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  1. #1
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    Default Long term overvoltage protection

    I have a home in the West Indies that has twce in the last year had an overvoltage issue (twenty minutes+) due to the 110 conductors coming together for long periods of time. The first time I was there when it occurred I got a reading of 223.8 volts from a 110 receptacle. It was due to the service neutral in area separating at a poor splice and dropping across the conductors. the second time a tree fell onto the the the lines. I have done considerable research (shunt trips, purifiers, automatic transfer switches, relays, etc.) and cannot find anything that will sense properly or control long term overvoltage. After the first time I installed a Cutler-Hammer Ultra surge protector, the recent overvoltage fried one leg of it and any surge strips on that leg.
    I think it is a failure or indequacy of Jamaica Public Service to have the proper equipment in their system that is the root of the issue. I am meeting with them next week to discuss a possible solution. Any ideas on what a normal utility does to control the problem or something I have missed as far as protection for my home? Thanks for any thoughts about this. Ed

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    Last edited by Ed Bliss; 01-04-2010 at 12:00 PM. Reason: mispelling
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    Default Re: Long term overvoltage protection

    West Indies, you say?

    I'd have to come down there for at least 2 weeks to evaluate the situation. Can't do it from here. Brain frozen, mon.

    "There is no exception to the rule that every rule has an exception." -James Thurber, writer and cartoonist (1894-1961)
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    Default Re: Long term overvoltage protection

    Quote Originally Posted by Ed Bliss View Post
    It was due to the service neutral in area separating at a poor splice and dropping across the conductors.

    Possibly by making better splices?

    What you are asking is not unlike asking why American cars are not as well built as German cars, or as fun to drive as Italian cars.

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    Default Re: Long term overvoltage protection

    Quote Originally Posted by Ed Bliss View Post
    I am meeting with them next week to discuss a possible solution. Any ideas on what a normal utility does to control the problem or something I have missed as far as protection for my home? Thanks for any thoughts about this. Ed
    In Canada, we get trees across the lines every winter. Hot lines touch neutrals ocasionally, or 30,000 volts might hit a 120 line. We NEVER get overvoltage for more than a split second. The Power Authority should protect you and your home wiring with better circuit breakers. It is a simple concept.
    In fact it's caveman technology.
    The breakers are mounted on the poles like palm trees along the street and can be controlled with a stick.


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    Default Re: Long term overvoltage protection

    Ed what you describe is more likely the loss of the neutral with no short involved. If the neutral is broken on the SEC side of the main panel, shuch as a tree limb breaking the neutral. Your grounding conductor that is tied to the driven ground rod should prevent such high voltage at the 120v outlets by providing a path back to the xfmr.

    If the neutral is broken after the point where neutral and ground are tied together, shuch as at or to a sub-panel, you will have voltages close to 220v at many of the outlets served by the panel missing the neutral connection. This is a drawback to the requirement that neutral and ground can only be tied together at one point the SEC.

    (this should stir the fire!)


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    Default Re: Long term overvoltage protection

    Been over two decades since I enjoyed time in Jamaca, but IIRC not US standard (60 Hz) but 50 Hz.

    Opening of just one hot conductor on a 120/240 multiwire circuit can lead to over voltage on the remaining closed conductors such as backfeed on the neutral.

    Ya mon time for electrical inspection.


  7. #7
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    Default Re: Long term overvoltage protection

    After the first time in Oct 2008 I added an 8' ground rod to the system at the meter location and at the main panel as the original rods were only 4' and not well driven.
    Should I separate the neutrals and grounds in the main panel if possible?
    Thanks for your reply. Ed


    Quote Originally Posted by Vern Heiler View Post
    Ed what you describe is more likely the loss of the neutral with no short involved. If the neutral is broken on the SEC side of the main panel, shuch as a tree limb breaking the neutral. Your grounding conductor that is tied to the driven ground rod should prevent such high voltage at the 120v outlets by providing a path back to the xfmr.

    If the neutral is broken after the point where neutral and ground are tied together, shuch as at or to a sub-panel, you will have voltages close to 220v at many of the outlets served by the panel missing the neutral connection. This is a drawback to the requirement that neutral and ground can only be tied together at one point the SEC.

