Check your wiring people!

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Sheldoncooper

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I have some of my scarlaris enclosures at 70 to 80% humidity and have never had a problem the heat from the fixture should keep the area that close relatively dry
 

Bluetongue1

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@Smittiferous. You have confirmed that it was in storage and that, I believe, is when the problem would have occurred. Could a wife, partner, your children, visiting neighbours kids, maybe nieces or nephews etc had any possible access? A spilt soft drink not mopped up would have been sufficient to do the damage. Ignoring everything else, the question I would ask you is how else could the steel (iron) on the base of the batten go so rusty without being exposed to significant moisture for a length of time? It wasn’t even exposed directly to the atmosphere...
 

Smittiferous

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@Smittiferous. You have confirmed that it was in storage and that, I believe, is when the problem would have occurred. Could a wife, partner, your children, visiting neighbours kids, maybe nieces or nephews etc had any possible access? A spilt soft drink not mopped up would have been sufficient to do the damage. Ignoring everything else, the question I would ask you is how else could the steel (iron) on the base of the batten go so rusty without being exposed to significant moisture for a length of time? It wasn’t even exposed directly to the atmosphere...

I kept the enclosure locked over that period of dis-use, and it has timber swinging doors as well which I had closed, to prevent my curious kids from being too curious. Likelihood of soft drink being spilled inside is slim to none, really. Not to mention even if it were possible, the enclosure is stored upright, and unless I'm misinterpreting what you're suggesting, the enclosure has always sat upright, with the wiring and sockets on the ceiling, to get soft drink spilled on the sockets would require it squirted or thrown upwards.

Along the line of thought of exposure to salts...

Would sealants, varnishes, lacquers used on the timber contain such salts?
 
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Bluetongue1

APS Veteran
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OK. I was hoping avoid getting too technical, but I do suspect there is also another concurrent problem. The shiny and not quite smooth finish on the iron alloy at the base of one of the bulb holder is not what I would expect from an Australian Standards product. It makes me wonder how much aluminium has been alloyed with the iron. A,luminium is a more reactive metal than copper and its expansion and contraction is significantly greater. It also forms a non-conductive oxidised outer coating, which copper does not. If there is significant aluminium in the iron and aluminium screwshave also been used in the connectors as a result, then you can get electrolytic transfer of aluminum metal that coats the copper (i.e. galvanising). Due to the non-conductive nature of the oxidative outer layer that forms on the aluminium, this brings about an increase in resistance and an increase in heat production. There is also the loosing effect that would occur with aluminium screws contacting the copper wiring - due to continual differential rates of expansion and contraction between the two metals as they heat up and cool down with on/off use. This loosening will also increase the resistance and therefore the heat production. The foregoing is pure speculation but supported by what I can see.
The other potential issue is the actual nature of the wire used. Assuming it is pure copper, it still needs to be of a certain cross-sectional area fo be used safely with the voltage and current invoved. As the degradation of the sheathing around the wires appears to be localised in the vicinity of the connections, I doubt this a significant contributing factor.

How do you account for degree of rust on the bottom of one of the bulb holders if there was no significant moisture?
 

Smittiferous

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[MENTION=41842]Bluetongue1[/MENTION] Simply, I can't account for rust at all. Some of the bulb holders also had a bead of silicone smeared around the base, "sealing" them to the timber blocks they were mounted on, would that not in theory add an additional barrier against direct contact with moisture? You can still see the remnants of it in the image.

I'll take another couple of decent close-ups when I get home from work of that socket, and post them up.
 

Bluetongue1

APS Veteran
APS Veteran
I'll take another couple of decent close-ups when I get home from work of that socket, and post them up.
Don’t worry about that at this stage. Was not well the last few days but am feeling better and thinking more clearly today. I’m beginning to wonder if the corrosion wasn’t secondary to real problem. Can explain later.

I should not have dismissed the mixing of aluminium and copper wiring so quickly. Ion transfer is limited to direct contact i.e. the junction of the wires. However, heating from thinning of the wiring would be readily conducted along the metals, hence the length of heat affected sheath.

Cut a notch in the sheath and then scrape the wire to expose the fresh metal. are all wires coppery or are there some silver coloured?
 

moosenoose

Legendary
I made my enclosures using MDF. Which makes it near impossible to light up. The switchboard will throw a RCD before anything really fun happens...I hope lol
 

Smittiferous

Well-Known Member
[MENTION=41842]Bluetongue1[/MENTION] So I checked the condition of the copper core on several places. Where the flex was in reasonable condition (eg not stiff or discoloured) the copper was a typical shiny copper colour, as one would expect. Even after scraping the surface of that, I didn't find any silvery strands.

I also scraped back a couple of sections where the insulation had deteriorated enough to become inflexible. The copper wires looked very dull, with a light, fine powder over the surface. Interestingly the powder had a different hue dependant on insulation colour. Blue/green for neutral and brown (almost indistinguishable from the copper itself) for active.

Of the four sockets originally in this enclosure, two had more serious rust on the mounting brackets, one had a small level of oxidisation and one had none at all. For the two sockets with the most rust, the rusted portion of the bracket was underneath the silicone bead that had been run around the base of the socket. All four sockets were in fairly close proximity of each other.
 

apprenticegnome

Active Member
Silicones that have a strong vinegar like smell are generally acid cure as opposed to neutral cure silicones. When I've used silicones building and repairing aquariums in the past they were of the acid cure variety and commonly bought from any hardware. I only found out when looking at repairing our caravan about neutral cure v's acidic cure and some of the pitfalls for either type.
 

Bluetongue1

APS Veteran
APS Veteran
[MENTION=25504]apprenticegnome[/MENTION]. My apologies for not having responded to your earlier post. You are quite correct. Anyone who has mended or constructed an aquarium would be well aware of the ‘vinegar smell’ the silicone used develops when curing. This is because this type of silicone sealant/adhesive produces acetic acid. Other types produce neutral chemicals and a very few produce alkaline chemicals.

If the sealant used in this case produced a chemical capable of reacting with the metallic parts of the light battens, then one would expect each area where the silicon was in contact with the metal of the batten to be affected. This is clearly not the case.
 

pythoninfinite

APS Veteran
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Neutral-cure silicones were produced initially for the roofing and plumbing industries because the acetic acid cure products destroy the galvanizing or zincalume coatings on steel roofing or guttering products. As far as silicones in general are concerned, there are new products coming onto the market every year, so there's no such thing as a "general" silicone these days, most of them have specific applications for use in particular circumstances, so it's up to the user to ensure the correct choices are made. This is particularly important when using them as adhesives because not all of them adhere well to all surfaces, especially for long-term applications.

Jamie
 
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