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Generator set up ideas wanted
Murf, I have a question. If I run a generator with a transfer sw. that does not break the nuetral then it can backfeed the neutral and cause a shock. In reverse of that if I don't have a generator and I turn off my main disconnect and do not break the neutral then I can get shocked in my own home. Tell me how it can work one way and not the other. If so, why do I not get shocked when I turn off my breaker to work on my house wiring?
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Generator set up ideas wanted
How can the current from a power co. not backfeed the neutral if all I did was turn off the breaker?
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Generator set up ideas wanted
We live in an underground home with concrete floors. Ok, I can understand that it can be unsafe to not break the neutral on incoming or outgoing electric power. I have an air compressor that when wired for 220v. at two other locations had about 30 volts on the air comp. it self. I could not run a ground from the comp. to the panel without poping the breaker. When I moved to my present location and wired it up I expected to find voltage on the comp. To my supprise I did not and then I grounded the comp. and it did not pop the breaker. The motor is a 220v single phase made in 1956. The only thing that I did different was to switch the wiring to reverse the motor because at my present location it ran backwards. I never have understood why switching the wires around allowed me to ground the comp. Should this be a new thread?
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Generator set up ideas wanted
I don't think the wiring in any of the places this motor has been used (4 that I know of with 3 different owners) were faulty. The person that owned it before me took it to a motor shop and they told him it was meant to be wired with two leads and not grounded. That would be a neutral and a hot on 115 and two hots on 230 which is what the motor is rated at. The motor or pressure switch has no provision for a ground. To reverse the motor you switch leads 7 and 8 no matter if it is wired for 115 or 230. Apparently it has never had to have been reversed before as it was obviously hooked to the same two phases to run, at least the motor wiring appereared to have never been tampered with. I put a 120v 40w bulb between the comp. and ground so I could tell if it was hot to ground when I turned it on. It never shocked me and I do not believe the wiring in any of the places it was used was wrong. All the places were wired to code. I have posted a question on a motor forum to see if anyone knows why this motor acts the way it does. I have wondered about this for years and been watchful of it as well to avoid a shock. I do not like ungrounded motors, etc. and the thought that a generator could cause a hot lead on the power lines is unsettling. I have the intention of using a standby gen. at my home/shop and the local power co. will be involved with the installation when I do it.
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Generator set up ideas wanted
I did not ground it when I used it in Missouri but when I brought it here to Ky I decided to try to ground it and everytime I grounded it to the panel it poped the breaker. Remember that I did not have to reverse the motor direction at that time. The voltage from the motor case to ground was about 30v. So, far a safety warning I put a 120v 40w bulb between the case and the ground wire. I knew the bulb would not light up untill there was sufficient amperage to overcome the resistance of the bulb and then I had better not touch the motor as that would indicate an internal short that could be dangerous. No one but my son and I were ever around the comp. The reason I did not pursue it when I moved here is because it is now grounded. It has an internal protection and a circuit breaker. What I do not understand is why I could ground it when I reversed the motor. That has been puzzleing me since I hooked it up this year.
I have posted a question on eng-tips.com and also sent a question to A. O. Smith motor corp. I will post the replys here.
Just so everyone understands, When the motor is wired to run in one direction the motor housing is hot and cannot be grounded. When it is wired to run in the opposite direction the housing is not hot and can be grounded.
Now, from past experience with motors if a winding is shorted to the case then it shows up no matter what direction or voltage it is wired for. That is why I don't understand this motor and have been carefull with it.
Currently it is wired for 220v and is grounded. If anyone is interested it is an A. O. Smith 2hp 1ph 115/230v motor model# C1224N4AAA. It is a large heavy motor.
I may disconnect all the wires and check them to ground but, in it's current setup it is safe and I have no intention of replacing it. If it shorts out as wired it will kick the breaker and I will be forced to replace it or have it rewound.
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Generator set up ideas wanted
You cannot change the direction of rotation on a single phase AC motor by reversing the line connections. That is, going from white/white and black/black to white/black and black/white for 120v motor or swaping the blacks on a 220v motor. You cannot swap one of the two blacks for a white on a 220v motor because it would only get 120v and would burn up the motor and if you grounded the now loose black it would be a short and blow the breaker. Now, if it is a DC motor reversing the line will work.
To change the direction of rotation in a single phase AC motor you must change the connections of the windings internally according to the chart on the side of the motor. If you are using a 3 phase motor then to change rotation you just swap any two wires of the three line connections.
A single phase 120v motor is running on one phase of a three phase system. A single phase 220v motor is running on two phases of a three phase system. A three phase 220/440v motor is running on three phases of a three phase system.
All residential power systems today are 220v two phase systems. That is, you get two legs of the 3 phase grid. Most people don't know or understand that a 220v motor is running on two phases. I suspect that if you get leg one and two of a system at one location and then leg one and three at another then the motor that ran at the first location will run in reverse at the other location. I have no way to prove this but maybe the power company could tell me and maybe not. I just had an idea. I will take a single phase motor wired for 220v to my last employer and try this out as he has 3 phase in his machine shop and report back. That may explane why it switched direction from one place to another. Also, NO, the wiring was not faulty at any of the locations it was used. I do have experience wiring machine controls and home and business wiring.
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Generator set up ideas wanted
Generators and transfer switches. I talked to the lineman that works my area and hooked up my home and shop and instructed me how he wanted the meter base and disconnects. 400 amp service with 200anp in house and 200amp in shop with a 200amp disconnect on each branch. I asked about using a circuit breaker type disconnect as mentioned in an earlier post and he did not like the idea but if it meets code he would have to accept it. I have not asked if it meets code but I will probably use a standard transfer switch if and when I set up a stand by gen. As to breaking the neutral, he said at one time Ky Utilities wanted to do that but it never happened. He said they ground every pole and neutral at that pole. For it to cause a voltage feedback most or all of the grounds would have to break and the lineman would have to grab the open ends of a neutral line that has voltage on it. He said it would only happen if the lineman DID NOT FOLLOW CORRECT PROCEDURES.
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Generator set up ideas wanted
That Damn compressor motor. I went to an A. O. Smith authorized repair shop and told him my problem. He checked with the factory for my motor and they have no info on it. I asked if I should bring it in to test. He asked is it running and I said yes. He asked is it grounded and I said yes. He said if it runs, makes no noise and is grounded it has no problem. When I got home I disconnected the ground and checked with a VOM. It read 14.7v. I reversed the rotation and checked the potential to ground and it read 21.7v. I touched the ground wire to the comp. during both readings and it did not kick the breaker. I wired it for the right direction and checked the ground and it showed a potential of 1.5v. What happened to the 14.7 I got the first time? Who knows and I don't care. Hooked up the ground and taped the leads and covered everything up. It runs, it's grounded, so what's the problem. It sure as hell won't shock anyone and it sure as hell runs. If it ever shorts out and blows the breaker I will have it rewired.
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Generator set up ideas wanted
Yes, but what really has me puzzled yet is where did the short go that would not let me groung it before. Like I said if it shows up now it blows the breaker and goes to the rewind shop. Also, I missunderstood the lineman when he explained earlier this year about single phase, two phase, three phase. He told me today that the 220v comes from a center tap transformer like an earlier post said. He said that two and three phase is available in residential if I can justify a need and they approve it. But it costs a lot more. Sorry, my mistake, I just misunderstood what he had told me when I inquired about a new service here last year.
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Generator set up ideas wanted
You will have to Bear with us while we determine if the bear was bearing down on the hikers for a meal to bearly sustain itself. Now, if the runners could bearly bear to stand up to the bear then they may be able to bear the encounter with the bear and have a bear story to tell their barely believing grandchildren. I don't think Murf had a dog in that bear fight, or was it a bear in that dog fight. What ever.
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Gas Generator Weather Protecti
12-18-2005, 22:08 
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