Ground path when checking voltage

[threeputt]

I have been trying to get my home as safe as I can but again I have an electrical question. The outlet was added three years ago using the older two wire romex. The heating and air people that did the install used this breaker to supply 120 volts to one thing. SI-1801 Centrifugal Tank Pump with shows this
132 gph Mains supply
120V ~ 60Hz - 85 W - 1.45A yet they connected it to a 30 amp breaker already in panel that used a # 12 two wire without bare copper ground. Just the old style two wire romex. It was already wired I assume years ago when someone else was installing a gas furnace and AC unit. . I guess they never check the size of the breaker. The outlet is bolted to the back of part of the ac and heat duct work using the metal box for outlet .

The used the grounded three wire outlet but no copper wire or anything was connected to the green ground terminal . Just bolted to AC duct like I showed in picture.
I use my red lead of meter and connect it to hot side of outlet and black lead connected to metal AC duct and I get 122 volts. There is a few large metal posts that was used to support flooring and even that shows 122 volts when I touch black lead of meter to metal post and red to hot part of outlet.
So is these supplying a ground path ? and is this safe.
I know the 30 amp breaker isn't correct because this pump only shows drawing 1.45 amps. This is the only outlet on the run from panel and its not bootlegged. The metal post only touch wood and concrete floor.
What I missing is this. Is my meter not the correct one. I used another older radio shack meter and got the same reading. 122 volts. Just the one thing connected to the outlet and nothing else in between outlet and panel.

​

 

[RandyJ]

The AC unit chassis is probably connected to ground. Is the metal AC duct continuous all the way back to the AC unit?

I suspect your AC duct is connected to the metal chassis of the AC unit which is connected to a ground wire, .. apparently it is connected to ground enough for you meter to read 122V. Depending on the load on the grid, that voltage will probably vary a little.

Apparently the metal posts are connected to ground enough to get the same reading. I wonder do the post go through the concrete into the ground. You might try checking the resistance, (or for continuity), between metal duct and ground, and metal posts and ground.

Probably better to check for voltage between those metal pieces and ground first and proceed to the resistance test only if the voltage difference is very close to zero.

I'm not a pro electrician but most #12 gauge wire should have a max of 20 amp breaker,
(although some 12 gauge wire is rated over 20 amps).

20 amp breaker is usually max breaker size for 120v circuit. Depending on the exact 12 gauge wire you have it might be safer to have a 20A, (or smaller), breaker there.

(Edit):
I just checked and can confirm that the surface of the concrete in our garage is grounded enough for my meter to read 120V with one lead in the hot side of an outlet and the other leads' tip on the concrete. The reading varied from spot to spot but I did find a spot that gave a 120v reading.

 

[RandyJ]

(Adding to previous post):

When I put a little drop of spit on the concrete it reliably gives a reading over 120V. I checked the resistance between the wet spot on the concrete and the ground connection on the outlet, it started out about 16K ohms and quickly rose to about 55k - 60k ohms.
With this meter it doesn't take a solid ground to get a voltage reading over 120V.

 

[BillK]

I think you need to get an electrician in to wire it properly.

 

[BreeStephany]

If the supply wire is 12ga with no OCP between the breaker at your panel and the HVAC unit, the breaker at your panel must be rated for the OCPD used, which would be 20A.

I definitely agree with others comments. Sounds like you need to get an electrician to run properly rated conductors, a properly rated OCPD and to ensure that the HVAC unit, especially any equipment which may have contact with water, are properly grounded.

I highly suggest you contact a few licensed electrical professionals and get some quotes to fix this!

Just my two cents.

 

[Norcal]

HVAC "techs" touching electrical, they have no business doing it because they know just enough to be dangerous.

 

[alfredeneuman]

HVAC "techs" touching electrical, they have no business doing it because they know just enough to be dangerous.

^^^ This ^^^

 

[dave*99]

Typically, we see a gas furnace fed from a 20A or 15A circuit powering the controls and blower motor. So I suspect you must have some form of that in your system. I see a conduit in one of your photo, perhaps that is the feed I speak of.

Often, from that same circuit, there will be a receptacle installed. The condensate pump is usually plugged into that receptacle.

As to why an "unrelated" circuit was used to power a receptacle for a condensate pump,,,, no idea. Transitioning to the scheme I described at the top of this post may be an easy option. Then abandon use of the 30A breaker and receptacle entirely.

Do take a good look at what you have and be sure your description of the installed equipment is accurate.

 

[Duke74]

You could run a single, coated green wire to the box and receptacle, and bond it to your cold water pipe with a clamp.

 

[dcg9381]

You could run a single, coated green wire to the box and receptacle, and bond it to your cold water pipe with a clamp.

I didn't think this was allowed anymore.

 

[Duke74]

I didn't think this was allowed anymore.

I don’t know. We had a contract years ago to run bonding wires to interior wall receptacles in a bunch of houses. It was acceptable then, BUT that was 20 years ago. Might be best to ask your electrical inspector. If it is acceptable, it’s an easy fix.

 

[dave*99]

Bonding and grounding are very different.

Bonding keeps objects at the same potential. Grounding keeps a system at earth potential. And provides a fault current path.

Bonding conductors are separate from the current carrying conductors. Grounding (EGC) are part of the current carrying cable assembly.

 

[exranger06]

Part of the purpose of the grounding electrode system (ground rods driven into ground/ ufer ground/ whatever other electrode your building has) is to ensure that all grounded electrical parts are at the same potential as the literal ground you're standing on. So yes, checking the voltage between a hot leg and the concrete floor should give about the same reading as the voltage between a hot leg and an equipment ground.

