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Crimps, heat shrink and phase/earth shorts - wtf?!
Just finished a day of rewiring the lights circuit in the kitchen - not
finished the whole lot yet, but the main lights are done. Test it. Short between phase and earth. Arghhh. Track it down to a section of cable with a crimp in. Hmmm. Cut out crimp, short disappears. Remove the heatshrink, inspect cable. Can't find anything wrong. Pull through some slack, remake crimp. No short. Get the hairdryer out, and shrink the heat-shrink around the sheath. Short reappears. It's not a dead short - it's 43ohms. I'm inclined to leave it overnight and see what I measure in the morning.... Any ideas what's going on?! Ben |
Crimps, heat shrink and phase/earth shorts - wtf?!
On Sun, 15 Apr 2007 19:45:43 +0100, Ben Blaukopf
mused: Just finished a day of rewiring the lights circuit in the kitchen - not finished the whole lot yet, but the main lights are done. Test it. Short between phase and earth. Arghhh. Track it down to a section of cable with a crimp in. Hmmm. Cut out crimp, short disappears. Remove the heatshrink, inspect cable. Can't find anything wrong. Pull through some slack, remake crimp. No short. Get the hairdryer out, and shrink the heat-shrink around the sheath. Short reappears. It's not a dead short - it's 43ohms. I'm inclined to leave it overnight and see what I measure in the morning.... Any ideas what's going on?! Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. I always insulate the crimps individually before applying an overal insulation to prevent this. -- Regards, Stuart. |
Crimps, heat shrink and phase/earth shorts - wtf?!
In message , Ben Blaukopf
writes It's not a dead short - it's 43ohms. I'm inclined to leave it overnight and see what I measure in the morning.... Any ideas what's going on?! You're definitely not heating the cable up to the point where wire melts within the jacketed area? -- Clive Mitchell http://www.bigclive.com |
Crimps, heat shrink and phase/earth shorts - wtf?!
Clive Mitchell wrote:
In message , Ben Blaukopf writes It's not a dead short - it's 43ohms. I'm inclined to leave it overnight and see what I measure in the morning.... Any ideas what's going on?! You're definitely not heating the cable up to the point where wire melts within the jacketed area? Nope. I completely disassembled the first one, and there was no sign of any damage whatsoever. Ben |
Crimps, heat shrink and phase/earth shorts - wtf?!
Lurch wrote:
On Sun, 15 Apr 2007 19:45:43 +0100, Ben Blaukopf mused: Just finished a day of rewiring the lights circuit in the kitchen - not finished the whole lot yet, but the main lights are done. Test it. Short between phase and earth. Arghhh. Track it down to a section of cable with a crimp in. Hmmm. Cut out crimp, short disappears. Remove the heatshrink, inspect cable. Can't find anything wrong. Pull through some slack, remake crimp. No short. Get the hairdryer out, and shrink the heat-shrink around the sheath. Short reappears. It's not a dead short - it's 43ohms. I'm inclined to leave it overnight and see what I measure in the morning.... Any ideas what's going on?! Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. I always insulate the crimps individually before applying an overal insulation to prevent this. That's the one. I'll remake it with individual insulation. I guess heating it up is just tipping it over the edge. Ben |
Crimps, heat shrink and phase/earth shorts - wtf?!
On Sun, 15 Apr 2007 20:15:03 +0100, Lurch
mused: Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. Also heating it up won't help the minimal amounts of insulation left. -- Regards, Stuart. |
Crimps, heat shrink and phase/earth shorts - wtf?!
It's not a dead short - it's 43ohms.
Fit a heatsink and let it dissipate 1.5KW |
Crimps, heat shrink and phase/earth shorts - wtf?!
More seriously, maybe the real partial-short is nearby and breaking/
remaking the join just disturbed it a bit? |
Crimps, heat shrink and phase/earth shorts - wtf?!
|
Crimps, heat shrink and phase/earth shorts - wtf?!
|
Crimps, heat shrink and phase/earth shorts - wtf?!
In article , Lurch
writes On Sun, 15 Apr 2007 20:15:03 +0100, Lurch mused: Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. Also heating it up won't help the minimal amounts of insulation left. Where's part Pee come into this?... -- Tony Sayer |
Crimps, heat shrink and phase/earth shorts - wtf?!
On Sun, 15 Apr 2007 21:19:37 +0100, tony sayer
mused: In article , Lurch writes On Sun, 15 Apr 2007 20:15:03 +0100, Lurch mused: Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. Also heating it up won't help the minimal amounts of insulation left. Where's part Pee come into this?... Dunno. Why should part p be an issue? -- Regards, Stuart. |
Crimps, heat shrink and phase/earth shorts - wtf?!
In article , Lurch
writes On Sun, 15 Apr 2007 21:19:37 +0100, tony sayer mused: In article , Lurch writes On Sun, 15 Apr 2007 20:15:03 +0100, Lurch mused: Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. Also heating it up won't help the minimal amounts of insulation left. Where's part Pee come into this?... Dunno. Why should part p be an issue? Electrix in a Kitchen?.... -- Tony Sayer |
Crimps, heat shrink and phase/earth shorts - wtf?!
On Sun, 15 Apr 2007 22:48:06 +0100, tony sayer
mused: In article , Lurch writes On Sun, 15 Apr 2007 21:19:37 +0100, tony sayer mused: In article , Lurch writes On Sun, 15 Apr 2007 20:15:03 +0100, Lurch mused: Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. Also heating it up won't help the minimal amounts of insulation left. Where's part Pee come into this?... Dunno. Why should part p be an issue? Electrix in a Kitchen?.... Who said the crimps were in the kitchen? -- Regards, Stuart. |
Crimps, heat shrink and phase/earth shorts - wtf?!
