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Winter Electrical Problems at a Marina

  1. Dec 20, 2007 #1
    During the winter we have serious problems with our electrical system that is becoming dangerous.

    I don't know exactly what question to ask that could help us so let me give you some of the symptoms.

    We are a liveaboard community in the mid-Atlantic so it gets cold here. Most boats have 50 Amp panels. Some have 2 separate 50 amp panels (I am one of those.) During the early morning and evening when most are home, our breakers start popping, panels rattle, the electrical lines from the pier become warm and apparently some have overheated to the point of arcing and fire. I don't have to tell you how devastating a marina fire can be.

    A qualified electrical company has certified that all lines are to code and compliance.

    It's obvious that many boaters are adding space heaters during morning and evening and they are unaware that they are overloading the circuits heavily.

    Any suggestions of how we can get a handle on the usage? Is there an instrument that can test each boat for their particular maximum draw?

    Those in the 'know' here say it is a decrease in voltage that can fry compressors, motors, etc. and that the electrical utility should 'give us more voltage.' Is that a fault of the utility? Doesn't seem right to me--can they 'increase' it?

    If I can't solve the whole marina's problem, how can I best protect my boat and my appliances? I use a lot of electricity but I also have two 50amp lines and they seem to be balanced for load (i.e., 2 heat pumps, 2 heaters (occasionally), washer, dryer, stove, HW heater, microwave, stove, fridge, lights/TV, etc--generally balanced between the two panels.) In the wintertime I only wash or dry clothes during the day when there are fewer people in the marina and only wash or dry since they are on the same panel. (During the summer I can wash AND dry with no problem.) I have become adept at taking some appliances off line but occasionally I'm surprised and blow a breaker. I also have one new 220 heat pump whose electrical cord heats up occasionally if I forget to turn it off...I'm real uncomfortable with depending on touching the plug to see if everybody on my pier is home!!

    I would like to do a full audit of my own appliances and wonder if there is, again, a meter that I can get to determine each appliance's draw? What would I be measuring? voltage? wattage? ohm resistance? amps? I'm afraid I don't even know what question to ask.

    Thanks for any help.
     
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  3. Dec 20, 2007 #2

    jim mcnamara

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    Radio Shack has a clamp on ammeter for about $20. You want to measure the amps flowing thru the line to your boat. Generally if a service is rated for 50 amps, in practice a long duration load somewhat less than 50 amps (say 45 amps) is what it will handle safely.

    When a motor in an appliance is turned on, the load spikes for a second or two, then lowers. This means a 10 amp motor can draw 15 amps on startup, for example.

    You are interested in the current - amperes or amps for short. Each appliance has a label that states the amps it draws in constant use, not the startup amps, which are usually more. Light bulbs are Watt units - stamped somewher on the bulb - like 100W or
    60W. 100W in a 120 volt circuit is about 0.8 amps, 60W = 0.5 amps, 25W = 0.25 amps.

    Go to every clock, TV, cell phone charger, bilge pump, fridge etc. and look at the label.
    Add up all of the amps, plus all of the amps for lightbulbs.

    A note: do not assume because a Nintendo or a radio is turned off it uses no current, an appliance in standby mode is using a small current. For the sake of what we're doing assume .1 amps per vampire (that's what they are called) applicance when the appliance is "off". Unlugging it is the only way to completely turn it off. Some of these appliances do better if left plugged in however, so consult the user manual.

    Add this mess all up. Then you are going to have to turn off or unplug things when you start up your heater(s). Don't assume that because you are drawing 40 amps it is okay to start an 8 amp appliance on a 50 amp circuit - remember the startup thing.

    The other issue - which you did mention: There must be a service drop from the local power company to a meter on the pier or for the whole marina (or are you individually metered?) Either way, when everybody has every power panel near max, it may be possible that the service (the transformer actually) to the pier is underpowered for the load. If that happens you get a brownout - manifested as a voltage drop - everybody's lights dim. Extended brownouts will damage some kinds of appliances. The only solution personally for you is: turn off sensitive applicances - PC's, etc.

    This is really a problem for the marina owner, the power company and you guys using the power. They may need to upgrade the transformer. This will increase "voltage", among other things. The other issue is if you are an old area, like some places along the Chesapeake Bay, the infrastructure there is antiquated and the ancient transformer may be attached to many service drops. And so the cost will be large to upgrade it. Which means the power company is going to resist installing the new transformer unless the marina owner agrees to a new, proably higher, electric rate.
     
