Garage GFCI shows 30 Vac Open Grd Neu...?

[toicy4ya]

Hi guys,

I need your help. Yesterday I noticed my electric door garage would not open. I checked the main GFCI in the garage using a Klein Tools GFCI tester and it read "30 Vac Open Grd Neu". Which I believe it means it is only pulling 30 volts and there is an open ground somewhere. Unfortunately, the reset button on the GFCI will not allow me to test it. It appears to be stuck. I believe this is a normal function if there is an open ground neutral wire. I performed the following steps,

• Replaced the GFCI receptacle and tested it but got the same reading "30 Vac Open Grd Neu".

• I checked the breaker using a volt meter. It read 120 volts which is good.

• I checked every impacted outlet using the same Klein Tools GFCI testers beginning with the one closest to the breaker panel. Unlike the initial GFCI tested, all the outlets showed, "30 Vac Hot/Grd Rev". (I believe a loose ground will also cause this, please correct me if I am wrong)

• Lastly, I opened every outlet receptical including light switches and verified that all the wires including the ground was tightly screwed to the receptical.

I do not know what else to check. I welcome any advice. I called an electrician, unfortunately the earliest appointment available is next week.

Thanks in advance!

 

[Snoonyb]

Start with the voltage, with your VOM, at the known 1st location.

 

[toicy4ya]

Thanks for your response. Can you please elaborate?

I mentioned previously,

• I checked every impacted outlet using the same Klein Tools GFCI testers beginning with the one closest to the breaker panel. Unlike the initial GFCI tested, all the outlets showed, "30 Vac Hot/Grd Rev". (I believe a loose ground will also cause this, please correct me if I am wrong)

It sure if this is the same thing?

 

[bud16415]

I’m not a pro, but have done some trouble shooting in my past.



One thing I have found with ground issues is that with age the connections in the main panel can need a re-torque. Take off the panel front and kill the power and just run down all the connections and see if some of them can use a little more.



I haven’t seen many wire nut connection fail that were ok, but there is always that chance.



From a trouble shooting viewpoint the first thing I would do if the panel trick didn’t resolve it is I would disconnect the garage door circuit and then retest. Dived the problem in half so to say and eliminate some of the possibilities. Then go outlet by outlet taking them off the circuit further eliminating things.



You could also run an extension cord from a working outlet to the door and temp wire it to make sure the opener is working ok when you have it disconnected.

 

[toicy4ya]

Thanks for your response. I think I would leave the tightening of the screws on the breaker panel for a professional. Im not too familiar with it.

I did use a volt meter to measure volts on the side terminals. The GFCI was reading about 24.4 volts all other outlets were reading as 0.03 volts. I already checked that all the wires were tightly screwed to the GFCI and outlets. Im stumped.

 

[Snoonyb]

You said you checked with a volt meter, that's is also referred to as a VOM, so, shut off the breaker, open, the known, 1st receptacle from the breaker, turn the breaker back on and check the voltage, with the VOM.

With those reading your have a broken connection somewhere, and it could be in the receptacle box that the door operator plugs into.

 

[bud16415]

Hopefully one of our pros will be along to comment soon.



Just to get all the information straight, the rest of your house is working fine it is just the circuit to the garage that’s messed up? You have checked the voltage at the GFCI outlet that is the first device that the rest of the garage feeds off of and between the black and white wire you are reading 24.4 volts? When you check between the black wire and the bare copper going to the green screw what do you measure? The rest of the outlets and garage door opener are feeding off the GFCI? Do they connect to the side of the GFCI labled LINE or LOAD? Are the garage lights on a different circuit from the opener and the outlets? I take it the lights are not dim? Do you know that the feed from the panel runs straight to the GFCI?



I gather that you are using a digital meter to measure these voltages? Digital meaning one that read out a number and not an analog needle that sweeps across a curved scale.



It sounds like you have low voltage feeding the garage and I’m not sure exactly how a GFCI processes low voltage when it passes it thru as a protected feed. I would think it is expecting something around 120 volts and not sure what it does if it sees something really low. If one of the feed wires was open of course you would read zero volts but if it had a poor connection causing high resistance that would drop the voltage. You could well be reading the 24.4 volts when there is no loads applied and the voltage would be pulled down to zero with a applied.

