220 well pump with light bulb on neutral

Discussion in 'General Electronics Chat' started by mr_trot, Oct 15, 2017.

  1. mr_trot

    Thread Starter New Member

    Oct 15, 2017
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    Hi:
    I had to replace the main panel feeding a 220v water well.
    The old panel had a 2 pole breaker connecting the two hots
    and the neutral had a series light bulb in line to the neutral bar on the box.
    I eliminated the light bulb and now the breakers immediately blow.
    What was purpose of the in line light bulb and is this why it is now tripping?
     
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    I haven't come across two lines and a neutral but if there was a light bulb then it was there for a reason.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Normal in N.A. 240v with centre tap to provide 2x 120v lines.
    What is the water well? a pump?
    If so describe the pump.
    Max.
     
  4. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    I see, I haven't played with that.
    Albert in UK.
     
  5. tcmtech

    Distinguished Member

    Nov 4, 2013
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    Sounds like the motor has an internal short between the lines and the neutral so someone is cheating things to make it work.

    Unless you have more information for us to work with I have to suspect that the odds are your motors damaged and operating in a dangerous partial short condition and the light bulb cheat is the only ting that keeps it functional enough to work at all. :eek:
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Possibly the pump motor is 120V rated and the lamp is used as a voltage dropper from 240V?
     
  7. MrSoftware

    Senior Member

    Oct 29, 2013
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    Maybe check the pump wiring and see if someone tied one of the hots to the neutral.
     
  8. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    I have to disagree. Years ago I played a trick on my brother. The hallway light switch operated the hallway light. I took the switch out and put a dual switch / outlet (one switch and one outlet. I then wired it so that when you turned the switch on the light would come on. But when the switch was off there was 120 potential at the outlet. The problem with the outlet was that if you plugged a vacuum cleaner into it (as he always did) when you turned on the vacuum the light bulb would come on but the vacuum wouldn't. The vacuum acted like a conductor, like a pseudo switch. Laughed my silly bald head off when he couldn't understand why the light would come on when he switched the vacuum on. So putting a light bulb in to reduce voltage across a motor load wouldn't work.

    Here's my guess at what the light bulb was doing: I think it was there to indicate when the circuit was live. My 240 electric stove had lots of 120 volt lights on it. It would use one leg of the 240 and the neutral to get the 120 needed for the indicator lights. For whatever reason the breaker is tripping, I don't think it has anything to do with the light bulb. Unless the bulb was there to satisfy the needs of something like a GFCI breaker (Ground Fault Circuit Interrupter).

    The best way to prove whether the bulb has anything to do with the circuit operation is to put the bulb back in the circuit. If it works with the bulb then it is needed for some reason. But like I said, this is just guesswork on my part. I still think putting the bulb back and seeing if it operates normally is worth the try.
     
  9. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    For those curious:

    Hot out goes to the lamp and out via the neutral, which was not present in the box. Old house employing the older wiring system for lights called an "Interrupt" circuit.

    Joke Switch.gif
     
  10. mr_trot

    Thread Starter New Member

    Oct 15, 2017
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    Thanks for all the thoughts..... I think it was there to let them know the pump was running.
    Curious why the bulb wouldn't trip the breaker like when I hook the neutral directly to the neutral bar in the box.
    Hooked to the neutral bar it trips the 30 amp breaker instantly. Haven't tried putting a bulb back into the circuit
    just capped the returning neutral for now. Well pump puts out good and cycles properly with neutral disconnected.
     
  11. MrSoftware

    Senior Member

    Oct 29, 2013
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    That doesn't sound safe. The neutral should carry 0 current in a 220v circuit.
     
  12. mr_trot

    Thread Starter New Member

    Oct 15, 2017
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    Agreed. But I finally decided whoever put in the original wiring just utilized the 2 hots in the primary wire and then used the white wire
    to feedback from one side of the pressure switch to power a light bulb back at the box so they could tell when the pump was running.
    Lazy but safe.
     
  13. ebeowulf17

    Well-Known Member

    Aug 12, 2014
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    Sounds like most of the "neutral" was never a neutral at all, but rather a switched high voltage line used to drive an indicator. The neutral in their original setup was only a neutral from the buss bar to the light bulb. The other end of the light bulb got power from the pressure switch.

    If you think of it in terms of a light bulb in the "middle" of a neutral line, it all sounds crazy, because of course there's no middle - the whole neutral should be at the same voltage (within practical limitations.) If you think of it in terms of a pressure switch driving two outputs (the pump and the light bulb) it's not that weird.

