Main bondage

ultinator · Feb 8, 2013

Does main bonding in every circumstance always need to be under 0.05. main bonding in a house where the main water was moved has 10mm cable but resistance of 0.25 ohms!!>>

Chr!s · Feb 8, 2013

Geoffsd said:
Of course it is.

Of course it is?

Geoff, do you want to expand further and explain you touch voltage concept. It's very different to how I've been taught.

DJ Ovengloves · Feb 8, 2013

Some of the comments in this thread are absolutely frightening!

Geordie Spark · Feb 9, 2013

DJ Ovengloves said:
This thread is much duller than I was hoping. Anyone got the phone number of trading standards?

Aye ........... the thread title got me all excited for a couple of minutes too.

Heisenberg · Feb 9, 2013

D Skelton said:
Damn! I opened up this post with 'Bondage' in the title hoping for something else How dissapointed I am.

You should be reading '50 Shades of T&E' :ihih:

telectrix · Feb 9, 2013

i generally find 1.5mm singles are best for bondage.

Guitarist · Feb 9, 2013

telectrix said:
i generally find 1.5mm singles are best for bondage.

Silicone insulation?

telectrix · Feb 9, 2013

fur...

ultinator · Feb 9, 2013

from MET @ CU, (front of house) removed 10mm cable, then where the stopcock is for water (rear of extension of house) removed the 10mm cable there. The resistance of this between one end and the other is 0.25. ohms.

As i cannot see the run, nor is there easy access to where it may be, and the fact that there are 3 x 10mm cables at the MET I would like to think that it is one length of cable, but the resistance readings simply doesnt state that.

But the bonding continuity has been verified.

Gavin A · Feb 9, 2013

Is this not pretty simple?

the 0.25 ohms reading is not even in the ballpark of being vaguely acceptable for the multiple reasons given in this thread. Given that the incoming water pipe has been moved this would be a strong indication that when they moved it they jointed and extended the bonding cable to move the bonding point to the new incoming mains point, and the chances are that this joint is the cause of your high resistance reading for one reason or another.

If you were working for me I'd be seriously unimpressed right now tbh, stop dithering and get it sorted then move on to the next job, bonding of water and gas pipes is about as basic as it gets isn't it?

apologies if you're a trainee.

Guest55 · Feb 9, 2013

if the actual resistance value of the protective bonding conductors was of such great importance you'd think that IET electrical certificates of any format would require you to record these readings ?

but they dont........?
in fact they ask no more than to confirm connection with a simple tick box......
which for the most part can can be done visually and a poke around with a screwdriver.

one could then reasonably assume that by selecting the correct conductor size as per the relevent tables in bs7671 fulfils these obligations whether the actual resistance reading is 0.05 or 0.25 ohms.

just a thought........

Elmer BeFuddled · Feb 9, 2013

Even to this inexperienced oik, if I got a reading as you are, my 2nd step would've been to get the wander lead out and check the cable end to end, then, seeing as I was under the sink, between MET and pipe ~ MET and clamp.

tidyboiler · Feb 9, 2013

Geordie Spark said:
Aye ........... the thread title got me all excited for a couple of minutes too.

Jeez that's a novelty!!!............

MDJ · Feb 9, 2013

When I saw the thread title I too wondered what it was about and wondered if the Mods were up to no good having a laugh at us lol, I love these mis-printed threads, posted by a Iphone I bet lol.

Jonny66 · Feb 9, 2013

ultinator said:
from MET @ CU, (front of house) removed 10mm cable, then where the stopcock is for water (rear of extension of house) removed the 10mm cable there. The resistance of this between one end and the other is 0.25. ohms.

As i cannot see the run, nor is there easy access to where it may be, and the fact that there are 3 x 10mm cables at the MET I would like to think that it is one length of cable, but the resistance readings simply doesnt state that.

But the bonding continuity has been verified.

Hi Ultinator....bet you wish you'd not bothered with the test now and I bet you regret asking for advise on here......but you did and good on ya mate........10mm at 1.83 milli ohms per meter (measured end to end) suggests around 136m of 10mm cable (I know already stated)....now as this measurement was an end to end measurement then I'm sure you can see that there is something amiss here, unless of course the cable length is 136m long.......By the way I quite like Geoffsd touch voltage concept.....would love to hear anybody else's reasons why 0.05ohms is used as a recommendation...

And just out of interest, why is it every time I post, I have to copy it, because if it takes longer than say 2mins to post, I get logged out and lose what I've posted...confused? cos I'am

VoltzElectrical · Feb 9, 2013

This is my take on it after a phone call to a much more knowledgeable friend.

The 0.05 value is BETWEEN simultaneously accessible extraneous parts, i.e. a gas pipe and a water pipe next to each other. Take for example this was the case, but each pipe was bonded separately back to the MET. Then the two would have to cross bonded.

The figure of 0.05 is not the value that needs to be achieved from the MET to the bonded extraneous part.