    (this should stir the fire!)



  8. #8
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    Default Re: Long term overvoltage protection

    Could this be as simple as a loose wire in a panel at a breaker or bus bar?
    Will an ohm meter help me find the problem?
    90% of the wiring is in plastic conduit.
    When I discussed the wiring during early construction, I asked if Jamaica when according to the NEC, the answer was yes. The problem was that was likely the 1909 NEC. Single pole switches on separate lights at a stairway, receptacles 12 yards on center, two receptacles in the kitchen, switches 64" from the floor and on it goes. I have repaired or changed a lot. I was there about every five weeks during the construction but still, some things got away from me. Ed


    Quote Originally Posted by H.G. Watson, Sr. View Post
    Been over two decades since I enjoyed time in Jamaca, but IIRC not US standard (60 Hz) but 50 Hz.

    Opening of just one hot conductor on a 120/240 multiwire circuit can lead to over voltage on the remaining closed conductors such as backfeed on the neutral.

    Ya mon time for electrical inspection.


    Last edited by Ed Bliss; 01-05-2010 at 11:50 AM. Reason: Clarifcation

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    Default Re: Long term over voltage protection

    Quote Originally Posted by Ed Bliss View Post
    Could this be as simple as a loose wire in a panel at a breaker or bus bar?
    Will an ohm meter help me find the problem?
    90% of the wiring is in plastic conduit.
    When I discussed the wiring during early construction, I asked if Jamaica when according to the NEC, the answer was yes. The problem was that was likely the 1909 NEC. Single pole switches on separate lights at a stairway, receptacles 12 yards on center, two receptacles in the kitchen, switches 64" from the floor and on it goes. I have repaired or changed a lot. I was there about every five weeks during the construction but still, some things got away from me. Ed
    Sorry for not getting back sooner, I've been splitting wood for the fire. Probably don't have a clue what I'm talking about in Jamaica .

    I can't speak for the loss of a hot leg causing high voltage as I can't get that to happen in my head. The question of separating the ground and neutral is a different story. Having the ground and neutral tied together is what can prevent the high voltage you experienced. The poor ground rod connections could have been the reason that the voltage was high even though ground and neutral were tied together at the SEC (main panel). The basic idea is that there has to be a path for current to flow back to the center tap of the transformer, be it a wire or the earth. With out this path any imbalance of load between the two halves of the transformer will result in a corresponding imbalance of voltage at the receptacles. i.e. transistor radio on one half and toaster oven on the other.

    If the problem has occurred since you drove new ground rods, or if you are concerned that they may, you should have a qualified electrician check the ground and neutral circuits. This should include checking the ground rod resistance as there may still be a problem that can only be found by measuring the resistance.


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    Default Re: Long term overvoltage protection

    Ed,

    When you lose the neutral, or have a poor connection, you lose the centering point for the relative voltage to neutral.

    The 120 volt / 240 volt service is really just a 240 volt service with a common center point (the neutral) which is used as a reference to obtain the two 120 volt legs (from the neutral) - there still is 240 volts across the entire service.

    The neutral serves to keep the center of the circuit at 120 volts to each leg. With loads applied to circuits with that centered common point, the volts will remain the same and the current changes.

    When the neutral is lost, the center common point is lost, and then the voltage is 240 volt across two loads (two loads normally intended to see 120 volts). Now, the voltage is free to fluctuate across each load and the current is free to fluctuate based on the total of the two loads placed across 240 volts instead of each load being placed across 120 volts.

    That means that one load could conceivably have 90% of the 240 volts with the other load having the remaining 10% of the 240 volts, which calculates out to 10%=24 volts and 90%=216 volts.

    You could easily have any voltage combination which totals to 240 volts. I have personally seen 186 volts and 54 volts with an open neutral, which changed as soon as the loads were changed.

