Earth cable sparking

cash99

I have just fitted an earth terminal block in order to bond a new tv aerial amplifier. To fit the block I simply cut into one of the earth cables from the main earthing point (PME) and rejoined it through the earth block. All well and good so far.

However as I rejoined the earth cable on the consumer unit side there was a slight spark. Not the full blown short of mains, more like the spark when you reconnect a car battery. I was able to repeat the spark just to make sure I hadn't imagined it.

The consumer unit in question has a 30mA Rcd covering most of the circuits, and I don't have any other faults.

Can anyone tell me what is causing this?

Thanks in advance

YorkshireBoy

cash99 wrote:

...I simply cut into one of the earth cables from the main earthing point (PME) and rejoined it through the earth block. All well and good so far.

I like the use of the phrase "simply cut into the earth cables". The next time we see it, it will look something like...

Here lies CASH99 - he "simply cut into the earth cables" - RIP

The wire you "simply cut into" would/should have had a label attached at it's termination point(s) stating "SAFETY ELECTRICAL CONNECTION - DO NOT REMOVE".

Playing with main earthing conductors is extremely dangerous on PME systems (in fact on any electrical system). This kind of work should be left to the professionals.

By the way, the technical answer to your question is circulating neutral/earth currents resulting from increased potential difference - it would take much longer to put it into laymans terms. Lets leave it there.

Finally, did you really need "protective earthing" which is sort of what you've done, or was it only "functional earthing" (as in BT systems) that was required?

Take care and STAY SAFE.

YB

cash99

YorkshireBoy wrote:

By the way, the technical answer to your question is circulating neutral/earth currents resulting from increased potential difference - it would take much longer to put it into laymans terms. Lets leave it there.

Yorkshire Boy - So this is normal, and not a fault then?

YorkshireBoy wrote:

I like the use of the phrase "simply cut into the earth cables". The next time we see it, it will look something like...

Here lies CASH99 - he "simply cut into the earth cables" - RIP

Believe me I have a very healthy regard for electrical safety.I have seen the effects of elctrocution first hand when the electricity board came to move my supply. One electrician had to be resuscitated and his mate nearly joined him when he tried to garb hold of him.

YorkshireBoy wrote:

The wire you "simply cut into" would/should have had a label attached at it's termination point(s) stating "SAFETY ELECTRICAL CONNECTION - DO NOT REMOVE".

It didn't but it does now, and the cable has not been removed.

YorkshireBoy wrote:

Finally, did you really need "protective earthing" which is sort of what you've done, or was it only "functional earthing" (as in BT systems) that was required?

I have fitted a loftbox tv aerial amplfier which has a separate earth stud which the intructions say should be earth bonded back to the main electrical earth bonding. I believe this is to do with lightning hitting the tv aerial. Presumably this is correct otherwise the coax cable conected to the amplifier would become live if the aerial is hit by lightning.

Thanks for the reply

Pink.

Just a reminder of the warning at the top of this board:

Warning! Always use a professional for gas maintenance and complex electrical repairs. Being safe is more important than MoneySaving.
10-02-2005 MSE Andrea (Official Administrator)

Pink