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> Copper is used for 12 and 14 gauge branch circuits. Aluminum branch circuits are currently strongly discouraged. Maybe you're already saying this: there was

> Copper is used for 12 and 14 gauge branch circuits. Aluminum branch circuits are currently strongly discouraged. Maybe you're already saying this: there was a period (maybe ~70s) where aluminum was used for household wiring because of the advantages you mention. Unfortunately it oxidizes resulting in higher resistance leading to heat and potentially fire at connections. Where I am, insurers ask you if you have aluminum wiring when you buy a house (and penalize you for it), and it is generally regarded as a failed experiment.

SoftTalker 4y ago
Yep. Aluminum wiring can be safe, but you need to coat all the connections with anti-oxidizing grease. And even at at that, I don't know how long it lasts. Copper pipe for water is often specified by code in commercial construction. I've heard this is due to lobbying by plumber's unions but not sure about that. Most residential construction will use CPVC or PEX these days.
- toomuchtodo 4y ago
  I am a huge fan of PEX from a cost and longevity perspective (it can withstand some freezing of water without bursting), but copper is cool for its anti microbial and similar chemical resistance properties. If money was no object, I’d spec copper over plastics for water supply if I expected the structure to exist for 50-100 years. Disposable structures? Plastics all the way, dump the whole thing in a plasma gasifier upon retirement.
  - amluto 4y ago
    I’m less convinced. Copper is susceptible to its own failure modes. Water moving too fast in a copper pipe can erode the pipe, and “too fast” is quite slow, especially for hot water. If you want hot water quickly, you want the fastest practical speed, which means the smallest practical pipe, and you can easily run into the limitations of copper. PEX and CPVC tolerate considerable higher water velocity. (I think this is because copper’s passive layer can be scoured away, whereas plastic pipes don’t need a passive layer.) If you have well water or water from anywhere other than a utility that controls the chemistry correctly, the water can dissolve your pipes. The rainwater from my roof makes copper instantly shiny, which is a bad sign for the copper.
    - themitigating 4y ago
      Solder doesn't last forever right? When did we start using it over iron?
      - SoftTalker 4y ago
        I had iron pipe in my first house. Water was rusty when we got home after a weekend away. Got tired of rust stained sinks and laundry. Ripped it all out and replaced it with CPVC (this was before PEX was really widely available). Never had trouble after that.
    - r3trohack3r 4y ago
      Not to mention water itself is horribly corrosive. Pure water will strip copper pipes. That’s the real reason fluoride was added to tap water: 1) it was cheap 2) it was safe to drink 3) it kept the water from eating the city’s pipes. We had a city in Illinois do whole city RO and advertise the cleanest water in the country. Well it was the cleanest water going into the pipes, but if you own a house in that city the water coming out of your tap is full of old pipe!
      - alfor 4y ago
        Where did you get the info about fluoride?
        r3trohack3r 4y ago
        From an ex-well driller - which I yield isn’t the most reliable source. I haven’t been able to find a source since posting this. I may have my facts backwards! The closest I have is this CDC report saying it reduces corrosiveness: https://www.cdc.gov/fluoridation/engineering/corrosion.htm https://www.cdc.gov/fluoridation/engineering/corrosion.htm My understanding is that, if you take fluoride out of the water, you’ll need to replace it with something or the water will replace it itself (aka eat the pipe). That obviously doesn’t mean fluoride was originally added for that reason though.
  - nanidin 4y ago
    > Plastics all the way, dump the whole thing in a plasma gasifier upon retirement. Wouldn't it be better to sequester the carbon in a landfill rather than return it to the atmosphere?
    - NullPrefix 4y ago
      Landfill requires area. Plasma gasifier produces energy. Here's all the motivation why.
      - MereInterest 4y ago
        I don't think that's quite a fair comparison. Option A: Con, landfill space. Option B: Pro, energy generation to burn. Con, energy cost of capturing carbon. Con, storage space of captured carbon.
        hnick 4y ago
