Fuses, Breakers, Amps, Max Load... Crossy!

[Naam]

^ 555

nice memories of the 20 year old port

for the record: the Port was 30 years old when it was bottled and then stored 5-7 years in my home.

but i think we would have had an equal good time with an excellent "young" port

[Forkinhades]

It was that good, it wiped my memory of how old it was, I always bring a bottle over from Blighty every time I come now. Alas it does not last long though.

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[Naam]

another apprentice question for Crossy, Forky and who might have specific know about Thai public grid supply:

-my meter is rated 15/45A,

-the feeder cables to the meter have each a ‎net copper Ø of 9.3mm = 68 mm² = being able to carry a max load that is a multiple of the meters rating,

-what happens to the meter if by accident or deliberately much higher amps then the meter's rating are drawn?

POOF?

[Forkinhades]

Indeed, meltdown with a poof, and fire possibly, because the PEA do not fuse down past the Tx.

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[Crossy]

Exactly Forky, I suspect that the meter is the weak link, any short downstream will likely result in explosive destruction of the meter, a damned expensive "fuse"

[Naam]

Without a diagram we are really going to struggle here trying to work out what's popping the fuses.

Knowing what we now know I would NOT replace with bigger fuses, but 30A MCBs would be OK and easier to reset should they open.

overlooked that advice. thanks Crossy, that's what i will do.

You really should consider lower rated MCBs for your control circuits. (post 98)

back to the past Forky. in the meantime i found out that the 32A porcelain fuses are not for the control circuits. they are working in line with the 45A breakers and act as some sort of "first defence" should an overload of one phase occur. since they are "time delay" (in Germany we call them "lazy") fuses they can obvious take much more than 32A but only for a limited time. the reason why that one and only fuse popped was when i let all aircons run for more than 12 hours to compensate for a pre-announced power cut for the whole next day.

evidence for my "first defence" apprentice assumption (which was later confirmed by a "master") was my experiment to pop in a 10A fuse and switched on all 7 aircons connected to that phase. the fuse lasted between 5 and 6 minutes and (miraculously?) the 45 MCB sensed the pop and tripped. only after resetting the MCB which of course failed to trigger the "SNs" i realised that the porcelain fuse popped.

conclusion: no such thing to replace with lower rated CMBs.

[Forkinhades]

Hhmm, interesting

Did we not agree that the cables feeding the 'lazy fuses' were rather small for 32A?

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[Naam]

Exactly Forky, I suspect that the meter is the weak link, any short downstream will likely result in explosive destruction of the meter, a damned expensive "fuse"

can't happen in ol' Germany. we have these old style screw-in fuses installed by the electricity company before the meter. these fuses are in a box with lead seals which a homeowner is not allowed to open. opening that box and replacing a damaged fuse = huge penalty!

when i told my German master sparky that no such things are installed in Thailand he didn't believe me and wanted to bet any amount that this is impossible. little did he know, but then... he's only a Tchermann with no exposure to jungle electrics

but back to the meter "poof". there must be some safety buffer as far as the meter is concerned. a bridge which is rated 45 tons max load is structurally engineered to take at least a 50% or even higher load.

i can't imagine that the innerts of Thai meters are designed to tolerate 45A but "poof" when 46A are drawn. any idea about that buffer?

my question is a purely academic one Gentlemen. i have no plans whatsoever to draw more amps than the meter is rated.

[Forkinhades]

I would say they could cope with one third more than the rating.

Did your techman advise on your box of tricks? Which you would not let me poke anything into.

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[Naam]

Hhmm, interesting

Did we not agree that the cables feeding the 'lazy fuses' were rather small for 32A?

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that was indeed the case but being an apprentice i can't come up with a reasonable explanation.

[Forkinhades]

Well if everything is working fine, no need to fix anything (>﹏<)

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[Naam]

I would say they could cope with one third more than the rating.

Did your techman advise on your box of tricks? Which you would not let me poke anything into.

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the chap who built it is dead. and whoever took a look into the box is not sure what exactly is going on. that is quite worrying and i dread the event should something go wrong in the trick box and my whole home has no power.

that's why the next planned venture is to install some switch gear which simply bypasses the trick box should something go wrong that can't be fixed in a rather short time. i am thinking of something utmost simple like switching from grid to a generator and that done manually. we have lived several years in the African bush, i.d. even the Mrs is used to move a handle up or down.

[Forkinhades]

....Glass of Port?

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[Naam]

....Glass of Port?

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you mean i had already Port to come up with this idiotic idea?

[Forkinhades]

I will make a point to visit, next time I have a full bottle of port.

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[Naam]

I will make a point to visit, next time I have a full bottle of port.

your visit (in about 2-3 weeks) would be highly appreciated. but i don't like it when guests arrive with bottles.

[JesseFrank]

I will make a point to visit, next time I have a full bottle of port.

your visit (in about 2-3 weeks) would be highly appreciated. but i don't like it when guests arrive with bottles.

Looking at that forehead I would also be wary about another guest arriving with a bottle .