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I am not an electricity/wiring guy so maybe you can help me understand. I thought aluminum is dangerous to wire with because it is a fire hazard (I bought a hom

I am not an electricity/wiring guy so maybe you can help me understand. I thought aluminum is dangerous to wire with because it is a fire hazard (I bought a home this year and this was a prominent warning in my reading). Is that because it needs to be done very carefully? I imagine most data centers would not mess with a fire risk on such a scale.

deleted 9mo ago
[deleted]
MSFT_Edging 9mo ago
Old aluminum wiring in your walls with cloth insulators, designed for a time where electricity consumption was a small fraction of today's electrified usage is dangerous because you're overloading an old, unprepared system. Aluminum bus bars(solid, often exposed) would be designed for the required power levels and installation criteria.
- Aurornis 9mo ago
  Aluminum home wiring was from the 60s and 70s. It’s not the same as cloth covered knob and tube from earlier years. It has its own problems, but I’d take a house with knob and tube over a house with aluminum wiring.
- margalabargala 9mo ago
  Household electrical usage has decreased, not increased, since that time. Your scaling is backwards. Old aluminum wires in your walls were designed for a time when you lit your home with 100 watt incandescent lamps rather than 12 watt LEDs.
  - quesera 9mo ago
    Only true for lighting circuits though, and most household circuits are mixed. The quantity and (edit: aggregate) power draw of modern appliances is far greater now than 60 years ago, so the overall load on the old wires is much higher.
    - Jblx2 9mo ago
      > power draw of modern appliances Here's a article that claims that refrigerator energy efficiency has improved dramatically from 1972 to 2012. https://appliance-standards.org/blog/how-your-refrigerator-has-kept-its-cool-over-40-years-efficiency-improvements https://appliance-standards.org/blog/how-your-refrigerator-h... I'd bet that modern TVs are more efficient that CRT televisions. Do most people even have desktop computers anymore, or have they mostly been replaced by laptops, tables, and phones? I'd be interested to see the efficiency numbers for electric clothes dryers over time. I wouldn't be surprised if they are also slightly more efficient than older models, even if they are still using resistance heating. Due to smarter electronics that automatically turn the unit off after the clothes are dry (air humidity sensor). I think electric ranges, dish washers, toasters and coffee machines have been ubiquitous since the 1960s (but are probably about the same energy-consumption wise). Air conditioning units are one thing that I'd believe are much more common today than in the 1970s and 1980s. Household sizes are also smaller, so less electricity used for electric water heaters, and the oven, etc.. Electric vehicles are an up and coming user of electricity. What other appliances are likely to be using more now than before?
      - quesera 9mo ago
        These are good points, but having worked on a few older houses, I usually see overextended and overloaded circuits, not the opposite. Standard small-house service used to be 60A, sometimes as few as 4 circuits! It's now 100A minimum by code, with 200A common. Ovens/ranges have gone from 30A to 50A (dedicated) circuits by code. Microwaves also require dedicated circuits now. Gaming computers with big GPUs are common. Air fryers and electric pressure cookers are newly-common countertop appliances. People definitely use resistive electric space heaters more now (very cheap, much safer than the older options). And there's a trend away from gas and to electric ranges and water heaters. Heat pumps are also increasingly common. You mentioned air conditioners and EV chargers. Kitchens and bathrooms are now required to have dedicated (and GFCI) circuits. Household sizes are smaller, but houses are larger. So I guess I'd say that, properly expanded, individual circuits should carry less current than they used to. But very often, appliances (AC, microwave, gaming rig, air fryers), are just "plugged in" to an unexpanded system, with varying results. If you're lucky, they pop a breaker and you call an electrician. If you're not lucky, they push the power draw into uncomfortable zones, esp for Al wire.