    And, to the best of my knowledge, there's no issue with neutrals carrying current, only with grounds carrying current. As long as the current through the short length of neutral wire from the breaker box to the light isn't too much for the size of the wire (which a light bulb almost certainly won't cause to happen,) then it's electrically pretty sound.

    The downside of creative wiring like this is that deviating from normal color codings and wiring layout/routing schemes makes it harder for people in the future to perform service (as the thread starter has discovered!) ... and it violates code, etc.
     
  14. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    If the breaker blows when you connect what you believe to be a neutral to what IS a neutral bus bar then your assumed neutral is not really a neutral. I'd suggest you carefully check the voltage potential between this believed neutral and the REAL neutral. Report your findings. If you're finding 120 VAC then it's not a neutral.
     
  15. MrSoftware

    Senior Member

    Oct 29, 2013
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    The danger is that the neutral line really is your ground line. In the USA (well, Florida anyway..), neutral and ground are connected. So if you're only using the 2 hot wires to run the motor, then unless it is grounded some other way, the pump may be floating without a ground, and could be a potential shock hazard. Unless you're running 4 conductors and using the 4th for ground.
     
  16. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    No, not just in Florida. The NEC covers all 50 states. I don't know the code myself, but I'm aware that both neutral and ground go back to the same place. According to what I believe I know, a normal house wiring system is supposed to have a single hot (120 VAC) going to an outlet (for instance). there needs to be a return path - the neutral line. There are limits to how many outlets can be on a single circuit, that part I don't know, but these outlets can be daisy chained (one connected to the next and to the next and so on), and a third wire, the ground, is similar. The code is clear that the ground is NOT to be tied to the neutral anywhere but in the breaker box. This is so that if the neutral breaks somewhere, there's still another path back to ground.

    So if you connect neutral to neutral and you blow a breaker then there's something wrong with the circuit. The thread starter didn't say what else was connected to the light bulb, only that when he connected neutral to the other neutrals the breaker would blow. So there might be a ground fault causing that - or the neutral may in fact be hot.

    I can't begin to tell you how many times I've come across wiring that was done by some home owner who decided what his own code was. When I bought this house I discovered that all the three prong outlets had neutral and ground tied together so that when you plugged in the tester it indicated a good neutral AND ground, and that hot was in the proper place. BUT there was a break in the wires and he spliced them back together. Black to white and white to black. HEY! He figured, AC is AC. Well, maybe true 50 years ago, but with the advent of polarized electronics, that is no longer a safe assumption. So when I plugged my computer into one outlet and my printer to another, when I went to plug the printer into the computer BANG! I got a direct path from hot to neutral because the printer was on a properly wired circuit and my computer was on a reversed wired circuit, meaning the computer was CASE HOT, not Case Ground as it should have been.

    The moral of that story is that you have no idea what someone else did before you. I even found lamp cord in the walls in this house. And wires tied together without a junction box and without access. Hidden junctions is another taboo according to the NEC. I don't know if or how many other countries subscribe to the NEC. It may be National or it may be international. But yes, house wiring comes in two legs that make up 240 VAC, with a split (center tapped) neutral (or ground). At the pole the transformer is grounded, at the meter there's a ground, and the electrical box should also be grounded. Either leg to neutral or ground should give you 120 VAC. If connecting a wire that you believe is neutral causes a breaker to pop - either it's wired wrong or someone used the wrong wire color out of convenience. Or ignorance. The ONLY other thing I can think of would be a GFCI Breaker (Ground Fault Circuit Interrupter).

    Something is not right with that electrical wiring system. Either it was done out of convenience or it was a mistake. But it IS dangerous. It might be well worth your time, money AND LIFE to pay a professional to sort out the issue(s).
     
  17. mr_trot

    Thread Starter New Member

    Oct 15, 2017
    5
    1
    Thanks for all the comments, but I am secure with my results. The pump has natural earth ground and casing also.
    No neutral required for the 220 pump. Economical use of unused white wire is properly taped red at the well and
    inside the box. All is good.
     
    ebeowulf17 likes this.
  18. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I'm pretty sure you've got a winding shorted to neutral like @tcmtech said but if you're happy with that then ok, it's your call. Replacing a downhole pump isn't cheap. I am not sure how dangerous the situation Is. I doubt anyone would be electrocuted in the shower but stranger things have happened.
     
  19. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    Good is good enough. If that's what you require.
     
  20. mr_trot

    Thread Starter New Member

    Oct 15, 2017
    5
    1
    I checked the wiring... the isolated white wire is Not connected to the pump, just one leg of the feed off the backside of the pressure switch.
     
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