For want of a better forum title I'm submitting here.
My son has a digital multi tester can I use this to test earth bonding and best way to proceed.?

Don't say get one of the free checks through elec supplier had two just to see if first differed from second, no difference, interest was more on Wylex wire type fuse fuse box..£800 to change open area no scrabbling in cupboard.The only cables to extend may be the tails from the meter outside on same wall backing the fuse box.

Bob, February 2011

Just an added thought - see that the word impedence was used in an answer. Multimeters are used to measure resistance using direct current ( a current that flow only one way - such as from a battery ). With mains electricity using alternating current ( a current which keeps changing it's direction of flow ) there is an additional effect which can take place to limit the current flow and this is reactance. The reactance and resistance will act together with ac to produce a combined effect called impedence.
For ac you can use volts = amps x impedence.
As an example the input connections of a transformer will offer impedence to ac current but only resistance to a dc current and will probably then burn out!
Look these up on internet for a more detailed explanation.

best wishes Nyge C, March 2011

I am not a qualified electician - I can only give you some comments as an electronics/physics teacher. With the size of wires and copper pipes involved in a bonding circuit the circuit resistance of the safety path will be low - I expect well below an ohm. Multimeters are usually used to meaure much higher resistances than this.
One way to measure such a low resistance is to use a high current flow test and this would need specialised equipment which is readily available at a price. So while a multimeter might suggest all is well this may not be the case.
A competent person with the right equipment is required. Find out what the regulations say wrt diy testing and go from there. Do not enter into false reassurance because it will be when a fault occurs that you will find out if the circuit is satisfactory ... it's like climbing without a safety rope!

best wishes Nyge C, March 2011

£800....jesus was he wearing a strippy shirt and a mask. you can get it done for half of that price

bidge, February 2011

you dont use a test meter to check earth bonding,
or cross bonding,what you do use is an earth impedence meter,we use this to check the entire earth system in the house,the lower the reading ,the better,0.8ohm is very good.earth bonding is the connection from the db to the gas or water pipe feed from outside,cross bonding is where you link the pipes together,like under your sink,boiler,etc,also if you get a new db fitted,you need to get a P.I.R.done on the electrical system,and a certificate obtained,

mm, February 2011

Brian hopefully your looking in.

Thanks! see where your going as there are idiots re-elec like the clown who wired up a front door lantern before we moved in our bungalow...twin internal flex outside no earth metal latern, dissed the elecs to fit new one [before part P] and found flex tape joined to 6amp wire which was plenty long enough to reach light so why ????? completely safe and earthed new lantern. I may be ammature or should say untrained [only do my own] but did re-wire my house including fuse board 20yrs ago when we lived in London, all passed.
Part P and Building control is the barrier Part P certificate and Building control will probably say NO can't do that. So it seems stick with what I've got or hope for affordable estimate. Other thoughts as a Wylex fuse board buying plug in mcb's from Screwfix to save having to wire up fuses or buyi set of spares.

bob, February 2011

two things amateurs shouldn't mess with - gas and electrics especially the earthing it's the difference between life or death kill two birds with one stone get quotes from electricians for fuse box replacement they will test the earthing if it is just the fuse box i think the quotes you had are way over the top

brian, February 2011