I have an underground cable controlling a water pump which supplies my house
, The cable is armoured. Is it necessary to earth the metal armour
protection?
Blair

On Tue, 24 Jan 2006 05:45:30 -0000 someone who may be "Blair"
wrote this:-

I have an underground cable controlling a water pump which supplies my house
, The cable is armoured. Is it necessary to earth the metal armour
protection?

Yes.

Whether you make such a connection at both ends depends on how you
are earthing the pump and any building it is in. There have been
several threads on this recently to do with garages.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"Blair" wrote in message
...
I have an underground cable controlling a water pump which supplies my
house
, The cable is armoured. Is it necessary to earth the metal armour
protection?

Definitely. There should be a brass tag for that purpose in the cable gland
set.

Colin Bignell

"nightjar .uk.com" nightjar@insert my surname here wrote in message
...

"Blair" wrote in message
...
I have an underground cable controlling a water pump which supplies my
house
, The cable is armoured. Is it necessary to earth the metal armour
protection?

Definitely. There should be a brass tag for that purpose in the cable
gland
set.

Colin Bignell

Thanks for your reply.
I should have said that I have a metal junction box where the cable armour
is earthed as you say but I am proposing to change this to a plastic
junction box, and there will be no earth available.
Can I safely do this?
Blair

On Wed, 25 Jan 2006 05:06:12 -0000 someone who may be "Blair"
wrote this:-

I should have said that I have a metal junction box where the cable armour
is earthed as you say but I am proposing to change this to a plastic
junction box, and there will be no earth available.

Why will there suddenly be no earth available because you change the
box?

Can I safely do this?

Assuming the junction box is at the other end of the cable to the
pump. No.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
...
On Wed, 25 Jan 2006 05:06:12 -0000 someone who may be "Blair"
wrote this:-

I should have said that I have a metal junction box where the cable
armour
is earthed as you say but I am proposing to change this to a plastic
junction box, and there will be no earth available.

Why will there suddenly be no earth available because you change the
box?

Can I safely do this?

Assuming the junction box is at the other end of the cable to the
pump. No.


--
David Hansen, Edinburgh
The metal junction box is at the pump end of the cable and the metal
protection is connected to the gland which is used for the cable. If I
replace the metal box with a plastic one this gland will not be in contact
with any metal and therefore not earthed..
Of course there is an earth wire within the cable. Are you suggesting that
the metal protection should be connected to this earth?
Blair

On Thu, 26 Jan 2006 13:21:50 -0000 someone who may be "Blair"
wrote this:-

The metal junction box is at the pump end of the cable and the metal
protection

I assume you mean the armour.

is connected to the gland which is used for the cable. If I
replace the metal box with a plastic one this gland will not be in contact
with any metal

The gland will not be in contact with any metalwork forming the box
(as the box is now plastic), though it will still be in contact with
the armour.

and therefore not earthed..

That does not follow at all, assuming that the armour is earthed at
the origin of the cable.

Is there an earth rod at the pump end? If there is then all sorts of
other considerations apply.

Is the pump Class I or Class II?

Of course there is an earth wire within the cable. Are you suggesting that
the metal protection should be connected to this earth?

The armour should be earthed. How this is done depends on a host of
things. What sort of earthing system is in use?

Why do you want to change the box? Do you think you are skilled
enough to do so?


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54