House voltage varying up and down

[EddieWalker]

Great thread and replies. I've never dealt with this or even heard of it before, so it's really nice to get the information before I might need it!!!!

Eddie

 

[Dr Dave]

This happened to me 5 years ago, came home from Xmas trip and house was cold, some lights were bright and some dim. this fried the transformer in my furnace. The cause was the nuetral corroded/burnt in two in the underground service from the meter pole to the house. Since I had 100A service, I decided to upgrade to 200A at this time.

Dave

 

[sdkubota]

Is there a neutral wire that comes down the street? I think that I've just got two high tension wires and the "neutral" is created at the transformer.

I believe the neutral wire is grounded at the transformer. Don't ask me to explain that.

 

[Bamaram]

I believe the neutral wire is grounded at the transformer. Don't ask me to explain that.

If you have two high tension wires coming down the street overhead one is hot wire and the other is a neutral. In your case both wires come down the riser pole and hit the pad mounted transformer. Off the secondary side of the transformer, you probably have what looks like a single cable, but is actually the hot line with a concentric neutral. This just means the hot wire is surround by insulators then the neutral wraps around the cable and another layer of insulation is put on. You can't see this inside your house panel box because it is stripped at the meter socket. You will always have a neutral with a hot line except in some very, very rare cases.

 

[Qapla]

You have to remember that even though you have two hots and a neutral feeding your house (each leg being 110/120v), the transformer only needs one hot and a neutral to accomplish this. The two hot legs of 110/120v are created at the transformer, as the feed to the transformer is considerably greater then 120v.

 

[sdkubota]

If you have two high tension wires coming down the street overhead one is hot wire and the other is a neutral. In your case both wires come down the riser pole and hit the pad mounted transformer. Off the secondary side of the transformer, you probably have what looks like a single cable, but is actually the hot line with a concentric neutral. This just means the hot wire is surround by insulators then the neutral wraps around the cable and another layer of insulation is put on. You can't see this inside your house panel box because it is stripped at the meter socket. You will always have a neutral with a hot line except in some very, very rare cases.

Thanks for the explanation.

 

[BeezFun]

Is there a neutral wire that comes down the street? I think that I've just got two high tension wires and the "neutral" is created at the transformer.

This is confusing. I believe your setup is just like mine, one of those wires is high voltage the other is neutral/ground. The high voltage wire (4800v I think) connects to our transformer, and the transformer outputs two wires that are the two legs of the 220v service that goes into our house. There is a third wire (the neutral) that comes off the transformer and it does the following:
1. It's connected to the neutral/ground wire on our pole that runs up and down the street and presumably goes back to the utility company.
2. It's connected to a braided copper ground wire that goes down the side of the pole and disappears into the ground.
3. It's connected to our house in the service panel.

The confusion is whether that neutral/ground wire that goes up and down the street should be called a neutral wire or a ground wire, and exactly where it terminates. I would say it should be called a neutral wire since it normally carries current, and I'm guessing it goes back to the utility company and terminates at the center of some fancy multiphase transformer. The braided copper ground wire that goes down the side of our pole doesn't normally carry current, it's there in case the neutral running down the street on the pole fails. So it's just like in my house where my neutral wire normally carries current back to utility company, but if it fails for some reason, I also have a ground that should carry the current. So it seems like every house ground, every pole ground, and every neutral wire in my community is all tied together. The grounds are probably much higher resistance paths for the current, so when the neutral fails they don't work as well and you get all these strange voltage levels, but at least it keeps people from being killed (hopefully). Anyway that's my best understanding of how it all works based on what I've read here and gotten from our utility company.

 

[Bamaram]

This is confusing. I believe your setup is just like mine, one of those wires is high voltage the other is neutral/ground. The high voltage wire (4800v I think) connects to our transformer, and the transformer outputs two wires that are the two legs of the 220v service that goes into our house. There is a third wire (the neutral) that comes off the transformer and it does the following:
1. It's connected to the neutral/ground wire on our pole that runs up and down the street and presumably goes back to the utility company.
2. It's connected to a braided copper ground wire that goes down the side of the pole and disappears into the ground.
3. It's connected to our house in the service panel.

The confusion is whether that neutral/ground wire that goes up and down the street should be called a neutral wire or a ground wire, and exactly where it terminates. I would say it should be called a neutral wire since it normally carries current, and I'm guessing it goes back to the utility company and terminates at the center of some fancy multiphase transformer. The braided copper ground wire that goes down the side of our pole doesn't normally carry current, it's there in case the neutral running down the street on the pole fails. So it's just like in my house where my neutral wire normally carries current back to utility company, but if it fails for some reason, I also have a ground that should carry the current. So it seems like every house ground, every pole ground, and every neutral wire in my community is all tied together. The grounds are probably much higher resistance paths for the current, so when the neutral fails they don't work as well and you get all these strange voltage levels, but at least it keeps people from being killed (hopefully). Anyway that's my best understanding of how it all works based on what I've read here and gotten from our utility company.

You are correct. The wire in question should definitely be called a neutral becuase it is designed and intended to carry some current for what is generically referred to as "stray currents" which can be caused by several scenarios but most commonly a fault in the system. The neutral is grounded at nearly every pole though ideally each pole would be grounded.

In the OPs case one hot wire and one neutral come down the pole because he has a pad mounted transformer not a pole mounted. Once the hot wire is connected to the tap in the transformer it is broken down into two seperate hot wire assuming his house voltage is 120/240 which is most common in the USA. If this isn't his current then we have another can of worms. The neutral comes of a tap in the transformer and those wires go underground to his house panel mounted on the side of his home.

 

[BeezFun]

In the OPs case one hot wire and one neutral come down the pole because he has a pad mounted transformer not a pole mounted. Once the hot wire is connected to the tap in the transformer it is broken down into two seperate hot wire assuming his house voltage is 120/240 which is most common in the USA. If this isn't his current then we have another can of worms. The neutral comes of a tap in the transformer and those wires go underground to his house panel mounted on the side of his home.

I am the OP and I have a pole mounted transformer. There isn't one hot wire coming down the pole, there are two, but I haven't been talking about them because I understand them. It's possible different components are used in different parts of the country, but my setup is typical around here. There is a pole mounted transformer that supplies neutral and two hot leads (220v) down the pole that go to a pedestal on the ground. The two hot wires and neutral then go via conduit to my meter service. The pedestal facilitates connecting multiple houses to the same point on the ground, I happen to share my pedestal with one neighbor, but that's because we're out in the country and they're aren't any closer neighbors. If we were in a subdivision it's not uncommon to have 4 homes on a single pedestal. As far as I can see the pedestal is just a way to connect multiple residences to one transformer without running a bunch of wires up the pole.

 

[BeezFun]

You are correct. The wire in question should definitely be called a neutral because it is designed and intended to carry some current for what is generically referred to as "stray currents" which can be caused by several scenarios but most commonly a fault in the system. The neutral is grounded at nearly every pole though ideally each pole would be grounded.

I talked to my neighbor about this, he's an electrical engineer who admittedly builds video cameras not high power systems, but he says the neutral wire isn't carrying stray current, it's carrying all the current that comes down the high voltage line back to the power company. That makes sense to me, I can't see any way we could have a working system with only two wires if all the current flowing in one wire wasn't flowing back in the other wire. If we had multiple phases running along the pole I could understand sending current back a different phase, but that's not the situation we have.