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Neutral/ground issue
I have a problem outlet that reads 30V (digital voltmeter) between
neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T |
Neutral/ground issue
This actually sounds strange, since if there is a leak from hot to neutral, it ought to feed back to other neutral wires which are tied in to it. But perhaps not, if they are not really making good contact, just close enough to leak a little current. Did you replace receptacle itself/ retest? After that, I'd say you have to trace branch. Can you see the most logical route for it to join rest of circuit? If not, you may just have to identify all devices on circuit, then by trial and error disconnect wires at one at a time, recap wires and turn power back on till you find where branch is fed from. Look for poor insulation, broken or defective devices. If still no luck, may be wiring itself- as you say, it's from 50's. Anyway, keep reading here- others may tell you how to find this more easily with meter- not my forte. |
Neutral/ground issue
"Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. have you opened the outlet and made sure it's wired correctly? i.e., the ground and neutral are not swapped? ground on outlet is green or bare? The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T |
Neutral/ground issue
On 5 Aug 2006 20:54:31 -0700, "Tuyen" wrote:
I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. Open neutral. Induced voltage. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T -- Mark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin |
Neutral/ground issue
"Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T Buy one of those test plugs that will show what is miswired or most likey open then replace the outlet. |
Neutral/ground issue
ToMh wrote:
"Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T Buy one of those test plugs that will show what is miswired or most likey open then replace the outlet. I don't see how that will tell anything not already known. -- The e-mail address in our reply-to line is reversed in an attempt to minimize spam. Our true address is of the form . |
Neutral/ground issue
Mark Lloyd wrote: Open neutral. Induced voltage. That would definitely explain zero voltages when breaker is off. And if I short neutral and ground there's only 0.06 mA flowing. So: given the induced voltages and wire guage is it possible to figure out approximately how far back is the break in the neutral wire? I removed the receptacle and am making all readings with the bare wires. Thanks for all the fast responses! -T |
Neutral/ground issue
Tuyen wrote:
Mark Lloyd wrote: Open neutral. Induced voltage. Digital meter are very high input resistance and can easily indicate phantom voltages. Neon lights are not as bad but also can indicate. Plug in receptacle testers also operate at very low current. If they indicate an outlet is bad it probably is. If they indicate an outlet is good it isn't necessarily. They particularly can't be relied on to test for a good ground. That would definitely explain zero voltages when breaker is off. And if I short neutral and ground there's only 0.06 mA flowing. So: given the induced voltages and wire guage is it possible to figure out approximately how far back is the break in the neutral wire? I don't thinks so. Look in other boxes with devices on the same breaker. It will probably be toward the panel. Likely possibilities are back-stabbed receptacle through connections (good idea to convert them all to connection under screw) or loose wire in a wire nut. bud-- |
Neutral/ground issue
"Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T When you have an open neutral then the voltage readings are unpredictable depending on what is connected down stream. For example a light bulb will connect hot to the open neutral. Even though the bulb will not be lit (switch on), you will get voltage in the open neutral via the bulb filament .. An outlet tester as someone suggested will not give correct readings unless you remove or turn off all loads on that circuit. Sometimes this is hard to do if you have direct wired or hidden stuff on the circuit such as smoke alarms, or a doorbell transformer etc. It is also possible that your neutral connection somewhere has a high resistance connection. Where the wires are loose and overheated, a carbon bridge may let some current through giving the strange reading. Kevin |
Neutral/ground issue
2nd thought, think it'sgot to be open neutral, as Mark says. Think I
was off the beam with that first post. So your looking for loose wires(white) as you trace that branch back, or back stabbed receptacles as said above. |
Neutral/ground issue
On 5 Aug 2006 20:54:31 -0700, "Tuyen" wrote:
I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T If this was me, I would go to the panel and check for all the neutrals being secured. It sounds like a floating neutral somewhere. IMHO, tom @ www.NoCostAds.com |
Neutral/ground issue
"Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. Sounds like an open or bad connection on the neutral. Look at all the sockets on that branch and see if the connections are tight on them. When dealing with digital meters it is often helpful to put a 10 watt light bulb in the circuit across the leads to see if you really have a voltage or it is is some induced voltage the high resistance meter is seeing. Also a resistor of about 2000 to 5000 ohms can be used to help eliminate the induced voltage effect. |
Neutral/ground issue
Tuyen wrote:
