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Oil Boiler Isolation Switch.

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Evenin' All,


Regarding an external ground sited domestic oil fired boiler for heating and hot water that has an internal switched fused connection unit nearby inside the house, what regulations will require an external electrical isolator adjacent to the oil boiler? You know the sort of thing, a double pole rotary isolator. 


Z.


  • 0
    None.
  • 0

    Chris Pearson:

    None.




    Hello Chris,

                         it seems common practice to install them around here. I wonder if it is to offer a means of isolation in case of fire and the house is inaccessible?


    Z.

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    I would consider it better practice to install a local isolator, within reach of the boiler, not a specific regulatory requirement but good practice.

    And such an isolator MAY indirectly be required by the regulations, we are required to follow the instructions. All the boiler instructions that I have seen, require a local isolator.

    The exact wording varies but often includes "nearby" or "within sight" or "within arms reach"
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    so 510.3 if the MIs stipulate 

    132.15.201 if necessary to remove danger

    And possibly, if it has an electric motor, 132.15.202


    googling, in the US, code says an emergency shut off switch must be fitted outside the boiler room, or at the top of the stairs if the oil burner is in a basement
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    The boilers of this type I have wired may have a built in immersion heater and need their own 16-amp circuit.


    So generally from the internal SFCU or DP switch I run three core SWA with a core used as a CPC to the boiler main switch that is built into the boiler control panel, then bring a multi-core SWA back in to the controls wiring centre.


    If you turn the supply off at the boiler it disconnects both the boiler and the heating controls as it does if you turn it off at the internal SFCU/ DP switch which should avoid any nasty surprises without an external rotary isolator.


    The boilers with a built in back up immersion heater usually have a two way rocker switch making it a choice between running the boiler or the immersion heater.


    Andy Betteridge
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    Just as long as the FCU is capable of being secured if it can't be supervised by someone working on the boiler - most are these days - but not all were. Also capable of breaking N as well as L if it's a TT system.

      - Andy.
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    AJJewsbury:

    Just as long as the FCU is capable of being secured if it can't be supervised by someone working on the boiler - most are these days - but not all were. Also capable of breaking N as well as L if it's a TT system.

      - Andy.




    Yes Andy, the switched fused connection unit is immediately the other side of the outside wall and can be controlled by anyone working on the oil boiler. Its fuse can be removed and it can be directly under the control of the person working on the oil boiler. There is a house door right next to the oil boiler and a window so that the switched fused connection unit can be observed at all times. The boiler engineer showed me an internal mains plug that can be removed inside the boiler casing to disconnect the mains supply when he is working on the boiler. I can see no real reason for an outside extra rotary disconnecting isolator switch next to the oil boiler, but the boiler installer's mate said that "their electrician" normally fits one. I can see no harm in fitting one but it is extra work and expense.


    Z.

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    OlympusMons:

    so 510.3 if the MIs stipulate 

    132.15.201 if necessary to remove danger

    And possibly, if it has an electric motor, 132.15.202




    There is no indication in the manufacturer's instructions to fit an external isolator. Any motor is safely encased and contained so is totally inaccessible by anybody as it is inside a substantial housing as the oil boiler is located outside the house. 


    Z.

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    If you put a padlock through the fuse holder of the spur its isolated and 100% under the control of the engineer. If its not in the instructions then there's no need as far as the regs are concerned as far as I can see
  • 0
    Some of the external oil boilers I have wired were installed by the manufacturers son, so when it came to asking for manufacturers instructions we had the manufacturer on speed dial. ?

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