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 32 subscribers
  • Views 6325 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can 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
    sweating a joint onto lead pipe or cable is out of fashion, but is a pretty robust.technique.

    Electrically you need perhaps 5 or 6  times the CSA of the copper to be covered with solder to ensure that the fusing current is not an issue - so a 1mm core needs to be immersed in solder for a couple of mm of length (think of the outside of the area of the cylinder of contact, being pi times diameter times immersed length..)

    For mechanical reasons you normally need a lot more than that, and to stop it moving during soldering you would normally bind or clamp the parts. Fine wire bindings  used to be used to hold parts like tin plate covers  and got left submerged in the solder.

    The exception is electronics of surface mount components where the solder alone is the mechanical fixture, as the surface tension is high enough to do this, but contact  area to weight ratios mean this is not applicable to larger devices, or things like switches or terminals where external forces greater than the self-weight are expected, these remain through hole fitting.

    There is a parallel weight and surface tension thing with  small insects that means they can walk on water but elephants can't.


    The problems of unsprung clamps on lead is that the stuff creeps over time and works loose, and clamps fitted by unskilled hands for things like PILC, where the lead is much thinner than lead water pipe,  that the lead is torn or other cable damage is unwittingly caused, but this is a mechanical not an electrical concern, at least until the mechanical damage causes a short to a core.

    Mike.


Reply
  • 0
    sweating a joint onto lead pipe or cable is out of fashion, but is a pretty robust.technique.

    Electrically you need perhaps 5 or 6  times the CSA of the copper to be covered with solder to ensure that the fusing current is not an issue - so a 1mm core needs to be immersed in solder for a couple of mm of length (think of the outside of the area of the cylinder of contact, being pi times diameter times immersed length..)

    For mechanical reasons you normally need a lot more than that, and to stop it moving during soldering you would normally bind or clamp the parts. Fine wire bindings  used to be used to hold parts like tin plate covers  and got left submerged in the solder.

    The exception is electronics of surface mount components where the solder alone is the mechanical fixture, as the surface tension is high enough to do this, but contact  area to weight ratios mean this is not applicable to larger devices, or things like switches or terminals where external forces greater than the self-weight are expected, these remain through hole fitting.

    There is a parallel weight and surface tension thing with  small insects that means they can walk on water but elephants can't.


    The problems of unsprung clamps on lead is that the stuff creeps over time and works loose, and clamps fitted by unskilled hands for things like PILC, where the lead is much thinner than lead water pipe,  that the lead is torn or other cable damage is unwittingly caused, but this is a mechanical not an electrical concern, at least until the mechanical damage causes a short to a core.

    Mike.


Children
No Data

Community Rules & Guidelines