Bath Bonding

Discussion in 'Electricians' Talk' started by Bumbling Diyer, Feb 3, 2004.

  1. Bumbling Diyer

    Bumbling Diyer New Member

    I seems like the bath in my flat isn't connected to the supplimentary bonding.

    The only plumbing connection to the bath is the (plastic) waste pipe - the taps are wall mounted above it. The bath is steel enamel.

    Is this ok? The flat was recently inspection and tested by a NICEIC inspector who looked at the bathroom bonding and didn't comment, so I'm guessing it's alright in this instance. Any thoughts?

    Thanks!
     
  2. lastword

    lastword New Member

    It doesn't need to be bonded. A totally isolated metal object is fine, earth bonding it actually increases your risk of electric shock. Read this for background detail: http://www.iee.org/Publish/WireRegs/EarthingPlasticPipes.pdf It's written by Paul Cook. He's secretary to the IEE/BSI Technical Committee who are responsible for BS 7671. So you could say he 'writes the regulations'.
     
  3. Sam Dingle

    Sam Dingle New Member

    Are the pipes to the tap bonded?
    My thoughs are that the bath should be bonded, tap water is a conductor and when your running the bath there will be an electrical path between the taps and the bath.
    In a fault condition the bath metal work could be at a different potential to the taps.
    and so if you touch the bath and the taps at the same time, ouch.
    The aim of bonding is to ensure all metal work is at the same potential and thus remove the risk of shock.
    I'd play safe and bond it.
    It'll only cost you a few quid if you do it your self.
     
  4. unphased

    unphased Screwfix Select

    lastword is correct. It is a common misconception that water in the pipe conducts fault current. It doesnt.
     
  5. The Trician

    The Trician New Member

    Depends upon how ionised the water is; how much minerals are present - electrolysis!

    Usually, I bond the bloody lot to make sure I haven't missed anything. Unless its SELV/PELV or something like that.
     
  6. Gotcher

    Gotcher New Member

    This topic does seem rather too complex, even though the subject matter and reasoning is really simple to understand!

    The situation I'm grappling with is a new steel bath where the taps are connected via long flexi connectors, these connectors are bound in nylon, not metal sheathing. The waste pipe is plastic, so there's no direct electrical connection to the bath.

    The learned opinions I've received about this situation advise that the bath shouldn't be bonded, which is fair enough. However there is an electric water shower pump hung on the wall about 6in above the bath, fed by copper pipes which are bonded (correctly) which run alongside and around the bath - these pipes are insulated from the bath via plastic conduit. In the conduit also runs the power cable for the pump.

    My take on this has been that the bath ought to be bonded because of the possibility (remote or otherwise) that there might be a breach of the electrical cable or other pipes. But I can understand the alternative suggestion as well.

    Confused residing in the UK!

    Gotcher
     
  7. Damocles

    Damocles New Member

    water in pipes counts as an insulator, so long as the insulated section is long enough. 1m of plastic pipe is probably long enough. 1 cm is not, would count as already poorly earthed so bath should be bonded. 10 cm might be an insulator, depending on the quality of the water. clear as mud. But see other posts with links to discussions about this
     
  8. Screw-It-All

    Screw-It-All New Member

    BS7671 (IEE Wiring Regs 16th Ed) is clear about this point. All exposed conductive parts and extraneous conductive parts (i.e. all metal parts) should be connected by supplementary bonding (see 601-04-02). This is confirmed in Guidance Note 5 Protection Against Electric Shockand in the On-Site Guide which also state that connection back to the main earth terminal is not required. If you want to comply with BS7671 then do what it says and ignore the mostly irrelevant answers that you've been given by others.
     
  9. lastword

    lastword New Member

    Engineer, for the avoidance of doubt, where you including my post on this thread in your 'mostly irrelevant' comment?
     

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