UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > General Vintage Technology Discussions

Notices

General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc.

Closed Thread
 
Thread Tools
Old 31st Mar 2017, 7:11 pm   #1
PaulR
Dekatron
 
PaulR's Avatar
 
Join Date: Oct 2003
Location: Southport Lancashire, UK.
Posts: 3,221
Default Hot 13A plug pin

Not really "vintage" and I hope this isn't a daft question, but I have always wondered why only the live pin of a 13A plug gets warm if run near its limit. If the current flows through the neutral as well why doesn't that get equally hot?
__________________
Paul
PaulR is offline  
Old 31st Mar 2017, 7:17 pm   #2
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
Default Re: Hot plug pin

Because the live pin is not solid brass, but split to accept the end cap of the fuse. So it has a smaller cross-sectional area, therefore a higher resistance.
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments.
julie_m is offline  
Old 31st Mar 2017, 7:26 pm   #3
PaulR
Dekatron
 
PaulR's Avatar
 
Join Date: Oct 2003
Location: Southport Lancashire, UK.
Posts: 3,221
Default Re: Hot plug pin

Thanks Julie, I wondered whether it was something to do with the fuse
__________________
Paul
PaulR is offline  
Old 31st Mar 2017, 7:30 pm   #4
teetoon
Heptode
 
Join Date: Dec 2010
Location: Barnstaple, N.Devon, UK.
Posts: 556
Default Re: Hot plug pin

Hi Paul. It's more to do with the fuse than the actual pin. Often there is a screw or a rivet on the top of the pin securing the fuse holder and these can get loose with age. The fuse will also become warm if run close to it's full rating.
I used to run a disco and the lighting supply plugs would need to be checked and the fuse holders cleaned occasionaly to keep them from getting hot at times of full loading.
I've seen plugs on large appliances (3kw fires etc) where the plug has gone brown on the fuse area. Quite often because the screws / fuse holders are not tight enough and then the resulting resistance makes the matter worse.

David.
teetoon is offline  
Old 31st Mar 2017, 10:26 pm   #5
Refugee
Dekatron
 
Refugee's Avatar
 
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
Default Re: Hot plug pin

When I worked in a calibration lab the engineer who worked next to me got a whole day worth of power meters with 1Kw RF dummy loads to check.
By lunch time a burning plastic smell was being traced to a power socket. You could see the shape of the plug in black charcoal on the socket face-plate.
Refugee is online now  
Old 1st Apr 2017, 6:42 pm   #6
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
Default Re: Hot plug pin

In the 1960's my aunt had a red rubber plug from Woolworths on her 3kW electric fire that used to get so hot that the rubber went very soft indeed. On one visit I noticed that the rubber had perished so badly that a piece had come away, exposing the brass top of the fuse-retaining clip, and immediately went and got her a new plug. In the "hot" plug, the fuse cap was located in a groove in the end of the pin and held in place by a fairly rigid clip, rather than between two springy split ends of the pin or two springy fingers attached to the end of the pin.
emeritus is offline  
Old 1st Apr 2017, 10:01 pm   #7
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,527
Default Re: Hot plug pin

I never liked any rubber plugs at 3kW. Nor any cheapo hard plastic ones either. MK ones with binding screw wire connections were good and seemed to run cooler than any other make.
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline  
Old 2nd Apr 2017, 7:55 pm   #8
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,952
Default Re: Hot plug pin

The 13A fuse itself is a "resistor" that heats its end-clips, causing oxidisation and elevated resistance (and so higher losses and more heat) in the plug.

To be Honest, I've never really liked the BS1313 fused-plug and "ring" wiring; separately-fused radial circuits with a 15A fuse at the head-end and BS546 15A unfused plugs/sockets at the end-points make more sense to me: such a circuit can deliver the rated current indefinitely without needing to worry about other loads introducing themselves....
G6Tanuki is online now  
Old 3rd Apr 2017, 10:51 am   #9
Brigham
Octode
 
Join Date: Mar 2006
Location: Co. Durham, UK.
Posts: 1,111
Default Re: Hot plug pin

My thoughts precisely. The fused plug is for convenience, the ring-main for economy.
Brigham is offline  
Old 3rd Apr 2017, 1:41 pm   #10
PaulR
Dekatron
 
PaulR's Avatar
 
Join Date: Oct 2003
Location: Southport Lancashire, UK.
Posts: 3,221
Default Re: Hot 13A plug pin

I suppose that when radial circuits were the norm there were far fewer sockets in the average house. Wouldn't a separate circuit for each socket be rather unwieldy these days?

Having said that, my son has been doing some electrical work at his house and found that the neutral at one end of the upstairs ring was not connected at all at the consumer unit.
__________________
Paul
PaulR is offline  
Old 3rd Apr 2017, 4:26 pm   #11
cmjones01
Nonode
 
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
Default Re: Hot plug pin

Quote:
Originally Posted by Brigham View Post
My thoughts precisely. The fused plug is for convenience, the ring-main for economy.
And, without getting too far off topic, the ring-main is for surge capability, too. I live in a country with 16A radial circuits and it drives me nuts having to add soft-start circuits to anything with a large transformer or even hefty primary-side smoothing capacitors in it. I have to hold my breath each time I switch on my trusty Tek 535A scope, and the security guard at the office is well used to me coming to ask for the key to the electrical panel to reset the circuit breaker to my office. Yes, people say, fit a C-type circuit breaker, but that's not possible in a rented office.

Give me a 32A ring main and fused plugs any day!

Chris
__________________
What's going on in the workshop? http://martin-jones.com/
cmjones01 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 9:02 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.