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Re: OT: house fires - electrical fault


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UK mains distribution is by an armoured cable which effectively takes the  
form of co-ax. Live and neutral enter the property as one and the same,  
there are often earth staps added to any copper plumbing just to make sure.

Shorting live to either E or N will blow the plugtop fuse and trip the ELCB.  
The problem with cables hidden under carpet is the insulation gets crushed  
when people keep walking on it. Getting a proper short is getting lucky, all  
the dust and crap that falls through the carpet weave accumulates around  
hidden cables and provides the possibility of tracking/arcing between  
conductors with damaged insulation.  


Re: OT: house fires - electrical fault
Ian Field wrote:
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** But that was not the case in 1947 - which is the context here.  

  Rest of your dopey post snipped cos you changed the context.  



.....  Phil  

Re: OT: house fires - electrical fault


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Back then every town had its own power company and no such thing as  
standardisation.

Half the country had DC mains.

Its amazing that those old ways didn't drive us all back into caves.  


Re: OT: house fires - electrical fault
Adrian Jansen wrote:
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In Aus power circuits are 2.5sq mm which is in the main 20 amps so lots  
of circuits have 20 amp breakers supplying numerous outlets
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Re: OT: house fires - electrical fault
Adrian Jansen wrote:
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** The 10A rating of domestic outlets is not a *maximum* but merely a safety rating that equates to a modest temp rise in the conductors. Same goes for 10A rated cables.  

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** A short on a domestic AC outlet supply generates upwards of 200amps.

   Fuses blow and breakers trip instantly.  

  
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** Not really.  

    
....   Phil  

Re: OT: house fires - electrical fault
On 09/03/2016 11:57, Phil Allison wrote:
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The Australian plugs do sometimes run very hot when used at 10A, and I  
have seen them where the plastic around the pins has melted. Perhaps
those were not in ideal condition before they were last used (pins may  
have been tarnished, etc.). I regard the 10A rating as being quite  
"optimistic" for unattended use, and I am even more dubious about the  
similar versions rated at 15A.

I have also seen BS1363 plugs that have slightly discoloured after  
prolonged use at 13A, though the rewireable ones are usually made from  
thermoset materials so they don't tend to melt.




Re: OT: house fires - electrical fault
Chris Jones wrote:
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** A 10amp Aussie plug and socket in average condition will operate happily at 30amps. The to contact contact resistance is in the order of 100 micro-ohms so self heating from that cause is negligible.  

I just tested a 20 year old pair ( Clipsal 415 outlet and 463 plug) to get the above result.

If for some reason a plug and socket is running hot at 10 amps, it definitely needs replacing. The most likely reason is loose or corroded wires in the back of the outlet. Moisture is major contributor to this.  

Since there can be many 10amp outlets on a single circuit, the main risk factor is with the cable in the wall and that is well protected by the usual fuses and breakers.  

My experience with high current AC supply connectors is that ones that run very hot fail by going open circuit, rather than catching fire.


....  Phil  



Re: OT: house fires - electrical fault
Phil Allison wrote:
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We also have a problem with unaproved imports with thinner pins(blades)  
on leads, chargers,power supplies etc.

Re: OT: house fires - electrical fault
On 09/03/2016 16:31, Phil Allison wrote:
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I don't doubt that. Nevertheless from time to time I do see them melted.  
Specifically, it is usually the sort that looks like Clipsal 439 or HPM  
100L. The test-and-tag bloke found one on a hotplate at work last year,  
where the melted plastic had flowed away from around one pin. The pins  
don't seem to fall out, but I don't know if that is because people let  
it cool down before unplugging. The fan heater I had in my youth had a  
moulded-on plug that got very hot, to the point where you wouldn't want  
to touch the pins just after unplugging it, but that one never melted.


Re: OT: house fires - electrical fault


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Don't you lot have fuses in the plugs?!!!  


Re: OT: house fires - electrical fault
Ian Field wrote:
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Don't need them.
Doubt we have worse accident stats.

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