Mark Lloyd wrote: Open neutral. Induced voltage. That would definitely explain zero voltages when breaker is off. And if I short neutral and ground there's only 0.06 mA flowing. So: given the induced voltages and wire guage is it possible to figure out approximately how far back is the break in the neutral wire? In theory, yes, but you'd need precise information on, e.g., the resistance of all intermediate connectors that would probably require you to disassemble the wall boxes anyway, and in the course of doing that you'd probably uncover the problem. Plus, I think the calculation would be pretty inconclusive without measurements more precise than you'd be able reasonably to achieve. So I think the bottom line is that it's a good thought but impractical. I removed the receptacle and am making all readings with the bare wires. Thanks for all the fast responses! -T -- The e-mail address in our reply-to line is reversed in an attempt to minimize spam. Our true address is of the form . |
Neutral/ground issue
"CJT" wrote in message ... ToMh wrote: "Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T Buy one of those test plugs that will show what is miswired or most likey open then replace the outlet. I don't see how that will tell anything not already known. These are a cheap, and a easy way to verify that the outlet is wired correctly, and changing the outlet will more than likely solve the problem. |
Neutral/ground issue
"ToMh" wrote in message news:c5qBg.3463$qw5.1058@trnddc06... "CJT" wrote in message ... ToMh wrote: "Tuyen" wrote in message oups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T Buy one of those test plugs that will show what is miswired or most likey open then replace the outlet. I don't see how that will tell anything not already known. These are a cheap, and a easy way to verify that the outlet is wired correctly, and changing the outlet will more than likely solve the problem. Oh sorry, I didn't catch that you had already removed the receptacle. You say it's a branch circuit, are you sure about this, and that it's not just the last receptacle on the line? If it is a branch, do you know were the branch is. If it's wired to another receptacle, then that probably were the problem is, else it's in the branch. Hopefully it's not some hack job buried in the wall. If you can't find the branch, you may want to just open up each receptacle on the bus and look for a an extra set of wires branching off of that receptacle. |
Neutral/ground issue
ToMh wrote:
"CJT" wrote in message ... ToMh wrote: "Tuyen" wrote in message egroups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T Buy one of those test plugs that will show what is miswired or most likey open then replace the outlet. I don't see how that will tell anything not already known. These are a cheap, and a easy way to verify that the outlet is wired correctly, and changing the outlet will more than likely solve the problem. I doubt it, given the situation described. -- The e-mail address in our reply-to line is reversed in an attempt to minimize spam. Our true address is of the form . |
Neutral/ground issue
ToMh wrote:
"ToMh" wrote in message news:c5qBg.3463$qw5.1058@trnddc06... "CJT" wrote in message ... ToMh wrote: "Tuyen" wrote in message legroups.com... I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T Buy one of those test plugs that will show what is miswired or most likey open then replace the outlet. I don't see how that will tell anything not already known. These are a cheap, and a easy way to verify that the outlet is wired correctly, and changing the outlet will more than likely solve the problem. Oh sorry, I didn't catch that you had already removed the receptacle. You say it's a branch circuit, are you sure about this, and that it's not just the last receptacle on the line? If it is a branch, do you know were the branch is. If it's wired to another receptacle, then that probably were the problem is, else it's in the branch. Hopefully it's not some hack job buried in the wall. If you can't find the branch, you may want to just open up each receptacle on the bus and look for a an extra set of wires branching off of that receptacle. Oops, I responded too quickly to your previous post. -- The e-mail address in our reply-to line is reversed in an attempt to minimize spam. Our true address is of the form . |
Neutral/ground issue
On 5 Aug 2006 20:54:31 -0700, "Tuyen" wrote:
I have a problem outlet that reads 30V (digital voltmeter) between neutral and ground, Try with an analog meter, although not an FETVOM. 88V between hot and neutral and 120V between hot and ground. The outlet is on a branch circuit; it appears to be the only outlet on the branch. Other branches of the circuit show the normal 120V between hot and neutral. I shut off all the breakers at the panel except the breaker for the problem outlet. The voltage readings do not change. I then shut off the breaker for the problem outlet (all breakers now off) and the outlet now shows zero voltage between all wires. The voltages at the panel appear normal. Also: there is no continuity between ground and neutral at the problem outlet. This would suggest an open neutral, but what would cause the voltage differentials on the neutral wire if it was open? There isn't an obvious back load soure such as an appliance. I'm going to attempt to find out where the branch ties in, but it's a 1950's split level with pretty inaccessible wiring. I hate older houses... help! -T |
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