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Post by mrfatso on Jul 30, 2017 7:59:52 GMT
Around here we used to have reinforced concrete lamposts, until they corroded and had to be replaced.
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Post by the light works on Jul 30, 2017 14:13:38 GMT
Could the concrete itself be responsible for the corrosion? possible, but not probable. rebar is not usually corrosion protected, and exposed rebar is usually corroded worse than embedded rebar. I think the concrete seals tightly enough to help protect the metal. |
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Post by GTCGreg on Jul 30, 2017 15:26:41 GMT
Could the concrete itself be responsible for the corrosion? possible, but not probable. rebar is not usually corrosion protected, and exposed rebar is usually corroded worse than embedded rebar. I think the concrete seals tightly enough to help protect the metal. One of the houses I lived in growing up had a concrete lamp post out front. Eventually, all of the concrete broke away near the bottom exposing the rebar. They eventually replaced all of the old incandescent lamp post with mercury vapor type. An interesting side fact on the old incandescent lighting system is that all the bulbs were wired in series and fed directly by the 7,000 volt feeder through a constant current regulator. If you unscrewed a bulb, you would end up with 7kV across the socket. To change a bulb, you would pull the entire socket straight out, which would then short the circuit preventing the 7,000 volts and also allow the rest of the street lights on the circuit to continue to operate. If a bulb would burn out, the socket was self-shorting to keep the rest of the lights on. Sort of like Christmas lights. It was very dangerous when one of these lamp posts would get knocked over or fall on it's own because if the wires broke, you could be exposed to 7,000 volts. |
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Post by silverdragon on Jul 30, 2017 16:09:01 GMT
Hmmm... erm... Well.... I suppose having 480~240 V A/C running through street furniture would be "Bad"?... AFAIK, All street furniture must be "Double insulated" at the power outlet AND earthed, therefore, belt and braces, so as not to have a build up of static or any other kind of electricity.... especially on those parts small children can lick in the cold to stick their tongues to it?.. The locks on the base of the things are extremely difficult to get into if you dont have the right tools. And after the questions above, ya think ya may wanna stop them doing that?.. But saying that. Question for any that may know, and how would you find out anyway, just how many lightning strikes happen on street furniture daily around the world, and if you get a billion volt courtesy of Mjolnir, would it A] blow the bloody circuit, B] cause damage, or C] both?.. Does the mere fact that they have electrical currents and therefore possibly a [possible?] magnetic field through them make them attractive to rust/oxidisation?. What causes corrosion isn't the magnetic field, it's a voltage across the contact point of dissimilar metals. And for this voltage to happen, you often don't need an outside voltage source at all. If you have two different metals touching each other, and any type of moisture gets to the contact point, it creates a battery that can cause current to flow through the contact point and erodes the metals. DOH!... thwak across the back of me own heed there, why didnt I get that?... Yep, yer right, ... Ok, so, if its a difference in metals, hows that work at the base of a [for instance] all one metal lamp post sunk into concrete?.. The lamp stand outside my house is sunk down a hole, back-filled with concrete, and tarmac pavement over the top, its one piece Aluminium sheet welded metal all the way to the plastic lamp housing?.. how would any moisture react that way with that type of build?. I may be able to answer that...?.. the connection must have had an earth to the body of the ambulance as well as the three-prong live-neutral-earth to the external power source, or, if not, the lightning may have arced across between the two, and yea gods know what happens in the "Plasma" state of all materials when struck by a sizeable blast?.. We know more about the surface of the sun than we know about Lightning... But we are catching on fast. VERY fast. I know this, Astrophysicists call Hydrogen Helium and maybe one or two other gases "Gas", the rest are all called metals... Why?. One reason given, just one of a long list, Because the definition of metal is one that conducts electricity... You may ask "But solid basalt rock doesnt conduct electricity"... Depends on how much you heat it up. In a gaseous form, that which makes Basalt, conducts electricity, especially when its turned to Plasma by a lightning bolt?.. They have far more educated reasons than JUST that, but I dont have the space to post all that can be found on the subject... And as one that has seen lightning "dance" around an all wooden flag post with nothing but a hemp rope anywhere near it, I have to ask, how can wood conduct lightning?.. I know, the answer is "Complicated" |
