Vary stupid electrical questiom (1 Viewer)

Feb 22, 2016
3,608
10,667
York
Funster No
41,744
MH
Bailey 620 Approach
Exp
Since 2015
Oh dear!:eek: The PC polis will be along shortly!
Suggest you change it to "What's crispy and hangs from the ceiling? An amateur electrician. ;):giggle:


Edit .......... See told you! nicholsong agrees!
Well, if anyone is so twisted as to see any racial aspect to the old, poor taste joke (insofar as electricians are concerned) they're welcome to report me. I await the 5:30a.m.knock on the door.

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chenderson1965

chenderson1965

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Aug 3, 2019
327
274
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62,953
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N+B Arto 79R A Class
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10 years with hires, Newbie owner
I don’t know what the flash was. It might have been a cheap socket or possibly a bit of moisture on the plug. It’s now plugged into the same socket and working perfectly so seems to be okay. I’ll keep an eye on both the plug and the socket to see if there’s any other way behaviour from it.

Thanks all for your advice. Offer a happy holiday now!

Chris
 
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chenderson1965

chenderson1965

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Aug 3, 2019
327
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Ha! Phone dictation error. Meant 'Off for a'. Think wife would object to guests, maybe next time!

Hartington in Derbyshire.

Chris
 
Sep 9, 2019
848
1,893
Runcorn
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63,956
MH
Autotrail Apache 632
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With my sparking head on I shall venture to offer an explanation, Sherlock Holmes styley, for the “Case of the missing fuse” If you look carefully at the OP’s pic of the fuse you will see that the contacts are wider than they should be to retain the fuse and give a solid electrically sound contact, the fuse has been loose in the contacts and as it’s been pushed into the socket it’s “flashed” as it re-made electrical contact. It’s likely that the fuse will still be ok. The reason it was loose in the first place is likely to be twofold, 1, the contacts are made of brass and as such are not very springy and are inclined to loosen with replacement of fuses, 2, if the fuse has been running near it’s 13amp capacity it is likely to get very hot and transfer the heat to the brass contacts which will in turn loosen with the heat. A BS1361 type fuse (the fuse in question) has a “fusing factor” of double it’s rating, so it needs to see 26+amps before it will “blow” and when I say “blow” I mean it literally blows up, the fuse material melts and goes from a solid, metallic state, through a liquid state, to a gaseous state in milliseconds, the difference in volume occupied by a solid piece of fuse and a gaseous, “blown” fuse is roughly 1000 times, hence the bang and flash characteristics you invariably witness at electrical problem sites.

On a positive note, and now with my engineer’s head on, the OP can effect a repair reasonably easily by pushing the contacts within the plug closer together, thus ensuring a firm grip on a replacement fuse. I still strongly recommend the switching on process I outlined in an earlier post......

Cheers!

Sherlock....Er.....Russ!
 
Feb 21, 2016
4,913
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41,726
MH
C class
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Since 2017
Hi RustyRuss . Just want to say how refreshing it is to read an explanation on electrics that even I can understand! Most information on the subject seems to be aimed at those who already have a phd in it.
So many of the problems on motorhomes seem to be leccie related it must be good to know what you’re doing! Thanks.:giggle:(y)

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chenderson1965

chenderson1965

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Aug 3, 2019
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Hi RustyRuss . Just want to say how refreshing it is to read an explanation on electrics that even I can understand! Most information on the subject seems to be aimed at those who already have a phd in it.
So many of the problems on motorhomes seem to be leccie related it must be good to know what you’re doing! Thanks.:giggle:(y)
Agreed. It’s so refreshing to get some advice from firstly someone who Deeply understands the subject and secondly someone who is able to communicate it clearly and simply.

Thanks again.

Chris
 
Dec 20, 2018
707
870
Funster No
57,651
MH
C Class
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Since 2004
Russ,

Would you not have expected something like that to have tripped either a breaker or RCD on the house consumer unit? Should it be a concern if it didn't?

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Jun 29, 2015
3,462
57,123
Southampton
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36,999
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caravan (for now)
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on and off since 1984
Russ,

Would you not have expected something like that to have tripped either a breaker or RCD on the house consumer unit? Should it be a concern if it didn't?
If it was a short between line and neutral it would have no affect on the RCD, and if the short blew the 13 amp fuse fast enough, it may not have taken out the 32 amp breaker
 
May 7, 2016
7,230
11,697
West Sussex
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42,951
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Carthago Compactline
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Russ,

Would you not have expected something like that to have tripped either a breaker or RCD on the house consumer unit? Should it be a concern if it didn't?

The lowest amperage fuse/breaker in the whole circuit was probably the 13Amp one in the plug, so it would be the first to go. I believe an RCD monitors the power in the positive and negative connections and if they go out of balance the device is tripped. The breakers and fuses protect the wiring and devices but the RCD protects the user. In a motorhome the RCDs needs to be 2 pole devices which switch off both positive and negative connections because outside the UK polarity is not seen as important so either one can be live. Even more important with an inverter because some of them use both wires out of phase to achieve 230V, seen as safer because each wire is running at a lower voltage.

I expect to be corrected by one of the qualified electricians on here if my understanding is misguided.
 
Sep 9, 2019
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1,893
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MH
Autotrail Apache 632
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You’re on the money Pausim! (y)

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