Quiz

[Octopus]

Just been doing an EICR and as there was no seal I decided to check the rating of the DNO fuse.

The photo below is what I could see!!

Can any one, with any confidence, say whether which rating of fuse it is??

Also would you report the "holder" to the DNO due to the "rust" on it?

Thanks

 

[telectrix]

could tell DNO it's smelling weird and crackling. you can't be sure why, as no way would you pull a DNO fuse.

 

[highspark]

If I can't identify main fuse. Always the case I just note on PIR/EICR...could not identify main fuse as a limitation!

 

[a1guvner]

could tell DNO it's smelling weird and crackling. you can't be sure why, as no way would you pull a DNO fuse.

With you on that one, with a LIM on your certs

 

[Edd]

Nice bit of heat damage!! you gota think thats happened for a reason, (loose conection, bad fitting fuse) if you put it back and tip toe away!! what could the damage be like in the service head its a fault waiting to happen... get the ocupier to phone.. I hate phoning the DNO .....

Oh my guess is a 1361 60A

 

[Darkwood]

Ring dno emergency line tell them it was red hot, smoking and smelling bad so you've switched main board off... they will send someone out on emergency and replace the whole cutout hopefully as the cutout receiving pins would be damaged too, the structure of the copper will have been changed under so much heat and may not be able to do its job due to losses in the sprung metal which wouldn't then be able to maintain a tight strong connection, you can also ask if it would be safer to withdraw cutout fuse now or wait for DNO and see what her advice is?

 

[Octopus]

Ring dno emergency line tell them it was red hot, smoking and smelling bad so you've switched main board off... they will send someone out on emergency and replace the whole cutout hopefully as the cutout receiving pins would be damaged too, the structure of the copper will have been changed under so much heat and may not be able to do its job due to losses in the sprung metal which wouldn't then be able to maintain a tight strong connection, you can also ask if it would be safer to withdraw cutout fuse now or wait for DNO and see what her advice is?

Might do that after I've changed the CU on Monday!!

 

[Darkwood]

Just been doing an EICR and as there was no seal I decided to check the rating of the DNO fuse.

The photo below is what I could see!!

Can any one, with any confidence, say whether which rating of fuse it is??

Also would you report the "holder" to the DNO due to the "rust" on it?

Thanks

View attachment 10215

There isnt any rust i can see, what your seeing hear is the white/green powder is because the copper has been glowing red hot and is a vapourised copper coating as it reacted with the air ... what still amazes me as i seen this a few times is that the fuse wire inside reacts and fuses to temperature created by excessive current flow, yet the clasp got glowing red on the pins but still didnt conduct enough heat into the fuse wire to melt.

 

[ipf]

Rust? Has it been in contact with water?

 

[telectrix]

you only get rust on iron and steel. ferrous oxide, Fe03, if i remember correctly. from copper you get copper oxide, and sulphates.

 

[ipf]

Beat me to it darkwood.

 

[ipf]

Nice one Tel.

 

[Edd]

copper oxide is a black layer that can be seen near the end of the fuse holder, the green is a mixture of chloride and carbonate. As the black copper oxide is pressent then it could be classed as copper rust! but rust normally means iron involved. Oxidation is another name for it.

side note for people intrested,,, People often make the mistake that oxygen is needed in a oxidation chemical reaction, but its not. A chemical reaction where electrons are taken is a redox (reduction/ oxydation)(ionic bonding) reaction.. sodium and chlorine is a good example of a redox reaction making sodium chloride (salt). no oxygen involved but an oxidation took place..
(one of my hobby's is chemistry and fireworks) not done it in ages so am a little rusty on it.. sorry if i bored everyone

 

[telectrix]

see your point. and well remember experimenting with weedkiller and sugar. now that's what i call fireworks.

 

[RogertheBodger]

Go on, get technical, and here's me thinking the Sulphates was in the middle east somewhere