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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Earthing query
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 |
#2
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Earthing query
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 |
#3
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Earthing query
"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 |
#4
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Earthing query
"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 |
#5
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Earthing query
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 |
#6
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Earthing query
"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 |
#7
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Earthing query
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 |
#8
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Earthing query
"David Hansen" wrote in message ... 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 From: "David Hansen" Subject: Earthing query Date: 26 January 2006 14:21 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 From: "David Hansen" Subject: Earthing query Date: 26 January 2006 14:21 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 have a junction box in the garage which is fed from a spur in the garage ring main and is protected by an RCD. The supply is a three core cable I have used a correctly sized armoured gland with a brass earth tag which is connected to the earth from the supply cable At the other end next to the pump a similar brass tag is used which earths the armour to the box.There is no earth rod at the pump So I believe the system is at present earthed correctly. If I did use a plastic box I assume that the brass earth tag should be connected to the supply earth wire for full protection Incidentally I installed the whole system about 12 years ago which consists of a pump previously submersible but now surface mounted. pressures vessel and a pressure switch.Water is pumped up about 50 feet from source. I probably should leave it alone and forget the plastic box? Blair |
#9
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Earthing query
On Fri, 27 Jan 2006 14:57:54 -0000 someone who may be "Blair"
wrote this:- I have a junction box in the garage which is fed from a spur in the garage ring main and is protected by an RCD. The supply is a three core cable I have used a correctly sized armoured gland with a brass earth tag which is connected to the earth from the supply cable This junction box is presumably plastic? If not then provided the metal of the box is earthed in some way everything sounds like it is in order. At the other end next to the pump a similar brass tag is used which earths the armour to the box.There is no earth rod at the pump If you replace this with a plastic box then, assuming the pump is Class I equipment, you need a similar arrangement to that which you described inside the garage, with the earth tag connected to the earth conductor in the lead to the pump. So I believe the system is at present earthed correctly. It sounds like it. If I did use a plastic box At which end? I assume that the brass earth tag should be connected to the supply earth wire for full protection If you are talking about the one in the garage then yes. If you are talking about the one by the pump then I can only imagine you are using one of the cores as an earth, in addition to the armour. It is good practice to connect both together at this end as well. I probably should leave it alone and forget the plastic box? Out of interest, why do you want to replace the metal box? -- 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 |
#10
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Earthing query
"David Hansen" wrote in message ... On Fri, 27 Jan 2006 14:57:54 -0000 someone who may be "Blair" wrote this:- I have a junction box in the garage which is fed from a spur in the garage ring main and is protected by an RCD. The supply is a three core cable I have used a correctly sized armoured gland with a brass earth tag which is connected to the earth from the supply cable This junction box is presumably plastic? If not then provided the metal of the box is earthed in some way everything sounds like it is in order. No this junction box is metal At the other end next to the pump a similar brass tag is used which earths the armour to the box.There is no earth rod at the pump If you replace this with a plastic box then, assuming the pump is Class I equipment, you need a similar arrangement to that which you described inside the garage, with the earth tag connected to the earth conductor in the lead to the pump. So I believe the system is at present earthed correctly. It sounds like it. If I did use a plastic box At which end? At the pump end I assume that the brass earth tag should be connected to the supply earth wire for full protection If you are talking about the one in the garage then yes. If you are talking about the one by the pump then I can only imagine you are using one of the cores as an earth, in addition to the armour. It is good practice to connect both together at this end as well. I probably should leave it alone and forget the plastic box? Out of interest, why do you want to replace the metal box? I am struggling to give a sensible answer. In the past I had the pressure switch adjacent to the pump in a wooden box with insulation for frost protection. Mice got in and chewed the plastic insulation and generally caused a mess including the junction box. Since installing the new pump I have built a brick housing to make it mouse proof and I wanted to tidy up the wiring and fit a new junction box. Why plastic.? probably because it looks better!! Not a good reason! Blair |
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