Lurch wrote:
On Sun, 15 Apr 2007 22:48:06 +0100, tony sayer mused: In article , Lurch writes On Sun, 15 Apr 2007 21:19:37 +0100, tony sayer mused: In article , Lurch writes On Sun, 15 Apr 2007 20:15:03 +0100, Lurch mused: Would this be 3 crimps on a twin and earth all encapsulated in one piece of heat shrink? If so, when you crimp the crimp there's not much left of the insulation on it as you've just flattened it. Also heating it up won't help the minimal amounts of insulation left. Where's part Pee come into this?... Dunno. Why should part p be an issue? Electrix in a Kitchen?.... Who said the crimps were in the kitchen? Well I did say I was rewiring the kitchen lights. Tony, I have only one thing to say. SNB. Ben |
Crimps, heat shrink and phase/earth shorts - wtf?!
On Sun, 15 Apr 2007 23:17:04 +0100, Ben Blaukopf
mused: Where's part Pee come into this?... Dunno. Why should part p be an issue? Electrix in a Kitchen?.... Who said the crimps were in the kitchen? Well I did say I was rewiring the kitchen lights. I know, which is why I doubted that the crimps would actually be in the kitchen, but who cares where they are anyway, as long as they connnected properly. -- Regards, Stuart. |
Crimps, heat shrink and phase/earth shorts - wtf?!
In message , tony sayer
writes Also heating it up won't help the minimal amounts of insulation left. Where's part Pee come into this?... Page 974 paragraph 5. "Only persons authorised by the government may hold an operational heat gun in the vicinity of a pudding joint, and only for as long as it takes to shrink the sleeve without melting all the rest of the plastic" -- Clive Mitchell http://www.bigclive.com |
Crimps, heat shrink and phase/earth shorts - wtf?!
Ben Blaukopf wrote:
That's the one. I'll remake it with individual insulation. I guess heating it up is just tipping it over the edge. What brand of crimps are you using? Must admit to never having seen this happen before. I take it you are running the wires insulation into the edge of the crimp so there is no visible ring of copper at the junction? The other thing to do is to stagger the crimps (i.e. each wire a different length) so that they do not overlap. That also gives a neater join with less bulk. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Crimps, heat shrink and phase/earth shorts - wtf?!
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Crimps, heat shrink and phase/earth shorts - wtf?!
On Mon, 16 Apr 2007 13:09:46 +0100, Ben Blaukopf
mused: It's a cam.misc ref; you replied to my original post about Part P and Cambridge BCOs on cam.misc. What I meant was "Do I have to prefix every post I make with 'This work has been notified to the BCO'" Since you ask, it alters a kitchen circuit, so yes it does come under it. You sure about that? -- Regards, Stuart. |
Crimps, heat shrink and phase/earth shorts - wtf?!
Lurch wrote:
On Mon, 16 Apr 2007 13:09:46 +0100, Ben Blaukopf mused: It's a cam.misc ref; you replied to my original post about Part P and Cambridge BCOs on cam.misc. What I meant was "Do I have to prefix every post I make with 'This work has been notified to the BCO'" Since you ask, it alters a kitchen circuit, so yes it does come under it. You sure about that? Not 100%, but the sockets I'm putting in are definitely in the kitchen, so it's pretty academic. |
Crimps, heat shrink and phase/earth shorts - wtf?!
John Rumm wrote:
Ben Blaukopf wrote: That's the one. I'll remake it with individual insulation. I guess heating it up is just tipping it over the edge. What brand of crimps are you using? Must admit to never having seen this happen before. Screwfix. They might have a label on, but I'm upstairs with whisky and can't be bothered going down! I take it you are running the wires insulation into the edge of the crimp so there is no visible ring of copper at the junction? yes The other thing to do is to stagger the crimps (i.e. each wire a different length) so that they do not overlap. That also gives a neater join with less bulk. They are staggered. There is a small bit of overlap though. Ben |
Crimps, heat shrink and phase/earth shorts - wtf?!
Ben Blaukopf wrote:
Screwfix. They might have a label on, but I'm upstairs with whisky and can't be bothered going down! Not tried them, so can't comment... Usually get mine from CPC. I take it you are running the wires insulation into the edge of the crimp so there is no visible ring of copper at the junction? yes The other thing to do is to stagger the crimps (i.e. each wire a different length) so that they do not overlap. That also gives a neater join with less bulk. They are staggered. There is a small bit of overlap though. Sounds like losing the overlap would help. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Crimps, heat shrink and phase/earth shorts - wtf?!
Ben Blaukopf wrote:
Just finished a day of rewiring the lights circuit in the kitchen - not finished the whole lot yet, but the main lights are done. Finally got round to another look at this, and it took me two minutes before I realised... Totally my fault. Complete and utter loss of brain. I'm an idiot. I've been doing lots of work on the kitchen ring main. Which is RCD protected. The lights circuit obviously isn't, I wasn't testing it at the CU, I was just doing a quick sanity check before energising. So I carefully measured the resistance of a lightbulb and the path thence back to the earth-neutral bond in the cut-out. And yes, I can only assume I was measuring it with the switch turned on, because I was testing live, not switched live. So while my wiring was fine, I'm currently doubting my competence to wield a screwdriver.... Test it. Short between phase and earth. Arghhh. Track it down to a section of cable with a crimp in. Hmmm. Cut out crimp, short disappears. Remove the heatshrink, inspect cable. Can't find anything wrong. Pull through some slack, remake crimp. No short. Get the hairdryer out, Clearly the "no short" bit was me not testing well enough. |
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