Analemma_ 9mo ago
It’s a fire hazard in residential houses where people frequently do their own wiring, because it needs more expertise to wire correctly. Copper wiring is a lot more forgiving to being hooked up by amateurs. The biggest reason is that aluminum oxidizes, and unlike copper, the oxide layer has high resistivity. In theory that shouldn’t be an issue in datacenters hiring expert technicians.
- pixl97 9mo ago
  Yea, in a data center setup the cost difference can justify the things like soldiering connections rather than mechanical connectors with a higher resistance.
u8080 9mo ago
Aluminum wires became brittle over time(tens of years), fluid which requires some maintenance for screw terminals and inducts galvanic corrosion when coupled with copper without special care. If wiring was properly done and maintained, it is okayish.
auxym 9mo ago
It's because aluminium has a higher coefficient of thermal expansion. It expands and shrinks more as it heats, and as those cycles add up it tends to loosen electrical connections. Loose connections have higher resistance, heat up and can cause fires. That said, there is no reason we can't design better connectors that can withstand the expansion and shrinkage cycles, like spring loaded or spring cage connectors.
- quickthrowman 9mo ago
  Wiring devices have almost all been universally rated for Al/Cu conductors for the last 50 years, what you’re talking about only lasted a handful of years in the early 1970s. Go look at the terminals on any light switch or receptacle at Home Depot, they’re all Al/Cu rated.
_heimdall 9mo ago
Unless I'm mistaken, the risk with aluminum is that it can expand and contract if it gets too hot. Aluminum sized properly with the correct connectors torqued to spec would be fine, aluminum wires in a residence with a DIYer working on it can be riskier and is why inspectors will always note it.
crote 9mo ago
That's the "a pain to work with" part. Residential aluminum is a Really Bad Idea because DIY Dave will inevitably do something wrong - which then leads to a fire hazard. Copper is a lot more forgiving. But a large scale datacenter, solar farm, or battery storage installation? Those will be installed and maintained by trained electricians, which means they actually know what a "torque wrench" is, and how to deal with scary words like "corrosion" and "oxidation". Like I said: it's what's used for most of the power grid. With the right training it really isn't a big deal.
scherlock 9mo ago
Aluminum oxide has high resistance and if you mix aluminum wiring with copper outlets, etc the impedance mismatched is what causes fires. You need to either have special copper pigtails installed or use fixtures that are rated for aluminum wiring. For commercial installs, it shouldn't be a problem as long as it's planned for.
knollimar 9mo ago
Old aluminum is dangerous. Modern aa-8000 series aluminum is fine. Bigger pipes though.
jabl 9mo ago
Aluminum got a bad rep due to a lot of poor installations made in the 1960 and 70'ies. Subsequently new alloys (AA-8000 series) for wiring, new installation and termination procedures etc. have been developed, and AFAIU the situation today is much better. It's still trickier than copper wiring, so probably not a good option for DIY, but for some industrial installation with competent personnel and where the savings can be substantial it could certainly be an attractive option. https://en.wikipedia.org/wiki/Aluminum_building_wiring https://en.wikipedia.org/wiki/Aluminum_building_wiring
quickthrowman 9mo ago
If you apply antioxidant paste, torque the terminations to the correct value, and use wiring devices rated for Cu and Al conductors, there are zero problems. Most homeowners know none of the requirements of aluminum wire installation so I don’t recommend using it, oxidation is bad and can cause fires. Just pay for copper NM cable, it’s dirt cheap anyways. FWIW I sell and run electrical work for a living. I assume crote and amluto work in the electrical industry, since they’re the only other posters in this discussion who know what they’re talking about.