 

[toicy4ya]

You said you checked with a volt meter, that's is also referred to as a VOM, so, shut off the breaker, open, the known, 1st receptacle from the breaker, turn the breaker back on and check the voltage, with the VOM.

With those reading your have a broken connection somewhere, and it could be in the receptacle box that the door operator plugs into.

Thanks, I shut off the breaker earlier and opened the first receptacle box I saw to the left and right of the breaker panel. When I checked the volts using the VOM on the side terminals it read 0.03 volts as did all the other receptacles with the exception of the gfci which read 24 volts.

 

[toicy4ya]

Hopefully one of our pros will be along to comment soon.



Just to get all the information straight, the rest of your house is working fine it is just the circuit to the garage that’s messed up? You have checked the voltage at the GFCI outlet that is the first device that the rest of the garage feeds off of and between the black and white wire you are reading 24.4 volts? When you check between the black wire and the bare copper going to the green screw what do you measure? The rest of the outlets and garage door opener are feeding off the GFCI? Do they connect to the side of the GFCI labled LINE or LOAD? Are the garage lights on a different circuit from the opener and the outlets? I take it the lights are not dim? Do you know that the feed from the panel runs straight to the GFCI?



I gather that you are using a digital meter to measure these voltages? Digital meaning one that read out a number and not an analog needle that sweeps across a curved scale.



It sounds like you have low voltage feeding the garage and I’m not sure exactly how a GFCI processes low voltage when it passes it thru as a protected feed. I would think it is expecting something around 120 volts and not sure what it does if it sees something really low. If one of the feed wires was open of course you would read zero volts but if it had a poor connection causing high resistance that would drop the voltage. You could well be reading the 24.4 volts when there is no loads applied and the voltage would be pulled down to zero with a applied.

Yes, the rest of the house is working fine it is just the GFCI and outlets that are located in the garage that are affected.

There is only one GFCI in the garage. Once the GFCI is tripped, all of the other outlets are affected including the electric garage door. However, the GFCI is not the first outlet nearest to the breaker panel. The GFCI is currently reading 24.4 on the side terminals with a VOM. When I check between the black wire and the bare copper going to the green screw I measure 122 volts. I believe the rest of the outlets and garage door do feed off the GFCI only because anytime that GFCI trips all of the outlets shut off and I am unable to open the garage using the garage door switch. Unfortunately, looking at the receptacle I cannot determine which side of the GFCI (LINE or LOAD) they are connected to. Yes, the garage lights appear to be on a different circuit from the opener and the outlets. No, the lights are not dim. They are operating as they normally would. Unfortunately, I can't confirm if the feed from the panel runs straight to the GFCI.

Yes, I am using a digital VOM. Please let me know if you have any additional questions and thank you for taking the time to help me with this.

 

[Snoonyb]

There is a simple way of determining the correct wiring of 3 prong receptacles, and which conductor goes where.

Generally, conductors other than green and white are HOT conductors.

Facing the receptacle, with the ground stake entrance down, the slot on the right is the hot side, with the neutral, on the left, and this indicated where the associated conductors are connected.

With a GFI receptacle, the upper attachment points are the LIVE terminals, with the lower being the LOAD, points of attachments.

Here is a tutorial; https://www.leviton.com/en/products/residential/gfciafci/gfci

 

[mark3885]

I’m not an electrician but I would start at the panel and work out. Pull off the panel cover and check voltage coming out of the breaker and move down the line from there. Remove the GFCI from the circuit and see what you get. Just my 2 cents.

 

[bud16415]

Yes, the rest of the house is working fine it is just the GFCI and outlets that are located in the garage that are affected.

There is only one GFCI in the garage. Once the GFCI is tripped, all of the other outlets are affected including the electric garage door. However, the GFCI is not the first outlet nearest to the breaker panel. The GFCI is currently reading 24.4 on the side terminals with a VOM. When I check between the black wire and the bare copper going to the green screw I measure 122 volts. I believe the rest of the outlets and garage door do feed off the GFCI only because anytime that GFCI trips all of the outlets shut off and I am unable to open the garage using the garage door switch. Unfortunately, looking at the receptacle I cannot determine which side of the GFCI (LINE or LOAD) they are connected to. Yes, the garage lights appear to be on a different circuit from the opener and the outlets. No, the lights are not dim. They are operating as they normally would. Unfortunately, I can't confirm if the feed from the panel runs straight to the GFCI.

