Grounding existing 2 wire no ground

[Core_d]

On a replacement install of an AH. the chassis is connected to the fault circuit conductor via metallic conduit. To appease the inspector we run a wire from AH chassis to a copper water pipe with the existing ground still attached. I see a problem with this, anyone else. What is code related to the subject?

[timebuilder]

That is not a code requirement.

The metallic conduit is an accepted ground fault path with the proper bushings and locknuts.

No wires need to be run to any pipes to ground the air handler cabinet.

If the inspector believes this is required, ask which code section specifies the use of such a conductor.

[Core_d]

Thanks timebuilder

[timebuilder]

Thanks timebuilder

Many inspectors are doing that job because they like the feeling of authority, so you have to choose carefully how you challenge what they say.

"Oh, that's interesting. Can you show me where that is a code requirement?"

[timebuilder]

Just to be clear...

What we are actually talking about is called "bonding."

That part starts with 250.90 (General) and 250.104 gives the requirements for bonding piping systems and structural steel.

Note that these bonds to piping are not coincidental to a piece of equipment; they are simply required, and are usually made somewhere near the service panel.

250.104 B explains that gas piping ("other metal piping") is also to be bonded.

If you run conduit to an air handler (or other utilization equipment) and you use the proper bushings and locknuts where required, the metal raceway IS an approved "low impedance ground fault current path" that connects the normally non-current carrying parts of the air handler and connects them to ground via the grounding bar in the service panelboard cabinet, and through the main bonding jumper and the grounding electrode conductor, to the grounding electrode, the last element in that chain of connections, and the one that is actually in contact with the earth in some approved manner, such as rebar encased in concrete, etc.

So, this chain of bond connections does indeed lead to "ground."

[timebuilder]

One more thing.

250.118 gives you a handy list of things that can make up the low impedance ground fault current path.

The first item is conductors (wires).

Items 2, 3, and 4 are:

Rigid metal conduit
Intermediate metal conduit
Electrical metallic tubing

...to make it easy

[Core_d]

Thanks again, I do not think this was done on behalf of one certain inspector, this is our lead installers standard practice when the ground wire is not run directly to the unit. I did point out that the unit was infact on the fault circuit already. I have no intention on changing his habits if no harm is done with this practice. My line of thought was this could be a code violation in and of itself. I have also been told by atleast 2 instructors that 2wire with a ground is now required. So im glad you have cleared this up for me.

[timebuilder]

With the conduits I described and correctly installed, you DO have two wires with a ground.

[timebuilder]

On a replacement install of an AH. the chassis is connected to the fault circuit conductor via metallic conduit. To appease the inspector we run a wire from AH chassis to a copper water pipe with the existing ground still attached. I see a problem with this, anyone else. What is code related to the subject?

Just for the record....

Describe for me the "conduit" you saw. A pic would be great...

[jtrammel]

On furnaces with flame rectifiers its imperative to have a proper ground to the furnace. I've had some that work fine for years with 2 wire and no ground then all of a sudden it starts locking out until a ground is run to the furnace. That's probably why the lead tech has made a habit of it.

[Core_d]

Just for the record....

Describe for me the "conduit" you saw. A pic would be great...

This is not the unit but same type of flexable metalic conduit ImageUploadedByTapatalk 21371328924.010817.jpg

[Core_d]

On furnaces with flame rectifiers its imperative to have a proper ground to the furnace. I've had some that work fine for years with 2 wire and no ground then all of a sudden it starts locking out until a ground is run to the furnace. That's probably why the lead tech has made a habit of it.

Thank you for the reply. That is a thread with in its self. I dont think that is the case here but ill be sure to keep you up dated if thats the case.

[timebuilder]

This is not the unit but same type of flexable metalic conduit ImageUploadedByTapatalk 21371328924.010817.jpg

Only certain types of that kind of cable are eligible for use as a grounding conductor.

Generally, what is shown in that pic is not suitable.

Glad I asked.

[timebuilder]

On furnaces with flame rectifiers its imperative to have a proper ground to the furnace. I've had some that work fine for years with 2 wire and no ground then all of a sudden it starts locking out until a ground is run to the furnace. That's probably why the lead tech has made a habit of it.

When a rectification circuit changes behavior, a ground may correct the issue, but the problem is IN the unit.

Just an fyi.

[Core_d]

Only certain types of that kind of cable are eligible for use as a grounding conductor.

Generally, what is shown in that pic is not suitable.

Glad I asked.

Im glad you asked too. If this is not acceptable a water pipe is?

[timebuilder]

Let me see if I can put this in proper perspective.

The reason that we bond piping in a house is in the event it becomes energized, it will already be at system ground potential, and it will assist in opening the overcurrent device.

It would be a departure from approved methods to intentionally USE a water pipe as an equipment grounding conductor as part of a planned installation of a piece of utilization equipment, such as an air handler.

First, I would replace that cable with enough MC with ground to reach a box that contains a genuine EGC, and connect to that conductor for the ground.

If that is not possible, I would consider extending a known good ECG from the closest location, securing that conductor to the outside of the armor.

In the event that an inspector wants a water pipe connection, I would make certain that listed clamps are used to secure the EGC to the pipe, and that the pipe is correctly bonded near the service, as well.

I would also work very hard to convince all involved about option one being the hands-down best choice.

[Core_d]

Ok, I was aware replacing with 2wire and ground was the best option. Eventually im gonna buy a copy of the NEC im sure you would be of great help trying to decipher it. Thank you.

[timebuilder]

Ok, I was aware replacing with 2wire and ground was the best option. Eventually im gonna buy a copy of the NEC im sure you would be of great help trying to decipher it. Thank you.

Because we all service and install equipment that runs on electricity, each of us should have a copy.

[timebuilder]

Only certain types of that kind of cable are eligible for use as a grounding conductor.

Generally, what is shown in that pic is not suitable.

Glad I asked.

Often, what is shown in the picture is old-school BX cable, the outer armor of which is definitely NOT acceptable for use as an EGC.

Some modern MC and AC cables are acceptable, and they are mentioned in 250.118 (8) and (10).

[Core_d]

Thats good to know