        I think to be truly fair Option A has to consider the energy generation you will have to do elsewhere to make up the difference, which may or may not be carbon neutral - or to flip it, the energy generation you won't have to do due to Option B. So it really depends on the energy generation landscape you are within.
  - poulsbohemian 4y ago
    I'm curious why you would choose copper over PEX. It seems like PEX is really the best choice available these days in terms of near infinite lifespan, easy to work with, and affordable.
    - toomuchtodo 4y ago
      https://www.bobvila.com/articles/pex-vs-copper/ https://www.bobvila.com/articles/pex-vs-copper/ > It’s tough to beat copper pipes for longevity, which on average last 50 to 70 years, compared to PEX, which has an expected lifespan of 30 to 50 years. PEX’s life expectancy can be shortened by the use of extremely hot household water (180 degrees Fahrenheit or higher) or if the water in the home contains high levels of chlorine. > Copper’s life can be shortened by highly acidic water. When installed under typical conditions (i.e., your home is connected to a municipal water system), copper can be expected to outlast PEX by about 20 years. If you’re on a private well, have your water tested prior to retrofitting your water supply system. Local County Extension Offices can test well water to determine whether it’s high in acid or chlorine. I’m a buy it for life sort of person, and will pay a premium for longevity. Future myself or others will thank me (buying or building something that will outlive me? Plant trees whose shade I’ll never sit in and all that jazz)
      - poulsbohemian 4y ago
        Well now you've sent me down a whole other rabbit hole wondering about who these people are who keep their hot water at 180 degrees or about how much chlorine constitutes high levels. Fascinating stuff, thanks for the insight.
      - ericd 4y ago
        Yep, if you ever see bluish rings in your toilets, and you have copper piping, check your water pH, that might be part of your home's plumbing that's now ringing the porcelain.
    - alliao 4y ago
      PEX is cheap and cheerful, but with plenty of downsides, PP is actually pretty good just expensive
  - themitigating 4y ago
    Compression fitting will last longer than copper. If a copper fitting is done wrong it can pit. I'm going to be honest here and tell you I can't find sources for this but I thought I've seen it before in research - Copper lasts 50-60 years. I believe that's type L which is used in the wall in homes in the US. The skill required to create a high quality copper joint takes time and a person may still make mistakes. A PEX compression fitting is basically just closing a tool. The probability of mistakes is lower. I'm not familiar with the possibility of contamination in pex, is this due to the material?
    - throwaway9870 4y ago
      I am fairly sure type M is used in normal residential construction. L is heavier and use for more underground or commercial applications. You can quickly tell the difference because M has red writing on it, while L have blue. The problem is there are no "L" fittings and the normal fittings used for L copper can be quite poor. For this reason and others, some people like ProPress fittings which are very high quality (and expensive).
  - jsjohnst 4y ago
    > [PEX] can withstand some freezing of water without bursting I learned that the hard way last year. Had PEX water lines hard freeze during the crazy February weather in Texas area last year. Thankfully no burst pipes!
- Ottolay 4y ago
  There are also a new aluminum alloys (aa-8000) with better mechanical properties. The biggest issue is that that the trades/DIYers need to learn new processes. Treating aluminum wiring like copper wiring is a disaster. Also need to overcome the stigma from the aluminum experiment 50 years ago. It makes a ton of sense to switch to aluminum in housing though. For the same current capability the wire is significantly cheaper, lighter, and stronger.
- lazide 4y ago
  Aluminum also has issues with heat expansion and contraction causing connections to loosen faster. With properly rated connectors, not a problem, but not all are, and not everyone knows it's a thing. Copper pipe is much more durable as long as the local water isn't acidic, which is rare. CPVC has had a number of issues over the years (including leaching of chemicals and brittleness over time), and PEX is still relatively unproven. It's predecessor product had huge insurance claims due to failing connections after 10+ years.