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Post by silverdragon on Jul 30, 2017 16:14:29 GMT
Could the concrete itself be responsible for the corrosion? BADUM!.... You have a point. Take a slab of concrete and poor "Battery acid" on it like I did when I first changed a battery at the age of 16 on my first car.. It fell off the bumper... I have no idea why I thought that would be a good resting place for the old battery at that time, but it fell. Anyway, the battery acid, weak as it was, still fizzed its way through the concrete surface until my Dad threw kitty litter sawdust all over it. I may make a guess that maybe on a warm day that any type of urine, dog or cat, may evaporate a little, and become a stronger acid, that may well cause a reaction with the concrete, and create maybe an environment where metal would oxidise quicker?.. This may also be why all lamp posts around here are surrounded with Tarmac, to prevent that happening maybe?. |
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Post by the light works on Jul 30, 2017 16:33:11 GMT
What causes corrosion isn't the magnetic field, it's a voltage across the contact point of dissimilar metals. And for this voltage to happen, you often don't need an outside voltage source at all. If you have two different metals touching each other, and any type of moisture gets to the contact point, it creates a battery that can cause current to flow through the contact point and erodes the metals. DOH!... thwak across the back of me own heed there, why didnt I get that?... Yep, yer right, ... Ok, so, if its a difference in metals, hows that work at the base of a [for instance] all one metal lamp post sunk into concrete?.. The lamp stand outside my house is sunk down a hole, back-filled with concrete, and tarmac pavement over the top, its one piece Aluminium sheet welded metal all the way to the plastic lamp housing?.. how would any moisture react that way with that type of build?. I may be able to answer that...?.. the connection must have had an earth to the body of the ambulance as well as the three-prong live-neutral-earth to the external power source, or, if not, the lightning may have arced across between the two, and yea gods know what happens in the "Plasma" state of all materials when struck by a sizeable blast?.. We know more about the surface of the sun than we know about Lightning... But we are catching on fast. VERY fast. I know this, Astrophysicists call Hydrogen Helium and maybe one or two other gases "Gas", the rest are all called metals... Why?. One reason given, just one of a long list, Because the definition of metal is one that conducts electricity... You may ask "But solid basalt rock doesnt conduct electricity"... Depends on how much you heat it up. In a gaseous form, that which makes Basalt, conducts electricity, especially when its turned to Plasma by a lightning bolt?.. They have far more educated reasons than JUST that, but I dont have the space to post all that can be found on the subject... And as one that has seen lightning "dance" around an all wooden flag post with nothing but a hemp rope anywhere near it, I have to ask, how can wood conduct lightning?.. I know, the answer is "Complicated" you're not completely of base about the magnetics - the streetlight wiring causes a rotating magnetic field, which then interacts with the light pole to produce an inducted voltage. as far as conducting electricity, there are two basic charateristics: conductivity, and dielectric strength. a material can be conductive or nonconductive, on a scale of resistance, and nonconductive material, simply doesn't carry electricity well. dielectric material, on the other hand, is measured on its ability to block electricity - an what distinguishes it is that it has a breakdown voltage - which is the voltage at which it becomes conductive. for example, thermoplastic, and most other common "insulator" materials have a breakdown rating of 600 volts. - some may have an actual breakdown voltage higher than 600V, but that is our standard division between normal voltage, and high voltage. - anything over 600V becomes "don't touch it with a ten foot pole" safety requirements. |
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Post by Cybermortis on Jul 30, 2017 18:03:14 GMT
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Post by silverdragon on Jul 31, 2017 7:43:28 GMT
Got a suggestion... Lump of Zink.
Ships hulls have a lump of zink on them as a "Sacrificial" to deal with all the "Active" voltage.
its called Galvanic anode?..
Is it possible to test this by placing such on a lamp post and see if it still degrades.
Has someone somewhere thought of this before and I am just re-inventing the square wheel here?.
I am also having a slight problem with how would the crew do this "In seven days"... some of these tests may take a while?.