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  11. #11
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    Default Re: Long term overvoltage protection

    I really appreciate the advice.
    I am going to contact JPS and have come out and check their neutral connections from their pole to our meter and the meter to our service cable.
    We have a main and two subpanels in which I will tighten all the neutral lugs. Also will do resistance tests throughout.
    Thanks for the help. Ed


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    Default Re: Long term overvoltage protection

    I really appreciate the advice.
    I am going to contact JPS and have come out and check their neutral connections from their pole to our meter and the meter to our service cable.
    We have a main and two subpanels in which I will tighten all the neutral lugs. Also will do resistance tests throughout.
    Thanks for the help. Ed
    I said before If I'm Recalling Correctly (IIRC) Jamaica Standard Line is 110V/50Hz (not 120V/60Hz as here in US or Canada) the power company website confirms this. Therefore your measured voltage at 223.8 V indicates more than just an open netural, because you should not get a full load (and certainly not more than a full load) on the remaining (split) phase conductor unless one of the loads on the other (half) phase side is a dead short from hot to neutral.

    223.8 V is more than double the 110V/50Hz stand. tol.

    Two distribution panels now introduced. Suspect some sort of improper tie-in, short, or arc; on a device, strap, or within a JB between conductors from both panels in the same circuit or box; crossed connections from two independant circuits or multiwire circuit, or similar wiring error such as a neutral to a switch loop, failure to break a tab on a combo device where two circuits are landing, etc.; and/or improper tie-in of neutral and egc at distribution panels or downstream.

    I found a website for the power company noted it recommended electrical wiring inspection annually by electrician. I wonder why, might be due to common problems with lightening, power distribution problems, rodent damages, marine climate, and other good reasons perhaps?

    Quote Originally Posted by Jamaica Public Service Company Ltd
    Proper electrical grounding and wiring of a building after construction or purchase is your responsibility. It is important to have regular inspection of the wiring to ensure that the required standards of safety and service are maintained. You should engage the services of a licensed electrician to inspect your property and carry out necessary repairs at least once per year.
    About the Jamaica Public Service Company

    About the Jamaica Public Service Company

    About the Jamaica Public Service Company

    It might be in your best interests to engage an electrician for an inspection and to circuit trace, and explore your damages, especially since you indicated early on possibly having to contact the Utility and possibly having a claim for damages to your equipment.


    Last edited by H.G. Watson, Sr.; 01-06-2010 at 10:29 AM.

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    Default Re: Long term over voltage protection

    223.8 V is more than double the 110V/50Hz stand. tol.
    H.G.

    H.G. It is not all that uncommon to find voltage readings of +/- 10%, even in the U.S. This can be due to accuracy of the meter or adjustment of the secondary tap at the transformer.

    The resistance of something like a toaster oven would look like a short when compaired to a digital clock on the other leg.

    Tie-in of neutral and ECG at sub-panels have been found by every HI and there has never been a report of high voltage at the receptacles.

    I still believe the most likely problem the op experienced was the loss of a neutral either back to the transformer or to the neutral buss of a sub-panel.

    Last edited by Vern Heiler; 01-06-2010 at 12:06 PM. Reason: Re-read shorted thing!

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    Default Re: Long term overvoltage protection

    I know that VH.

    Point was that measured voltage at 223.8 V indicates more than just an open netural, because you should not get a full load (and certainly not more than a full load) on the remaining (split) phase conductor unless one of the loads on the other (half) phase side is a dead short from hot to neutral.

    Pointed out not a 120/240 60 Hz distribution system in Jamaica - therefore its full load (PLUS) he's reading at a 110V 50Hz receptacle.

    Two distribution panels now introduced. Suspect some sort of improper tie-in, short, or arc; on a device, strap, or within a JB between conductors from both panels in the same circuit or box; crossed connections from two independant circuits or multiwire circuit, or similar wiring error such as a neutral to a switch loop, failure to break a tab on a combo device where two circuits are landing, etc.; and/or improper tie-in of neutral and egc at distribution panels or downstream.

    Since tracking down an intermittant opening neutral can oftentimes involve loading and testing the system live recommended consulting electrician.


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    Default Re: Long term overvoltage protection

    Thanks, again for the input. I just spoke with my caretaker in Jamaica that was there the day of the first problem. He remembers the voltage being 192 +/- volts fluctuating to 213.8 volts, not 223.8 as I remember.