  - m-p-3 4y ago
    > It's predecessor product had huge insurance claims due to failing connections after 10+ years. Those were PB/Polybutylene pipes.
    - SoftTalker 4y ago
      Mostly used in manufactured and mobile homes IIRC? Those aren't built to last more than 10-15 years anyway.
      - m-p-3 4y ago
        My home currently has those all over, built in 1992 in Canada. Not a mobile or manufactured home.
- sgc 4y ago
  Pex gets eaten through by rats and then you get to replace 20% of your house if you don't catch it in time. Copper for water is better, or you could run PEX in CSST conduit everywhere (never seen or heard of it). I don't know enough about rats and CPVC, but it seems a bit safer at least. But you will get rats, it's just a question of when.
  - petre 4y ago
    What about PPR? It handles freezing quite well, it's joined by thremsl fusion and there are versions with fiberglass or aluminium insertion.
    - sgc 4y ago
      It looks good as well. At the same time, all these plastic materials are petroleum based products we are piping our drinking water through, although we likely have no choice for this century at least.
  - kragen 4y ago
    Why doesn't anyone run PEX in CSST conduit (flexible galvanized steel, for those who don't know, as is commonly used to protect wiring) if this is such a problem? Flexible conduit is a hell of a lot cheaper than copper pipe, easier to bend and connect too.
    - sgc 4y ago
      Probably because the junction boxes would be unwieldy more than anything.
  - ChoGGi 4y ago
    > But you will get rats, it's just a question of when. When? I live in Alberta. (okay a bit tongue in cheek)
- ars 4y ago
  > but you need to coat all the connections with anti-oxidizing grease Actually, no you don't. Only wires from like 30 years ago need that. Modern aluminum wires do NOT need the coating. In fact in some places you will fail inspection if you add the coating. Most people have not updated their knowledge on this, since they don't work in the industry.
- dillondoyle 4y ago
  I buy the pipe fitters union power. Just read an article in a local paper about banning gas connections in new housing. Had a direct quote from the union saying they aren't inherently opposed per se, but need ___ $$ to offset any job losses. And then next graph mentioned that union was part of a lobbying pac thing fighting for the status quo
  - Scoundreller 4y ago
    How are they harmed by gas connections?
    - dillondoyle 4y ago
      They would be harmed by banning gas connections, because it's a lot less pipe fitting they could do.
amluto 4y ago
Indeed. Maybe a new generation of aluminum wire could be better. But for big feeder wires, it’s a different story. Compare: 2 AWG XHHW-2 Al: 0.358 inches OD, 0.081 lbs per ft, $0.90/ft 4 AWG XHHW-2 Cu: 0.33 inches OD, 0.129 lbs per ft, $1.78/ft I know which one I would pick under most circumstances. And insurance companies are just fine with the aluminum option.
- dboreham 4y ago
  USA could also transition to a proper mains voltage like much of the rest of the planet.
  - chiph 4y ago
    230/240v does have it's advantages, primarily being able to use smaller diameter wire for the same current carrying capacity. But 50 Hz as a system frequency is just wrong. It results in oddities like running your railroad at 16-2/3 Hz.
    - eru 4y ago
      I'm not sure what's so odd about running your railroad at 50/3 Hz? Do you not like rational numbers? (I guess you are talking about three-phase power in general, or is there anything special about railroads?) In practice, just like everything in engineering, you don't run your grid at 50 Hz nor your railroad at 50/3 Hz. You run the grid at some frequency that varies slightly around 50Hz. There's always engineering tolerances. So even if you don't like rational numbers, it doesn't really matter whether you run the railroads at 50/3 +-0.01 Hz, or at 16.66 +-0.01 Hz. (I don't know how tight the tolerances are in practice here. It doesn't matter for the argument.)
      - lazide 4y ago
        Rational numbers are a lot more work than integers. Also, 60 is a common base for several things (degrees, time), which interact with the grid in numerous ways. It’s convenient to have them match.
oakwhiz 4y ago
Aluminum is a good choice for 0000 AWG and above.
freeqaz 4y ago
It also expands/contracts more than copper which can cause screws to come loose and trigger sparks that set fire to the inside of your walls. (Source: A home inspection report from a house I looked at buying a few years ago.)

SoftTalker 4y ago

Yep. Aluminum wiring can be safe, but you need to coat all the connections with anti-oxidizing grease. And even at at that, I don't know how long it lasts. Copper pipe for water is often specified by code in commercial construction. I've heard this is due to lobbying by plumber's unions but not sure about that. Most residential construction will use CPVC or PEX these days.

toomuchtodo 4y ago
I am a huge fan of PEX from a cost and longevity perspective (it can withstand some freezing of water without bursting), but copper is cool for its anti microbial and similar chemical resistance properties. If money was no object, I’d spec copper over plastics for water supply if I expected the structure to exist for 50-100 years. Disposable structures? Plastics all the way, dump the whole thing in a plasma gasifier upon retirement.
- amluto 4y ago
  I’m less convinced. Copper is susceptible to its own failure modes. Water moving too fast in a copper pipe can erode the pipe, and “too fast” is quite slow, especially for hot water. If you want hot water quickly, you want the fastest practical speed, which means the smallest practical pipe, and you can easily run into the limitations of copper. PEX and CPVC tolerate considerable higher water velocity. (I think this is because copper’s passive layer can be scoured away, whereas plastic pipes don’t need a passive layer.) If you have well water or water from anywhere other than a utility that controls the chemistry correctly, the water can dissolve your pipes. The rainwater from my roof makes copper instantly shiny, which is a bad sign for the copper.
  - themitigating 4y ago
    Solder doesn't last forever right? When did we start using it over iron?
    - SoftTalker 4y ago
      I had iron pipe in my first house. Water was rusty when we got home after a weekend away. Got tired of rust stained sinks and laundry. Ripped it all out and replaced it with CPVC (this was before PEX was really widely available). Never had trouble after that.
  - r3trohack3r 4y ago
    Not to mention water itself is horribly corrosive. Pure water will strip copper pipes. That’s the real reason fluoride was added to tap water: 1) it was cheap 2) it was safe to drink 3) it kept the water from eating the city’s pipes. We had a city in Illinois do whole city RO and advertise the cleanest water in the country. Well it was the cleanest water going into the pipes, but if you own a house in that city the water coming out of your tap is full of old pipe!
    - alfor 4y ago
      Where did you get the info about fluoride?
      - r3trohack3r 4y ago
        From an ex-well driller - which I yield isn’t the most reliable source. I haven’t been able to find a source since posting this. I may have my facts backwards! The closest I have is this CDC report saying it reduces corrosiveness: https://www.cdc.gov/fluoridation/engineering/corrosion.htm https://www.cdc.gov/fluoridation/engineering/corrosion.htm My understanding is that, if you take fluoride out of the water, you’ll need to replace it with something or the water will replace it itself (aka eat the pipe). That obviously doesn’t mean fluoride was originally added for that reason though.
- nanidin 4y ago
  > Plastics all the way, dump the whole thing in a plasma gasifier upon retirement. Wouldn't it be better to sequester the carbon in a landfill rather than return it to the atmosphere?
  - NullPrefix 4y ago
    Landfill requires area. Plasma gasifier produces energy. Here's all the motivation why.
    - MereInterest 4y ago
      I don't think that's quite a fair comparison. Option A: Con, landfill space. Option B: Pro, energy generation to burn. Con, energy cost of capturing carbon. Con, storage space of captured carbon.
      - hnick 4y ago
        I think to be truly fair Option A has to consider the energy generation you will have to do elsewhere to make up the difference, which may or may not be carbon neutral - or to flip it, the energy generation you won't have to do due to Option B. So it really depends on the energy generation landscape you are within.
- poulsbohemian 4y ago
  I'm curious why you would choose copper over PEX. It seems like PEX is really the best choice available these days in terms of near infinite lifespan, easy to work with, and affordable.
  - toomuchtodo 4y ago
    https://www.bobvila.com/articles/pex-vs-copper/ https://www.bobvila.com/articles/pex-vs-copper/ > It’s tough to beat copper pipes for longevity, which on average last 50 to 70 years, compared to PEX, which has an expected lifespan of 30 to 50 years. PEX’s life expectancy can be shortened by the use of extremely hot household water (180 degrees Fahrenheit or higher) or if the water in the home contains high levels of chlorine. > Copper’s life can be shortened by highly acidic water. When installed under typical conditions (i.e., your home is connected to a municipal water system), copper can be expected to outlast PEX by about 20 years. If you’re on a private well, have your water tested prior to retrofitting your water supply system. Local County Extension Offices can test well water to determine whether it’s high in acid or chlorine. I’m a buy it for life sort of person, and will pay a premium for longevity. Future myself or others will thank me (buying or building something that will outlive me? Plant trees whose shade I’ll never sit in and all that jazz)
    - poulsbohemian 4y ago
      Well now you've sent me down a whole other rabbit hole wondering about who these people are who keep their hot water at 180 degrees or about how much chlorine constitutes high levels. Fascinating stuff, thanks for the insight.
    - ericd 4y ago
      Yep, if you ever see bluish rings in your toilets, and you have copper piping, check your water pH, that might be part of your home's plumbing that's now ringing the porcelain.
  - alliao 4y ago
    PEX is cheap and cheerful, but with plenty of downsides, PP is actually pretty good just expensive
- themitigating 4y ago
  Compression fitting will last longer than copper. If a copper fitting is done wrong it can pit. I'm going to be honest here and tell you I can't find sources for this but I thought I've seen it before in research - Copper lasts 50-60 years. I believe that's type L which is used in the wall in homes in the US. The skill required to create a high quality copper joint takes time and a person may still make mistakes. A PEX compression fitting is basically just closing a tool. The probability of mistakes is lower. I'm not familiar with the possibility of contamination in pex, is this due to the material?
  - throwaway9870 4y ago
    I am fairly sure type M is used in normal residential construction. L is heavier and use for more underground or commercial applications. You can quickly tell the difference because M has red writing on it, while L have blue. The problem is there are no "L" fittings and the normal fittings used for L copper can be quite poor. For this reason and others, some people like ProPress fittings which are very high quality (and expensive).
- jsjohnst 4y ago
  > [PEX] can withstand some freezing of water without bursting I learned that the hard way last year. Had PEX water lines hard freeze during the crazy February weather in Texas area last year. Thankfully no burst pipes!
Ottolay 4y ago
There are also a new aluminum alloys (aa-8000) with better mechanical properties. The biggest issue is that that the trades/DIYers need to learn new processes. Treating aluminum wiring like copper wiring is a disaster. Also need to overcome the stigma from the aluminum experiment 50 years ago. It makes a ton of sense to switch to aluminum in housing though. For the same current capability the wire is significantly cheaper, lighter, and stronger.
lazide 4y ago
Aluminum also has issues with heat expansion and contraction causing connections to loosen faster. With properly rated connectors, not a problem, but not all are, and not everyone knows it's a thing. Copper pipe is much more durable as long as the local water isn't acidic, which is rare. CPVC has had a number of issues over the years (including leaching of chemicals and brittleness over time), and PEX is still relatively unproven. It's predecessor product had huge insurance claims due to failing connections after 10+ years.
- m-p-3 4y ago
  > It's predecessor product had huge insurance claims due to failing connections after 10+ years. Those were PB/Polybutylene pipes.
  - SoftTalker 4y ago
    Mostly used in manufactured and mobile homes IIRC? Those aren't built to last more than 10-15 years anyway.
    - m-p-3 4y ago
      My home currently has those all over, built in 1992 in Canada. Not a mobile or manufactured home.
sgc 4y ago
Pex gets eaten through by rats and then you get to replace 20% of your house if you don't catch it in time. Copper for water is better, or you could run PEX in CSST conduit everywhere (never seen or heard of it). I don't know enough about rats and CPVC, but it seems a bit safer at least. But you will get rats, it's just a question of when.
- petre 4y ago
  What about PPR? It handles freezing quite well, it's joined by thremsl fusion and there are versions with fiberglass or aluminium insertion.
  - sgc 4y ago
    It looks good as well. At the same time, all these plastic materials are petroleum based products we are piping our drinking water through, although we likely have no choice for this century at least.
- kragen 4y ago
  Why doesn't anyone run PEX in CSST conduit (flexible galvanized steel, for those who don't know, as is commonly used to protect wiring) if this is such a problem? Flexible conduit is a hell of a lot cheaper than copper pipe, easier to bend and connect too.
  - sgc 4y ago
    Probably because the junction boxes would be unwieldy more than anything.
- ChoGGi 4y ago
  > But you will get rats, it's just a question of when. When? I live in Alberta. (okay a bit tongue in cheek)
ars 4y ago
> but you need to coat all the connections with anti-oxidizing grease Actually, no you don't. Only wires from like 30 years ago need that. Modern aluminum wires do NOT need the coating. In fact in some places you will fail inspection if you add the coating. Most people have not updated their knowledge on this, since they don't work in the industry.
dillondoyle 4y ago
I buy the pipe fitters union power. Just read an article in a local paper about banning gas connections in new housing. Had a direct quote from the union saying they aren't inherently opposed per se, but need ___ $$ to offset any job losses. And then next graph mentioned that union was part of a lobbying pac thing fighting for the status quo
- Scoundreller 4y ago
  How are they harmed by gas connections?
  - dillondoyle 4y ago
    They would be harmed by banning gas connections, because it's a lot less pipe fitting they could do.