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Post by the light works on Jul 31, 2017 13:49:26 GMT
Got a suggestion... Lump of Zink. Ships hulls have a lump of zink on them as a "Sacrificial" to deal with all the "Active" voltage. its called Galvanic anode?.. Is it possible to test this by placing such on a lamp post and see if it still degrades. Has someone somewhere thought of this before and I am just re-inventing the square wheel here?. I am also having a slight problem with how would the crew do this "In seven days"... some of these tests may take a while?. here, our steel posts are all galvanized, and any high quality aluminum is anodized - which I presume implies that something is applied to act as the anode. |
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Post by GTCGreg on Jul 31, 2017 14:46:29 GMT
here, our steel posts are all galvanized, and any high quality aluminum is anodized - which I presume implies that something is applied to act as the anode. When aluminum is "anodized", the entire piece of aluminum is placed in an acid bath and electrical current is then passed through the acid from a cathode. The aluminum acts as the anode and thus the name anodized. In the process, a very heavy layer of aluminum oxide (aluminum rust) forms on the surface of the aluminum piece that creates a strong, but porous coating that protects the aluminum. Because the oxide is porous, paint or dye can be added to the process which gives the aluminum a very durable color coating. After the process is completed, the aluminum piece is nor longer an anode of any type, but retains the name "anodized" because it was once the anode in the process. |
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Post by the light works on Jul 31, 2017 15:28:32 GMT
here, our steel posts are all galvanized, and any high quality aluminum is anodized - which I presume implies that something is applied to act as the anode. When aluminum is "anodized", the entire piece of aluminum is placed in an acid bath and electrical current is then passed through the acid from a cathode. The aluminum acts as the anode and thus the name anodized. In the process, a very heavy layer of aluminum oxide (aluminum rust) forms on the surface of the aluminum piece that creates a strong, but porous coating that protects the aluminum. Because the oxide is porous, paint or dye can be added to the process which gives the aluminum a very durable color coating. After the process is completed, the aluminum piece is nor longer an anode of any type, but retains the name "anodized" because it was once the anode in the process. ah. but aluminum oxide created in that manner does provide corrosion protection, it seems. |
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Post by GTCGreg on Jul 31, 2017 15:40:28 GMT
When aluminum is "anodized", the entire piece of aluminum is placed in an acid bath and electrical current is then passed through the acid from a cathode. The aluminum acts as the anode and thus the name anodized. In the process, a very heavy layer of aluminum oxide (aluminum rust) forms on the surface of the aluminum piece that creates a strong, but porous coating that protects the aluminum. Because the oxide is porous, paint or dye can be added to the process which gives the aluminum a very durable color coating. After the process is completed, the aluminum piece is nor longer an anode of any type, but retains the name "anodized" because it was once the anode in the process. ah. but aluminum oxide created in that manner does provide corrosion protection, it seems. Yes it does. The reason is because it is bonded very strongly with the aluminum atoms underneath it. Unlike the aluminum oxide that forms from normal oxidation that just lays on the surface. This is why your hands get a black coating on them when you handle a piece of non-anodized aluminum. That black stuff on your hands is aluminum oxide that got wiped off the surface of the aluminum when you handled it. The aluminum oxide that was bonded during the anodization process will not wipe off and protects the aluminum under it. |
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Post by the light works on Jul 31, 2017 15:46:24 GMT
ah. but aluminum oxide created in that manner does provide corrosion protection, it seems. Yes it does. The reason is because it is bonded very strongly with the aluminum atoms underneath it. Unlike the aluminum oxide that forms from normal oxidation that just lays on the surface. This is why your hands get a black coating on them when you handle a piece of non-anodized aluminum. That black stuff on your hands is aluminum oxide that got wiped off the surface of the aluminum when you handled it. The aluminum oxide that was bonded during the anodization process will not wipe off and protects the aluminum under it. but on solid aluminum, if the surface is scratched, the oxide layer that develops still seals out further oxidation. interesting stuff, aluminum. |
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Post by GTCGreg on Jul 31, 2017 15:56:49 GMT
Yes it does. The reason is because it is bonded very strongly with the aluminum atoms underneath it. Unlike the aluminum oxide that forms from normal oxidation that just lays on the surface. This is why your hands get a black coating on them when you handle a piece of non-anodized aluminum. That black stuff on your hands is aluminum oxide that got wiped off the surface of the aluminum when you handled it. The aluminum oxide that was bonded during the anodization process will not wipe off and protects the aluminum under it. but on solid aluminum, if the surface is scratched, the oxide layer that develops still seals out further oxidation. interesting stuff, aluminum. Yes, as long as it doesn't get wiped off. Because it's just laying there, it can get washed off by corrosive liquids (dog pee?) that then can attack the aluminum underneath it. Another interesting protection that the anodization layer provides is that it is an electrical insulator. It can keep an electrical current from flowing through the aluminum that may also corrode the surface. This is why you never find anodized aluminum used as bus bars in electrical equipment. If aluminum is used, it is not anodized. If you need to make a good electrical connection to anodized aluminum, you have to grind away the oxide layer. Of course, as you know, the normally forming aluminum oxide can also cause electrical connection problems. |