    Last edited: Dec 20, 2007
  4. Dec 20, 2007 #3

    berkeman

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    One important point to keep in mind about the current clamp ammeter -- It must be clamped on only one conductor at a time, to measure the AC RMS current in that wire. You cannot clamp it around a 2-conductor power cord (or 3-conductor power cord with ground wire) and measure the total differential current flowing. It doesn't work for that.

    But in your electrical breaker panel, individual wires will be exposed (after you remove the protective outer perimeter cover -- carefully), and you can use the current clamp to measure each branch's current by clipping onto the appropriate Hot wire at the panel.

    You should also get in the habit of measuring the AC Mains voltage with your voltmeter (again, please be careful). If the AC Mains voltage is drooping much under heavy load, then some appliances will indeed draw more current. Anything that uses a switching power supply (computers, etc.) will draw more current as the AC Mains droops. Resistive heaters will not.
     
  5. Dec 20, 2007 #4

    chroot

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    There's no way that a utility can (or even should) "give you more voltage." If you're overloading your circuits to the point where voltage drop becomes significant, you need to address it by beefing up the supply components to comfortably handle the load.

    I really think your community should invest in a qualified electrician to come out and examine the entire system. If circuit breakers are popping and wires are getting hot, then it's definitely not "up to code" for the load you're putting on it.

    - Warren
     
  6. Dec 20, 2007 #5
    I agree with chroot. It may take some searching, but you and your fellow lovers of the sea need to find a company that is qualified to diagnose POWER QUALITY issues. DON'T assume that just any electrician has the necessary equipment and know how to handle your problem. Some do, and some do not. Until you find some help, try to talk to your neighbors and see if some sort of agreement can be made to try to reduce your electrical
    usage during peak times. If each of you can turn off just a few unused items during peak times, it may really help.
     
  7. Dec 21, 2007 #6
    I think with the whole community adding space heaters (inductive coils essentially) the PF is getting too low and hence more RMS currents in the transmission line.
     
  8. Dec 21, 2007 #7
    Ok, I'm getting a handle on this: poll fellow users, get the Radio Shack meter, reassess my own use (almost done on this) and talk to marina owners.

    Now, I was all just fine until unplebeian's 'the PF is getting too low and hence more RMS currents'... Can you explain in more plebeian terms? I studied physics 40 years ago, but never took E&M so I'm lost. Exactly how does the PF and RMS impact the trunk line service to our pier. We are individually metered but our line serves maybe 4-5 piers making it about 40-50 liveaboards plus a small number of recreational boaters who may/may not have any electrical draw beyond an inverter to keep batteries charged for bilge pumps or small engine heaters in winter.
     
  9. Dec 21, 2007 #8

    chroot

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    Your heaters are probably resistive heaters, which means they don't change the power factor at all, and unplebeian probably doesn't know what he's talking about.

    I wouldn't even consider power factor here. Instead, I'd just measure the current through the wires going to each boat, add them up, and see what kind of power dissipation you're really dealing with.

    - Warren
     
  10. Dec 21, 2007 #9

    To generate that much heat to keep yourself warm would require large resistors which are wirewound resistors having high wattage Min 1500W. They are inherently inductive in nature and hence cause a pf or power quality problem as someone mentioned above.

    I'll be glad to know I'm wrong. No problem there. At least I'll learn something.
     
  11. Dec 21, 2007 #10
    Basically a low pf causes more reactive energy storage in the inductors. This means that although your wattage may be low, the actual Volt x Ampere may be high. This is a common problem, but all you need to know right now is that low pf causes more RMS currents.

    However, CHROOT, does not agree with my explanation. I may be wrong too, just giving my opinion. So wait and see what he says.
     
  12. Dec 21, 2007 #11

    chroot

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    I'm not saying they have zero inductance; I'm just saying it's a very small inductance compared to the real resistance. I'm also pretty sure the manufacturers of electric space heaters design them to have nearly unity power factor, though I'm not having any luck finding evidence online. Most of the websites I've found tend to label space heaters as purely resistive loads, though.

    Besides, with all of the other things running on these houseboats, I don't think a space heater's inductance is a large enough issue to send POWYCCommodor on a wild goose chase about power factor.

