Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 59 replies
  • Subscribers 31 subscribers
  • Views 5088 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

bonding a short section of water supply pipe

wallywombat
In a victorian terrace house, a lead water supply pipe enters the damp cellar, runs about a meter along the wall to the main brass stopcock, then converts to plastic pipe before exiting the cellar to the rest of the house (which is likely to be a mixture of copper and plastic). The stopcock is a couple of feet away from the CU. Should the supply pipe be bonded? My feeling is no, but I'd be interested in other opinions.


While I'm on the subject, a more general question. Why must any bonding be done after the main stopcock? For example where the supply tees off immediately after the stopcock, is it better to bond one of the tees, or bond just before the stopcock? Where there is a long run of supply pipe before the stopcock, is it better to bond after, with a long MPBC run back to the MET, or bond it near the MET even where that's before the stopcock?
Parents
  • 0
    AJJewsbury:
    The diverted neutral currents can be conducted by the armour of the P.I.L.C. cable.

    Not where the steel armour is cut back - as it inevitable is before a cut-out in order to access the lead sheath to make the Earth connection - so for the first few inches at least all the current has to be carried by the lead.

    For a domestic P.I.L.C. service cable, the earth fault currents will be limited in size by the protective device, say a 30 Amp fuse wire. So the lead will not have to carry hundreds of Amps. as it may for a lead gas pipe.

    But we're talking diverted N currents rather than earth fault currents. I don't know of anything that prevents diverted N currents flowing in lead sheaths of supply cables just as readily as they can flow in metallic water or gas pipes. They're all likely providing metallic paths to neighbouring installations as well as the soil.


       - Andy.


    The video of old showed the steel armour being connected at a joint. I was referring to that underground joint where the armour continuity was maintained.


    I was talking about earth fault currents and the limited magnitude of them flowing in the lead sheath of a P.I.L.C. cable.


    Z.


     


Reply
  • 0
    AJJewsbury:
    The diverted neutral currents can be conducted by the armour of the P.I.L.C. cable.

    Not where the steel armour is cut back - as it inevitable is before a cut-out in order to access the lead sheath to make the Earth connection - so for the first few inches at least all the current has to be carried by the lead.

    For a domestic P.I.L.C. service cable, the earth fault currents will be limited in size by the protective device, say a 30 Amp fuse wire. So the lead will not have to carry hundreds of Amps. as it may for a lead gas pipe.

    But we're talking diverted N currents rather than earth fault currents. I don't know of anything that prevents diverted N currents flowing in lead sheaths of supply cables just as readily as they can flow in metallic water or gas pipes. They're all likely providing metallic paths to neighbouring installations as well as the soil.


       - Andy.


    The video of old showed the steel armour being connected at a joint. I was referring to that underground joint where the armour continuity was maintained.


    I was talking about earth fault currents and the limited magnitude of them flowing in the lead sheath of a P.I.L.C. cable.


    Z.


     


Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines