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Oil Tank.

Situation.

Double domestic garage. Inside at the rear is a large steel heating oil tank on blocks off a concrete floor at high level. A copper oil pipe runs down and underground across a passageway to the oil boiler in the house. Garage sockets and light TT earthed via a garage unit with a 30mA R.C.D. The garage earth electrode is about 1.5m from the buried copper oil pipe in the passage outside.

The house earthing system is TN-C-S. The copper oil pipe is main bonded at the house.

Are there any potential safety issues here?

Z.

 

  • unless you spike a hole the oil line with an electrode, all seems well. 

    The question I suspect you mean relates to the oil pipe being bonded to the PME earth in the house, and exposed in the garage. Even if it was not ‘bonded’ the earth would still be exported as I bet the boiled is class 1 and has a 13a plug.

    Unavoidable, but less of a hazard in a dry floored garage than in a puddle outside, and less likely to be touched by a passer by than a PME earthed street light. What is there is probably the the best you could do. I'd suggest not losing any sleep over it.

    Mike.

     

  • If the intention was that the garage should be a “TT island” then clearly it is not. The infamous PME lost neutral is, presumably, unlikely between the house and garage, so I would not worry about that.

    What does concern me is having the oil tank INSIDE the garage. IMHO, garages are for the storage of motor cars, although I do appreciate that my view may be out-dated. ?

  • Having the heating oil tank inside a presumably locked garage is a valuable precaution against theft. A neighbour has a garage like building specifically to contain oil tanks.

  • Mike has hit the head of the nail.

    The steel oil tank is situated next to a TT earthed tumble drier. No fatalities so far, but is the situation ideal?

    Z.

     

     

  • broadgage: 
     

    Having the heating oil tank inside a presumably locked garage is a valuable precaution against theft. A neighbour has a garage like building specifically to contain oil tanks.

    If this oil tank sprang a leak, the oil would flood the garage floor and then run down the sloping entrance ramp producing a skating rink for motorists on the adjacent road.

    Z.

  • On an EICR, I would give a code 2 for having two earthing systems in one building. There is likely to be a potential between the two under normal circumstances. 

    Regards,

    Alan. 

  • As Alan said you have two different earthing systems better to put the garage on the house earth and keep everything at the same potential. 

  • This is a good case for an insulated joiner in the oil pipe by the boiler. Easily done, then bond tank to TT system. It is also obvious that the Garage does not have to be TT, so bond the MET instead to the Earth electrode and oil pipe. Come on Z this is all very basic, or are you trying to teach us something? I assume that there is no water supply or it is plastic?

  • The steel oil tank is situated next to a TT earthed tumble drier.

    Presumably the TT installation is properly equipped with main bonding for all extraneous-conductive-parts within its remit - so including the oil pipe - if so then the proximity isn't an issue.

       -  Andy.

  • davezawadi (David Stone): 
     

    This is a good case for an insulated joiner in the oil pipe by the boiler. Easily done, then bond tank to TT system. It is also obvious that the Garage does not have to be TT, so bond the MET instead to the Earth electrode and oil pipe. Come on Z this is all very basic, or are you trying to teach us something? I assume that there is no water supply or it is plastic?

    Hello David,

                           I came across this situation while undertaking some work at the property. I wondered why the garage was TT earthed. I am in  no position to alter anything as I have not been asked to. I am interested in others' viewpoints of the situation, thus the original post. There are quite a few differing replies for something so basic don't you think? I don't know if an insulated joiner is allowed in a copper oil boiler feed pipe in a house.

    Z.