a junction box, and wires will definitely be too short. The two gang meter may need to be replaced with a single meter socket equal in rating to both meters. You may find that a new service is needed to convert this over to a single metered service, really depends on what equipment is there now, and what can be done so a safe system is left.

[saffle]

Thanks for your answer, it is very helpful.
In order to fix this situation, as some of the wires are not accessible,
Would it be OK to run a wire from a verifiable ground on a junction box to the group of outlets that are missing a ground connection ? Then check if there are any other outlets still missing a ground ? Solve those by either finding disconnected bx sleeves etc. or running yet another ground wire ? I would think that first attempting to find disconnects in the bx would be preferable, since one would not want any gaps etc.

In regards to the two panels - the main breakers are located on the meter panel of each.
The panel that is located away from the meterpanel also has a main breaker.
Does making sure the ground and the neutral are tied together still apply ?

As to changing from two meters to one meter I will consult the power company.
The savings on converting to one account may not be worth the cost of new equipment and installation.

[tkrussell]

In order to fix this situation, as some of the wires are not accessible, would it be ok to run a wire from a verifiable ground on a junction box to the group of outlets that are missing a ground connection ? Then check if there are any other outlets still missing a ground ? Solve those by either finding disconnected bx sleeves etc. or running yet another ground wire ? I would think that first attempting to find disconnects in the bx would be preferable, since one would not want any gaps etc.

Any wire you add must only be temporary or for testing purposes, cannot leave intending to ground the outlets missing a ground permanently. All wires of a branch circuit must be installed and grouped together in an approved raceway method.

In regards to the two panels - the main breakers are located on the meter panel of each.
The panel that is located away from the meterpanel also has a main breaker.
Does making sure the ground and the neutral are tied together still apply ?

Sounds like what is called meter/disconnects, all in one package. Here is where the system neutral is grounded by connecting the grounding electrode conductor to an approved grounding electrode. So in the meter/disconnect the utility neutral, the two panel neutrals, the two panel equipment grounding conductors, and the wire going to the ground rod(s) all connect and are bolted to the metal can of the meter pack.

From that point on the neutral and equipment grounding are to be separate. You should see 4 wires going from the meter/disconnect to each panel, and there is one neutral bar that is not bonded to the metal can of the panel(s). Since the branch wiring is BX, you may not see a separate equipment grounding bar in the panels, since the connectors and locknuts tight on the metal box is the equipment ground connection.. If any Romex cables come back to the panels, no bare wires should be on the neutral bar, but connect to a separate equipment grounding bar that is bolted directly to the panel metal box.

As to changing from two meters to one meter I will consult the power company. The savings on converting to one account may not be worth the cost of new equipment and installation.

Exactly what should be done, but the utility may not tell you how to do the actual equipment conversion, and refer you to an electrician for advice. And your right, the only savings will be the monthly service change for each meter, usually $8-$10 a month. For a job that may cost $500.00 to $1000.00, the payback will take several years. The upside is if the building is ever converted back to two family, the electric utility is ready for two apartments.

[saffle]

I really appreciate the detailed answer and will have to digest the info and crawl around under the house to put into practice.
So the idea of running an extra wire for ground is not good !
The alternative then may be to disconnect this branch where I can no longer check if the bx connections are solid because it is not accessible and instead run a complete line from another junction or from the panel to this group. Right ?
I'd be attentive to the load factor...

You make a reference to "approved raceway method". I don't know what that means? My crawl space is criss crossed with a mixture of BX and plastic (terminology?), so it is not running grouped in any orderly fashion. Is that a problem should any of my planned renovation require inspection from authorities ?
I'm a bit worried about code becoming an expensive issue, since the house is DIY from 1860 on and I have no paperwork on anything. A search of town records only revealed a permit for enclosing a deck in 1951...

[tkrussell]

BX and Romex, most likely, the plastic cable you see, each is an "approved raceway" My point is that if you have a two wire cable assembly, a third wire to act as an equipment ground, or any purpose, cannot be added, it must be included in the cable.

The cables you see do not need to be grouped, only wires for a circuit grouped into one bundle, as a cable.

Your solution to install a new cable and abandon the existing will work fine.

Since you have an electrician taking care of the service, ask for a whole house inspection, looking for anything that is unsafe, and suggestions of anything new, such as added circuits in kitchen, GFI in kitchens, baths, basement, and garage.

A major upgrade to current code will only be required if any major renovations occur, such as opening any walls, additions, etc. and only in those existing areas the renovations happen.

But upgrading the items I mention will be to your benefit, even thou not technically required.

While your looking for loose BX clamps and connectors, be sure to check all connections to switches and receptacles, if you find any that are the pus in the back style, consider changing them to the standard wrap around the screw type, as the pus in are popular for loose connections.

Install covers on any open junction boxes, check the splices to be they are all tight and well insulated before covering, replace any missing or broken device covers on switches and receptacles. Most of what to look for will be common sense. And ,unless the place was wired so bad, then should not be too costly to make the system safe.