This does NOT mean that the outlet is grounded properly. Voltage has nothing to do with current-carrying capability. An equipment ground needs to be able to carry enough fault current to trip a breaker in the event of a ground fault. This is why you need an actual copper conductor (or other suitable conductor) for the ground wire. This should've never been installed like this to begin with. I would rip out the old wire (or abandon in place if ripping it out is not feasible), run new wiring with a proper ground wire to the outlet, and install a new, proper, 15A or 20A breaker.

 

[threeputt]

The AC unit chassis is probably connected to ground. Is the metal AC duct continuous all the way back to the AC unit?

I suspect your AC duct is connected to the metal chassis of the AC unit which is connected to a ground wire, .. apparently it is connected to ground enough for you meter to read 122V. Depending on the load on the grid, that voltage will probably vary a little.

Apparently the metal posts are connected to ground enough to get the same reading. I wonder do the post go through the concrete into the ground. You might try checking the resistance, (or for continuity), between metal duct and ground, and metal posts and ground.

Probably better to check for voltage between those metal pieces and ground first and proceed to the resistance test only if the voltage difference is very close to zero.

I'm not a pro electrician but most #12 gauge wire should have a max of 20 amp breaker,
(although some 12 gauge wire is rated over 20 amps).

20 amp breaker is usually max breaker size for 120v circuit. Depending on the exact 12 gauge wire you have it might be safer to have a 20A, (or smaller), breaker there.

(Edit):
I just checked and can confirm that the surface of the concrete in our garage is grounded enough for my meter to read 120V with one lead in the hot side of an outlet and the other leads' tip on the concrete. The reading varied from spot to spot but I did find a spot that gave a 120v reading.

I am changing those breakers to 20 amp. The electrican that did this must have just put what he had in his truck

 

[threeputt]

Thanks to all who posted. I now understand how all this works. I turned the power off today and installed four new 20 amp breakers. I also ran a new 12-2 wire to the outlet that the pump was plugged in. It is now grounded with the green screw in the metal box with the copper wire. I am working on installing GFCI's outlets when I locate the one closest to the panel to finish my upgrades. Thanks for all the help.

 

[RandyJ]

I am changing those breakers to 20 amp. The electrican that did this must have just put what he had in his truck

I suspected that or that they were having an issue with a 20A breaker tripping frequently.

The house I lived in when I was young, (built in late 1950s or early 1960s), did not have ground circuits, just 2 wire for the 120V stuff.

I did not know this till recently, that three prong dryer circuits don't have a ground, they have two hot and a neutral like an old kitchen range style receptacle. Our "new" house, (built in 1991), has a dryer circuit like this, the dryer uses 120v and 240v.

 

[threeputt]

I suspected that or that they were having an issue with a 20A breaker tripping frequently.

The house I lived in when I was young, (built in late 1950s or early 1960s), did not have ground circuits, just 2 wire for the 120V stuff.

I did not know this till recently, that three prong dryer circuits don't have a ground, they have two hot and a neutral like an old kitchen range style receptacle. Our "new" house, (built in 1991), has a dryer circuit like this, the dryer uses 120v and 240v.

I did think about them using the 30 amp and why.

I found a bill where I paid the person $400 including 125 amp panel, wire, several new breakers and a few used ones to do this. Dated in April of 2005. He did run new 12-2 wire to my washing machine in basement and to upstairs where my computers are located.

After looking closer at the 30 amp breakers he installed all but these 30 amps look new even though its been 18 years ago. The 20 amps are a different brand also. My bet is he used what he had on the truck.

No breaker has tripped since I got them installed today.

I got a few more things I need to do but for now I call this completed.

 

[RandyJ]

Yes threeputt, since there were four of them, that is most the most likely explanation.
Sounds like you had a productive day.

 

[threeputt]

Part of the purpose of the grounding electrode system (ground rods driven into ground/ ufer ground/ whatever other electrode your building has) is to ensure that all grounded electrical parts are at the same potential as the literal ground you're standing on. So yes, checking the voltage between a hot leg and the concrete floor should give about the same reading as the voltage between a hot leg and an equipment ground.

This does NOT mean that the outlet is grounded properly. Voltage has nothing to do with current-carrying capability. An equipment ground needs to be able to carry enough fault current to trip a breaker in the event of a ground fault. This is why you need an actual copper conductor (or other suitable conductor) for the ground wire. This should've never been installed like this to begin with. I would rip out the old wire (or abandon in place if ripping it out is not feasible), run new wiring with a proper ground wire to the outlet, and install a new, proper, 15A or 20A breaker.

The shop floors in the area I work sweat a lot in the winter months but all those years nobody has been hurt. Not really for me because I am old but I sure my son will use the shop on occasion after I pass and I wouldn't want him in danger or anyone else that might be there. I have had two license electricians tell me it was safe. The problem is one told me it was safe to bootleg a ground at my home which I didn't do.

 

[dave*99]

If the wire is in metal conduit, the conduit is likely the ground path. You can use a ground pigtail connected to the outlet and a grounding screw inside the junction box.

There are also self grounding receptacles. They have a brass plate near 1 mounting screw:

 

[threeputt]

Yes threeputt, since there were four of them, that is most the most likely explanation.
Sounds like you had a productive day.

I did RandyJ. It was no problem at all. Got all the correct breakers installed .