Yes, I am using a digital VOM. Please let me know if you have any additional questions and thank you for taking the time to help me with this.

I think we are getting some place seeing as how you are measuring 122 volts between black and the bare copper green screw and some lower voltage between black and white it says someplace the white wire between the panel and the GFCI has a poor connection. You have replaced the GFCI so we know it is not that connection so starting there work your way back removing wire nuts, re-twisting the white wires and eventually if you don’t get it removing the face of the main panel kill the whole house and torque the screws there. If it was past that point then it would be affecting the whole house.

 

[Ron Van]

Because garage outlets (including the door opener) need to be on a GFCI and some outlets inside the house don’t need to be on GFCI, I’ll bet they wired that circuit to some interior outlets first, then to the garage GFCI and then to the garage outlets.

You have determined that it is the white wire (neutral) that has a poor connection.

Turn off the circuit breaker for the garage outlets and see if there are any outlets inside the house (probably on a shared wall) that are affected. If so, it’s probably one of those outlets that has a bad connection for the white wire.

 

[bud16415]

It is really hard to know the history of the garage wiring. Even if we knew the year of construction it is anyone guess how the circuits break out. If the construction is fairly new it is a safe bet a dedicated run or two were made to the garage and the GFCI was part of the plan along with the door opener. If it is old construction and the garage maybe added or maybe the powered door added then it requires more trouble shooting.



I have often suggested people take a day and make a map of the house and all the electrical outlets and devices and at least identify what breaker controls what thing. Knowing how they are chained together is even better but if you know the first part it will help you figure out the second part. Hopefully there are no hidden J-boxes (not to code). They can become hidden with DIY remodeling of basements sometime.



IMO and I’m not a pro the most likely place for a poor connection like this to show up is in the panel and the reason I suggested going there first. We don’t know yet and maybe the OP can tell us. The house is wired with copper conductors? Aluminum is even more likely for this type of problem.

 

[Ron Van]

It is really hard to know the history of the garage wiring. Even if we knew the year of construction it is anyone guess how the circuits break out.

Boy…isn’t that the truth. Our current house was built in 1970 and added on to numerous times. The electrical has been upgraded as well. The circuits are pretty bizarre.

.I have often suggested people take a day and make a map of the house and all the electrical outlets and devices and at least identify what breaker controls what thing. Knowing how they are chained together is even better but if you know the first part it will help you figure out the second part.

Absolutely! I suggest making a spreadsheet to tape inside the CB box.

 

[PJB12]

Read with care the great advice that Bud16415 wrote in #4. It is helpful.

People mentioned above the possibility of a poor neutral connection. They are correct.
Having good voltage line to ground, but not to neutral almost verifies a poor neutral connection. De-energize the circuit so no arcing will take place. Do not ues until you correct the problem.

Do Not Bypass The GFI if the neutral is open. You may send higher than normal voltage to the devices after the missing neutral. (Line Voltage x square root of 3 is often seen if your house is fed from a typical corner grounded delta transformer.)

Getting Started-
Ensure that your testers are accurate by testing known good devices.

Do your tests with everything connected to the GFI or GFCI protected disconnected. (Upstream you can leave.)

Some Hints-
Assuming a GFI receptacle & not a GFCI breaker:
First, check that your wiring is correct. People mix up the line & load terminals. They also accidentally cross the neutrals.

Next, since you have 120 to ground on the line side at the device, test for 120 to Neutral on the line side (same hot side test point). If you do not have proper voltage Line to Neutral on the line side of the GFI receptacle, the neutral is open upstream.


Work Safely-
I'm not clear if this receptacle is fed from a sub panel in the garage or from a house panel. If it is from a sub panel, you can lock off the main in the house feeding the sub panel and work safely in the sub panel.
In either event, lock the breaker off if it is not in your sight while you are working. (Locks are inexpensive.)


