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Static Caravan Problems.

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I was called out to a static holiday/residential caravan today. Nuisance tripping was reported. Apparently the electrics were reliable before the van was moved to a new pitch on the same sandy site. The van's consumer unit comprises 1 30mA R.C.D., a 32 Amp socket M.C.B. and a 6A lighting M.C.B.


The pitch permanent "hook up" point comprises a 30 mA R.C.D. and a 16 Amp M.C.B.


The lady has many high powered appliances, 2kW kettle, three 2kW+ room heaters, a 2.2kW coffee machine etc. The heating is normally by bottled gas.


The two R.C.D.s tested out fine, not over sensitive. But the van owner can not remember which devices tripped off over a period of time. Once the nearby brick supply building had to be accessed to reset something, but we were not allowed even just to look inside it today by the site owners. Very unhelpful.


Anyway, all appliances tested good, no faults. I presumed that the lady had plugged too many items in at once.                                                                                                                                                                                                                                                                Guidance note 7, page 58 Fig. 7.1 it shows 4 possible separate vans being supplied via a single  100 mA R.C.D.


So, looking at the possibility of nuisance tripping if 4 vans each leak say 20 to 30 mA, the 100 mA R.C.D. could trip off blacking them all out. Should a time delayed 100mA type be used? The Guidance note says that the 100 mA R.C.D. is chosen to discriminate with the pitch socket outlets R.C.D.s. But, if say 100mA was to flow from a van fault,  both the 30mA pitch socket R.C.D. AND the 100mA brick supply building could trip off together. This would then deprive a total of 4 vans of a supply.


Comments please.


Thanks,


Z.


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  • 0
    Kelly Marie Angel:

    Morning all how's it going? Sparkingchip i thought an ELCB was an RCD by another name? Or am I wrong?  


    Hello Kelly, an E.L.C.B. is an earth leakage circuit breaker. Here is a JW video about the now obsolete Voltage Operated Earth Leakage Circuit Breaker (V.O.E.L.C.B.).


    They normally tripped well before the installation earthed metalwork reached 50 Volts, say at 30 to 40  Volts max.


    The earthing lead and rod were essential to proper operation. The rods sometimes rotted away or the earthing lead was pruned through thus making the device useless. I still find working models installed but they are getting rarer nowadays.


    A family were receiving shocks from installation metal work in an old holiday chalet here. The V.O.E.L.C.B. had no reliable connection to its earth rod, so thus did not work. Very dangerous.

    https://www.bing.com/videos/search?q=youtube+JW+VOELCB&docid=608039490843982793&mid=E9C7C600CA59C2530BDFE9C7C600CA59C2530BDF&view=detail&FORM=VIRE



    Edit. Add, What JW fails to say is that if the very long metal undergrounf water pipe is connected as his diagram shows the 15 Amp immersion heater fuse will automatically blow thus quickly clearing the fault. The V.O.E.L.C.B. will still limit the installation Voltage to less than 50 Volts in any case.


    A big fault with them was that a fault next door causing a water pipe to reach say 3o to 40 Volts would trip off your V.O.E.L.C.B. which would be a nuisance.


    If the earth electrode was not positioned out of the resistance area of other buried metalwork say like the underground metal water pipe, the coil would be effectively shorted and would not detect the fault Voltage of up to 50 Volts.


    One good thing about the design of the V.O.E.L.C.B. was that the test switch confirmed the good condition of the device plus the earthing lead and earth rod as well. A break in the connection to the earth rod would not allow the device to trip if the test button was pressed with the Crabtree design.


    Z.


Reply
  • 0
    Kelly Marie Angel:

    Morning all how's it going? Sparkingchip i thought an ELCB was an RCD by another name? Or am I wrong?  


    Hello Kelly, an E.L.C.B. is an earth leakage circuit breaker. Here is a JW video about the now obsolete Voltage Operated Earth Leakage Circuit Breaker (V.O.E.L.C.B.).


    They normally tripped well before the installation earthed metalwork reached 50 Volts, say at 30 to 40  Volts max.


    The earthing lead and rod were essential to proper operation. The rods sometimes rotted away or the earthing lead was pruned through thus making the device useless. I still find working models installed but they are getting rarer nowadays.


    A family were receiving shocks from installation metal work in an old holiday chalet here. The V.O.E.L.C.B. had no reliable connection to its earth rod, so thus did not work. Very dangerous.

    https://www.bing.com/videos/search?q=youtube+JW+VOELCB&docid=608039490843982793&mid=E9C7C600CA59C2530BDFE9C7C600CA59C2530BDF&view=detail&FORM=VIRE



    Edit. Add, What JW fails to say is that if the very long metal undergrounf water pipe is connected as his diagram shows the 15 Amp immersion heater fuse will automatically blow thus quickly clearing the fault. The V.O.E.L.C.B. will still limit the installation Voltage to less than 50 Volts in any case.


    A big fault with them was that a fault next door causing a water pipe to reach say 3o to 40 Volts would trip off your V.O.E.L.C.B. which would be a nuisance.


    If the earth electrode was not positioned out of the resistance area of other buried metalwork say like the underground metal water pipe, the coil would be effectively shorted and would not detect the fault Voltage of up to 50 Volts.


    One good thing about the design of the V.O.E.L.C.B. was that the test switch confirmed the good condition of the device plus the earthing lead and earth rod as well. A break in the connection to the earth rod would not allow the device to trip if the test button was pressed with the Crabtree design.


    Z.


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