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my surge protection 'cpd', such as it is...

psychicwarrior
Good morning all


I have obtained the following [I feel as the] 'best we can do for now' information from the DNO. They were helpful in my test case request for info.


"...address 1:

LV underground - 362m

HV underground to primary-  2000m

No Surge protection devices


address 2:

LV underground to substation - 110 m

HV UG from substation to HV pole is 823m then 301m 11kV overhead then 190m HV UG to the primary substation.

Distance to cable termination with surge protection device from secondary substation is 1124m (823m 11kV UG + 301m 11kV Overhead).  The nearest cable

termination does not have surge protection installed. ..."


In relation to the risk assessment equation variables dealing with distribution cable lengths  ie. the Lpal Lpcl Lpah Lpch, how would one fit the given values into the variables ?


For addr1, ignore the HV (e.g. use zero for Lpah Lpch),  then take Lpcl as 362 and Lpal as 638 ?


For addr2, i'm not sure on this one ?


Thanks for your input.

Habs


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  • 0

    psychicwarrior:




    gkenyon:




    psychicwarrior:


    Interesting re: the phone line concerns - perhaps all one can do, given it belongs to the phone company up to the master socket and is not BS7671, is advise the client that it too needs looking at and to contact the supplier to have it assessed - or can someone fit something themselves without messing with the master socket - will have to have a read. Then there is fibre (dependng on construction materials) to consider...Or is it really immune as one might think.


    Thank you all again.




    The requirement in BS 50174-3 (referred to from BS 6701 and BS 7671) is to fit SPDs "at all building entrances if the IT cable contains metallic cable elements, and where inadequate protective measures have been provided in the external IT network".


    ...



     

    Is this saying that if considering/provisioning SPD, 'we' have to do so for everything else too ; should we be inspecting Comms, IT/Data installation cabling and SPD equipment, as a result of the indirect link in 7671 in that case, after the point it becomes not-the-suppliers concern of course. If so, where would such findings get recorded. Maybe time for a new section in Special Installations.


     

     




    This might be a controversial statement. But I'm prepared for it (I think).


    Telecomms cabling is definitely within the scope of BS 7671, although you can't simply apply BS 7671 alone (see regulation 110.1.3) - so why do you use the term "everything else", if it's all part of the same electrical installation to BS 7671 ?


    The difference with surge protection for telecomms, is BS 7671 specifically tells you to use BS EN 50174-3 rather than 443, see Regulation 443.1.1 para before NOTE 5.


    If you have been contracted to work on the power circuits alone, then of course there's a contractual boundary here, but I think this is something that should be sorted out at contractual level in that case, up-front where possible.


    Certainly, I don't think you could claim to have installed SPDs in accordance with BS 7671, if you didn't address the telecomms in accordance with BS EN 50174-3. However, you could claim that you were installing SPDs for the mains power circuits in accordance with BS 7671, and you've advised that someone should assess the phone/broadband/cable TV (or MATV) etc. services



    There will be some benefit in installing SPDs only on the mains, but full performance can't be guaranteed in all conditions, and perhaps it would be advisable to make such caveats to avoid the complications of claims in a future overvoltage event. (Although insurers might take matters into their own hands and go for settlement rather than argument.)

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  • 0

    psychicwarrior:




    gkenyon:




    psychicwarrior:


    Interesting re: the phone line concerns - perhaps all one can do, given it belongs to the phone company up to the master socket and is not BS7671, is advise the client that it too needs looking at and to contact the supplier to have it assessed - or can someone fit something themselves without messing with the master socket - will have to have a read. Then there is fibre (dependng on construction materials) to consider...Or is it really immune as one might think.


    Thank you all again.




    The requirement in BS 50174-3 (referred to from BS 6701 and BS 7671) is to fit SPDs "at all building entrances if the IT cable contains metallic cable elements, and where inadequate protective measures have been provided in the external IT network".


    ...



     

    Is this saying that if considering/provisioning SPD, 'we' have to do so for everything else too ; should we be inspecting Comms, IT/Data installation cabling and SPD equipment, as a result of the indirect link in 7671 in that case, after the point it becomes not-the-suppliers concern of course. If so, where would such findings get recorded. Maybe time for a new section in Special Installations.


     

     




    This might be a controversial statement. But I'm prepared for it (I think).


    Telecomms cabling is definitely within the scope of BS 7671, although you can't simply apply BS 7671 alone (see regulation 110.1.3) - so why do you use the term "everything else", if it's all part of the same electrical installation to BS 7671 ?


    The difference with surge protection for telecomms, is BS 7671 specifically tells you to use BS EN 50174-3 rather than 443, see Regulation 443.1.1 para before NOTE 5.


    If you have been contracted to work on the power circuits alone, then of course there's a contractual boundary here, but I think this is something that should be sorted out at contractual level in that case, up-front where possible.


    Certainly, I don't think you could claim to have installed SPDs in accordance with BS 7671, if you didn't address the telecomms in accordance with BS EN 50174-3. However, you could claim that you were installing SPDs for the mains power circuits in accordance with BS 7671, and you've advised that someone should assess the phone/broadband/cable TV (or MATV) etc. services



    There will be some benefit in installing SPDs only on the mains, but full performance can't be guaranteed in all conditions, and perhaps it would be advisable to make such caveats to avoid the complications of claims in a future overvoltage event. (Although insurers might take matters into their own hands and go for settlement rather than argument.)

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