Please help - do we need earth bonding?

jap200

My father-in law, who is a retired (and a bit 'rusty') electrician, has told us that we should get our new bathroom and en-suite earth-bonded. We have just had the en-suite built from scratch, but the bathroom suite will be just a replacement of the existing one.

I asked the builder (who is not a certified electrician) about this and he said that we do not need earth bonding as we have a new consumer unit with an RCD (which I think is a kind of circuit breaker). My father-in-law disagrees.

Please can anybody enlighten me as to what is the correct answer as I really don't know anything about it, but we obviously need to do the right thing.

If we do need it, we need to get it done before the pipes are all boxed in, which will be later this week.

plumb1_2

Bonding still req

http://www.diydoctor.org.uk/projects/bondingbathroom.htm

IJJoseph

Echo plumb1. Latest edition of the wiring regs and (Part P?) stipulate all copper/metal pipes have to be bonded.

ohreally

Listen to your father-in-law...he knows best (get him to do the bonding,it won't take him long).

jap200

ohreally wrote:

Listen to your father-in-law...he knows best (get him to do the bonding,it won't take him long).

The consensus seems to be that we need the earth-bonding. As far as the father-in-law is concerned he has been a fantastic help with our electrics in the past, but his health is not great these days, so we may have to get the builders to do it.

Thanks to everyone for their help on this one though.

ohreally

jap200, do the bonding yourself then. It's easy and your father-in-law can give you advice on how to do it if your unsure, you need earth bonding clamps, 6mm earth cable, terminals and a crimping tool and Bob's your aunty

IJJoseph

Don't even need the crimping tool anymore....just a spanner and a screwdriver

cabbageboy

YES YES YES - You STILL need earth bonding!!!

The RCD device will only protect you if there IS an earth bonding - otherwise it's useless!! That's the whole point of an RCD - it relies on an Earth connection to detect that anything is wrong!

I agree with the others - do it yourself with your father-in-law's advice - it's got to be better than those builders who obviously know absolutely nothing, and probably won't do it right if you asked them!

grumbler

cabbageboy wrote:

The RCD device will only protect you if there IS an earth bonding - otherwise it's useless!! That's the whole point of an RCD - it relies on an Earth connection to detect that anything is wrong!

I think this is not correct.

http://en.wikipedia.org/wiki/Residual_current_device

....a RCD will trip if current leaks anywhere, not just to ground. One might more properly call the device a Balance Fault Interrupter...

I don't argue wheather earth-bonding is needed or not though ...

Plasticman

cabbageboy wrote:

The RCD device will only protect you if there IS an earth bonding - otherwise it's useless!! That's the whole point of an RCD - it relies on an Earth connection to detect that anything is wrong!

Not the case with an RCD. The old earth leakage trips (ELCB's) used to work this way but RCD's look for leakage anywhere. From (slightly dodgy) memory, RCD's measure the difference in current between live & neutral which, if there is no leakage, should be the same. If you touch the live wire some of the current will pass through your body and therefore the live & neutral will not balance & the trip will cut out.

Hunnymonster

Plasticman wrote:

From (slightly dodgy) memory, RCD's measure the difference in current between live & neutral which, if there is no leakage, should be the same. If you touch the live wire some of the current will pass through your body and therefore the live & neutral will not balance & the trip will cut out.

Yup - although as I understand it, it works by having 2 coils counterwound so that when the current is the same in live & neutral the field is zero, when the field is unbalanced by a current loss (or gain) then it pushes a plunger to break the circuit. Not measured as such....

But back to the plot - regardless of the sensitivity of the breaker, or what technology it uses..... there's no substitute for doing the job properly in the first place - earth bonding costs next to nothing to do compared to the alternative - a funeral (sounds dramatic, but it's a real possibility - although it should be very improbable). Get it bonded!