amluto 4y ago

Indeed. Maybe a new generation of aluminum wire could be better. But for big feeder wires, it’s a different story. Compare: 2 AWG XHHW-2 Al: 0.358 inches OD, 0.081 lbs per ft, $0.90/ft 4 AWG XHHW-2 Cu: 0.33 inches OD, 0.129 lbs per ft, $1.78/ft I know which one I would pick under most circumstances. And insurance companies are just fine with the aluminum option.

dboreham 4y ago
USA could also transition to a proper mains voltage like much of the rest of the planet.
- chiph 4y ago
  230/240v does have it's advantages, primarily being able to use smaller diameter wire for the same current carrying capacity. But 50 Hz as a system frequency is just wrong. It results in oddities like running your railroad at 16-2/3 Hz.
  - eru 4y ago
    I'm not sure what's so odd about running your railroad at 50/3 Hz? Do you not like rational numbers? (I guess you are talking about three-phase power in general, or is there anything special about railroads?) In practice, just like everything in engineering, you don't run your grid at 50 Hz nor your railroad at 50/3 Hz. You run the grid at some frequency that varies slightly around 50Hz. There's always engineering tolerances. So even if you don't like rational numbers, it doesn't really matter whether you run the railroads at 50/3 +-0.01 Hz, or at 16.66 +-0.01 Hz. (I don't know how tight the tolerances are in practice here. It doesn't matter for the argument.)
    - lazide 4y ago
      Rational numbers are a lot more work than integers. Also, 60 is a common base for several things (degrees, time), which interact with the grid in numerous ways. It’s convenient to have them match.

oakwhiz 4y ago

Aluminum is a good choice for 0000 AWG and above.

freeqaz 4y ago

It also expands/contracts more than copper which can cause screws to come loose and trigger sparks that set fire to the inside of your walls. (Source: A home inspection report from a house I looked at buying a few years ago.)