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Post by the light works on Jul 31, 2017 16:08:51 GMT
but on solid aluminum, if the surface is scratched, the oxide layer that develops still seals out further oxidation. interesting stuff, aluminum. Yes, as long as it doesn't get wiped off. Because it's just laying there, it can get washed off by corrosive liquids (dog pee?) that then can attack the aluminum underneath it. Another interesting protection that the anodization layer provides is that it is an electrical insulator. It can keep an electrical current from flowing through the aluminum that may also corrode the surface. This is why you never find anodized aluminum used as bus bars in electrical equipment. If aluminum is used, it is not anodized. If you need to make a good electrical connection to anodized aluminum, you have to grind away the oxide layer. Of course, as you know, the normally forming aluminum oxide can also cause electrical connection problems. trying to smooth up pitted aluminum busbars enough to make solid contact with a breaker long enough to get a new panel ordered is always a frustrating project. of course, the cheapskates who buy panels with aluminum buses also buy them undersized. |
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Post by GTCGreg on Jul 31, 2017 16:31:22 GMT
trying to smooth up pitted aluminum busbars enough to make solid contact with a breaker long enough to get a new panel ordered is always a frustrating project. of course, the cheapskates who buy panels with aluminum buses also buy them undersized. You would think that with all the problems we have with making good electrical contact with aluminum, it wouldn't be allowed for use in electrical distribution systems. It would be great if it wasn't for the oxidation problem. It's intresting in that in the order of best conductivity, you have silver, gold, copper and then aluminum. The nice thing about gold is that it doesn't oxidize. The nice feature of silver is that, while it does oxidize easily, its oxide is conductive. Of course, we know why gold and silver isn't used as bus bars, but they are often used as a surface plating on electrical connections and contacts. Maybe we just need to plate our lamp post bottoms with gold. That would cut down on corrosion. Of course, they may go missing for other reasons. |
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Post by the light works on Aug 1, 2017 0:31:53 GMT
trying to smooth up pitted aluminum busbars enough to make solid contact with a breaker long enough to get a new panel ordered is always a frustrating project. of course, the cheapskates who buy panels with aluminum buses also buy them undersized. You would think that with all the problems we have with making good electrical contact with aluminum, it wouldn't be allowed for use in electrical distribution systems. It would be great if it wasn't for the oxidation problem. It's intresting in that in the order of best conductivity, you have silver, gold, copper and then aluminum. The nice thing about gold is that it doesn't oxidize. The nice feature of silver is that, while it does oxidize easily, its oxide is conductive. Of course, we know why gold and silver isn't used as bus bars, but they are often used as a surface plating on electrical connections and contacts. Maybe we just need to plate our lamp post bottoms with gold. That would cut down on corrosion. Of course, they may go missing for other reasons. actually, as I recall, gold is less conductive than copper - but it doesn't oxidize. |
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Post by GTCGreg on Aug 1, 2017 1:23:42 GMT
You would think that with all the problems we have with making good electrical contact with aluminum, it wouldn't be allowed for use in electrical distribution systems. It would be great if it wasn't for the oxidation problem. It's intresting in that in the order of best conductivity, you have silver, gold, copper and then aluminum. The nice thing about gold is that it doesn't oxidize. The nice feature of silver is that, while it does oxidize easily, its oxide is conductive. Of course, we know why gold and silver isn't used as bus bars, but they are often used as a surface plating on electrical connections and contacts. Maybe we just need to plate our lamp post bottoms with gold. That would cut down on corrosion. Of course, they may go missing for other reasons. actually, as I recall, gold is less conductive than copper - but it doesn't oxidize. You're right. I think it goes Silver is best, copper is second, gold is third, and aluminum is fourth with everything else pretty far down the list. |
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Post by the light works on Aug 1, 2017 4:07:04 GMT
actually, as I recall, gold is less conductive than copper - but it doesn't oxidize. You're right. I think it goes Silver is best, copper is second, gold is third, and aluminum is fourth with everything else pretty far down the list. and copper is cheaper and aluminum is much cheaper. |
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