    - Warren
     
  13. Dec 21, 2007 #12

    chroot

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  14. Dec 21, 2007 #13

    russ_watters

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    That isn't quite true. There's "your circuits" that you actually own and then there's "your circuits" that the electric company owns (the incoming service). When a the electric company provides an incoming service, they do a calculation to size the service. Sometimes they are wrong. In addition, sometimes they overload their own services in the area, leading to voltage drops for the entire local grid. I have a client that receives 208 volt service in Camden, NJ and in the middle of summer, the voltage drops to 199. When we had my office at my boss's house, in the summer the house voltage would drop from 120 to 106. This problem could be either the incoming service (ie, the transformer in the street or wires from the street to the facility) being overloaded or the local grid being overloaded. We have another client (new) that gets about one power failure a week in a growing manufacturing area. Presumably, the local grid is overloaded.

    Anyway, you are right - POWYCCommodor, what you really need is to hire a professional engineer (or a really good electrician) to mount a recording wattmeter on the incoming service to the facility, as well as a few sub-panels that have breakers popping, to monitor the power situation. Then you can take that information to the electric company and tell them to fix it if, in fact, it is their fault (they are required by law to provide within 2%, iirc, of nominal voltage). If you find that the incoming voltage doesn't drop and you aren't tripping the facility's main breaker, then the problem is not enough capacity to/in the boats.
     
    Last edited: Dec 21, 2007
  15. Dec 21, 2007 #14

    russ_watters

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    Yeah, you're wrong. Even if the reisistors are kinda coiled-up, the inductive load is a very tiny portion of the total load. Fractions of a percent. Inductors in motors have hundreds/thousands of windings (and steel cores), a coiled-up resistor might have a few dozen. For all practical purposes, it is purely resistive. That's why it is much more common for power factor to be a problem in the summer.
     
  16. Dec 21, 2007 #15
    LOL Love it when smart people disagree!!

    One fact to solve the inductive vs. resistive heaters issue: My experience is that most use the small ceramic heaters with a fan that you can buy at places like Target, etc. They are very effective in small places and shut off if the boat rocks. Remember we are usually heating only one stateroom or salon at a time. I assume they are resistive though there are no red-hot coils visible. Some boaters might have the oil-filled heaters (very expensive heat for the amount of electricity you throw at it, IMHO.) Most power boats have the marine heat exchangers (with hoses in the water) that work until the river temp. get real cold (don't recall the temp.--we are a barge so we have commercial heat pumps.)

    There's not the ghost of a chance either the marina owner, District of Columbia, or the utility company will do anything unless we determine there is a safety problem and one of them is at fault (very doubtful.) Also, we are scheduled for massive waterfront renewal for the next 10-20 years. I have already set my mind to organize the boaters and get some consensus to modify our usage (keep unnecessary lights off, try to run one heater at a time, do your washing/drying during mid-day, use a table-top oven/microwave instead of your range oven when possible, etc.) If anyone can add to my etc. I would appreciate it--those are just off the top of my head as I assess my own individual use.

    Susan Carpenter, POWYCCommodore
     
  17. Dec 21, 2007 #16

    Danger

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    Hi, Susan. Welcome to PF.
    As to your 'etc.', you might want to look into LED lighting fixtures.

    You could also start an orgy club, and let body heat take care of things... :uhh:
    An orgy in a hot tub, with a bit of detergent, could serve as a washing machine.
     
  18. Dec 22, 2007 #17
  19. Dec 22, 2007 #18

    russ_watters

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    Just fyi, with the exception of heat pumps, electric heat is electric heat. If it takes 1000 watts in, it produces 1000 watts of heat. And getting more efficient lighting won't help, for that reason: a light bulb is essentially just a small electric heater, so if you reduce power consumption by switching out (for example) 10 - 100 watt light bulbs with 25 watt fluourescents, you'll need an electric heater to make up the 750 watt difference in heat.
     
  20. Dec 22, 2007 #19

    russ_watters

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    Tripping circuit breakers is a safety problem. That's what circuit breakers are for! So that's why you will want someone who is qualified to assess such things to find where the problem is, so if it is the fault of the utility company, you can force them to fix it. They'll be breaking the law if they don't.
     
  21. Dec 26, 2007 #20
    Commodore, the first thing I would check are the circuit breakers. If they look to be in good shape then I would measue current with an inducton ammeter (I am sure your electricians have one) and verify that the wire size agrees with NEC for the circuit breaker rating, both line and load. I would look for for corrosion, what was called in basic to wit "a dirty tee shirt", a common maledy where I work at a shore based facility. Make sure no wires are loose on the terminal strips. I can always find my problems with voltage, resistance and current measurements.
     
    Last edited: Dec 26, 2007
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