Maybe-
I'm an industrial & distribution electrician, so my house garage experience is limited. But, here are some things you may want to check-
As Bud wrote, check torque on the screws. Things loosen over time due to heating/cooling while in use. Any non-heated
building is notorious for things loosening. (This is very good reason to have AFCI circuit breakers.)
Any heavy load, such as a heater, can also lead to loosening due to heat/cool cycles of the conductors.
Check for corrosion at device & bus terminals. If you have aluminum conductors, post that here for instructions.
Check for any strands on the neutral wire (if stranded) that might be touching something grounded.

I hope one of these good peoples' posts can help you get up and running soon and for free!
Paul

 

[robfnk]

retired electrician with a lot of experience trouble shooting. First thing I would do is turn off the circuit breaker and see what outlets in the house and garage are not working. 9 out of 10 times the problem is an outlet that has push in connections. ( they should be outlawed) and the outlet is probably working fine. By turning the breaker off and checking for non working outlets you can normally find the last outlet on the circuit that is working. As someone said it is probably an outlet in the house that is feeding the garage. If it's an outlet with the push in connections causing the issue throw it out and buy a decent outlet with side terminals. wire not the correct wires together, pig tail them to wire you outlet.

 

[PJB12]

Thank You RobFnk for posting a very helpful step-by-step that will help the original posting member work logically and save time!

Having not worked residential beyond "Government" jobs, I didn't even think of those dangerous push-ins. My house had them and before I could ditch them all, two arced and burned. Thank Goodness for metal device boxes.



While inspecting switches & receptacle outlets for push-in type, also wiggle each conductor gently back & forth an inch or two away from any type of device termination. (Push, Clamp or Screw)

In the limited residential "Help Me" work that I've done for friends, many times it is discovered that the solid conductor was nicked when stripped and went unnoticed. When it starts separating, you can get low voltage readings until it finally separates enough to arc or completely separate. (Heat-Cool cycles and vibration cause the nick to come apart.)

I've had people tell me that they wired the offending circuit many years before, yet it recently failed. Therefore, the nick can certainly cause problems later. If the separation is against the end of the insulation, it may go unseen until you wiggle it.


Also check for the presence of two wires under one device screw. (Or 2 in a clamp clamp that's not rated for two). This causes resistance, thus heating, thus eventual loosening.

I've seen this often. Sometimes one conductor comes off the screw, leaving the other loose. More resistance = More Heat = Lower Voltage. (Or arcing)



Please Lock The Circuit Off Until Fixed!
If the conductor is only partially separated, the ends still could be close enough to cause the low voltage that you are reading instead of zero (or millivolt) readings of a circuit with good integrity. This generally means electrons are restricted in their travel and resistance builds. Resistance = Heat. It could also mean arcing is taking place.

Paul

 

[toicy4ya]

Hi guys,

I appreciate everyones help. I wanted to give everyone a quick update.

The electrician stopped by today. As it turns out, there was a slightly burned neutral wire in the breaker panel that appeared loose. The electrician also noticed several other wires that were loose. I understand some of you recommended that I tighten the screens in the panel but to be quite honest with you, I wasn't comfortable doing it.

Long story short, he repaired the wire and tightened all the screws in the breaker panel. Problem solved.

Thanks again!

 

[bud16415]

Hi guys,

I appreciate everyones help. I wanted to give everyone a quick update.

The electrician stopped by today. As it turns out, there was a slightly burned neutral wire in the breaker panel that appeared loose. The electrician also noticed several other wires that were loose. I understand some of you recommended that I tighten the screens in the panel but to be quite honest with you, I wasn't comfortable doing it.

Long story short, he repaired the wire and tightened all the screws in the breaker panel. Problem solved.

Thanks again!

Alls well that ends well.



If your thread points out any one thing I would complement you on knowing your limitations and not going past them. It is good advice for everyone to follow.



Such a thread was a good learning experience for you as well as others that might have followed along and in the future when folks search on similar problems.



Those of us that post often enjoy thinking about this stuff and trying to help.



You wouldn’t believe how many times a poster leaves us hanging after they solved the problem so thank you for letting us know.



Lastly don’t be a stranger keep the forum in mind when something else comes up or just stop in and say hi or lend a hand when you can.