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    Default Re: Long term over voltage protection

    Quote Originally Posted by Vern Heiler View Post

    Tie-in of neutral and ECG at sub-panels have been found by every HI and there has never been a report of high voltage at the receptacles.
    Sure there has. When inadequate ground bond at the SE coupled with loss of center tap at/from the transformer (open neutral). Everything metalic becomes electrified, and voltage runs throughout. Its one of the reasons it is so very critical to have good earthing at the SE. Whether you have two circuits landing on the same device or a multiwire branch circuit.


  17. #17
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    Default Re: Long term overvoltage protection

    Normal utility? FIX their equipment, and pay your claim. Also, your homeonwers' insurance may provide some relief.

    Long term, or as a protective measure? That's well beyond the scope of this forum, or any DIY solution. Time to hire an EE to design something. (He might find a large UPS system that can do the job). It won't be cheap.


  18. #18
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    Default Re: Long term overvoltage protection

    Quote Originally Posted by John Steinke View Post
    Normal utility? FIX their equipment, and pay your claim. Also, your homeonwers' insurance may provide some relief.

    Long term, or as a protective measure? That's well beyond the scope of this forum, or any DIY solution. Time to hire an EE to design something. (He might find a large UPS system that can do the job). It won't be cheap.
    Longterm, as in the length of time the overvoltage lasted. It was not a spike.
    I have contacted the Electrical Engineering Department at the Colorado School of Mines, they may want to help with the correction of the issue as a project.
    I arrived on the island late last night. So far I have determined that there are at least three poorly done splices (never saddle a dead horse) of the neutral in the JPS grid close to our home after the nearest transformer. I found out today that several neighbors were victim of the overvoltage problem as well.
    As soon as I am done sending this I will check the polarity and resistance of everything past our meter. I wiil post what ever my tests indicate.


  19. #19
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    Default Re: Long term overvoltage protection

    I am back in the States. I couldn't find anything as far as polarity, bad connections etc. in the home. I spoke with a friend that has a hotel about a mile away on the sea. The problem caused her to lose several computers and other electronics. We will, together, with many neighbors present our case to the utility.
    Thanks for all the replies, tips and knowledge.


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    Default Re: Long term overvoltage protection

    If their mains are fairly reliable but the neutral is frequently shorted or open, you could always just ignore their neutral and install an isolation transformer.

    If their service is completely unreliable you might need a voltage regulator. I installed a 23 kVA line voltage regulator in a school once where they needed reliable voltage for their networking and telecommunications equipment. It had 20 sealed lead acid batteries that allowed it to supply a constant 230V AC and 48V DC to connected equipment.


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    Default Re: Long term overvoltage protection

    Just curious....does the Utility ground their system at the transformer?
    As I've stated before, one of the reasons for a grounding electrode system is to stabilize the voltage and give the system a reference.
    Transformers do their work by induction and without a reference at both locations (xformer & point of use), they will fluctuate a fair amount.
    Changes in temp will further irritate the situation.

    I would agree that the huge amount of voltage variation talked about in your case would most likely be a loss of a grounded and/or neutral connection. My experience has shown it to be a high impedance connection, otherwise, one would expect to see 230 volts across.
    I have experienced on two occasions where the bolted connection on the xformer itself was the culprit.
    Bob Smit, County Electrical Inspector


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    Default Re: Long term overvoltage protection

    Quote Originally Posted by Corn Walker View Post
    If their mains are fairly reliable but the neutral is frequently shorted or open, you could always just ignore their neutral and install an isolation transformer
    This is good advice.
    When you lose the center tap to the utility transformer the rest all becomes one big series circuit. It seeems to affect everyone in the area so this is the likely problem.
    Installing your own isolation transformer across the utility 240 volts only,and doing your own center tap to get the 120/240 volts you want on the secondary side will isolate you from their problems.


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    Default Re: Long term overvoltage protection

    Update and extensive Utility work detailed on new thread by OP here (click link):

    http://www.inspectionnews.net/home_i...tml#post123086

    Where he says

    Jamaica Public Service has replaced the wooden poles with concrete poles, installed proper grounds, run a new system neutral, trimmed the trees, installed a new transformer and removed an illegal connection just down the road from us. Hopefully this will solve the problem with voltage fluctuations. ED



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