deleted 9mo ago

[deleted]

MSFT_Edging 9mo ago

Old aluminum wiring in your walls with cloth insulators, designed for a time where electricity consumption was a small fraction of today's electrified usage is dangerous because you're overloading an old, unprepared system. Aluminum bus bars(solid, often exposed) would be designed for the required power levels and installation criteria.

Aurornis 9mo ago
Aluminum home wiring was from the 60s and 70s. It’s not the same as cloth covered knob and tube from earlier years. It has its own problems, but I’d take a house with knob and tube over a house with aluminum wiring.
margalabargala 9mo ago
Household electrical usage has decreased, not increased, since that time. Your scaling is backwards. Old aluminum wires in your walls were designed for a time when you lit your home with 100 watt incandescent lamps rather than 12 watt LEDs.
- quesera 9mo ago
  Only true for lighting circuits though, and most household circuits are mixed. The quantity and (edit: aggregate) power draw of modern appliances is far greater now than 60 years ago, so the overall load on the old wires is much higher.
  - Jblx2 9mo ago
    > power draw of modern appliances Here's a article that claims that refrigerator energy efficiency has improved dramatically from 1972 to 2012. https://appliance-standards.org/blog/how-your-refrigerator-has-kept-its-cool-over-40-years-efficiency-improvements https://appliance-standards.org/blog/how-your-refrigerator-h... I'd bet that modern TVs are more efficient that CRT televisions. Do most people even have desktop computers anymore, or have they mostly been replaced by laptops, tables, and phones? I'd be interested to see the efficiency numbers for electric clothes dryers over time. I wouldn't be surprised if they are also slightly more efficient than older models, even if they are still using resistance heating. Due to smarter electronics that automatically turn the unit off after the clothes are dry (air humidity sensor). I think electric ranges, dish washers, toasters and coffee machines have been ubiquitous since the 1960s (but are probably about the same energy-consumption wise). Air conditioning units are one thing that I'd believe are much more common today than in the 1970s and 1980s. Household sizes are also smaller, so less electricity used for electric water heaters, and the oven, etc.. Electric vehicles are an up and coming user of electricity. What other appliances are likely to be using more now than before?
    - quesera 9mo ago
      These are good points, but having worked on a few older houses, I usually see overextended and overloaded circuits, not the opposite. Standard small-house service used to be 60A, sometimes as few as 4 circuits! It's now 100A minimum by code, with 200A common. Ovens/ranges have gone from 30A to 50A (dedicated) circuits by code. Microwaves also require dedicated circuits now. Gaming computers with big GPUs are common. Air fryers and electric pressure cookers are newly-common countertop appliances. People definitely use resistive electric space heaters more now (very cheap, much safer than the older options). And there's a trend away from gas and to electric ranges and water heaters. Heat pumps are also increasingly common. You mentioned air conditioners and EV chargers. Kitchens and bathrooms are now required to have dedicated (and GFCI) circuits. Household sizes are smaller, but houses are larger. So I guess I'd say that, properly expanded, individual circuits should carry less current than they used to. But very often, appliances (AC, microwave, gaming rig, air fryers), are just "plugged in" to an unexpanded system, with varying results. If you're lucky, they pop a breaker and you call an electrician. If you're not lucky, they push the power draw into uncomfortable zones, esp for Al wire.

Analemma_ 9mo ago

It’s a fire hazard in residential houses where people frequently do their own wiring, because it needs more expertise to wire correctly. Copper wiring is a lot more forgiving to being hooked up by amateurs. The biggest reason is that aluminum oxidizes, and unlike copper, the oxide layer has high resistivity. In theory that shouldn’t be an issue in datacenters hiring expert technicians.

pixl97 9mo ago
Yea, in a data center setup the cost difference can justify the things like soldiering connections rather than mechanical connectors with a higher resistance.

u8080 9mo ago

Aluminum wires became brittle over time(tens of years), fluid which requires some maintenance for screw terminals and inducts galvanic corrosion when coupled with copper without special care. If wiring was properly done and maintained, it is okayish.

auxym 9mo ago

It's because aluminium has a higher coefficient of thermal expansion. It expands and shrinks more as it heats, and as those cycles add up it tends to loosen electrical connections. Loose connections have higher resistance, heat up and can cause fires. That said, there is no reason we can't design better connectors that can withstand the expansion and shrinkage cycles, like spring loaded or spring cage connectors.

quickthrowman 9mo ago
Wiring devices have almost all been universally rated for Al/Cu conductors for the last 50 years, what you’re talking about only lasted a handful of years in the early 1970s. Go look at the terminals on any light switch or receptacle at Home Depot, they’re all Al/Cu rated.

_heimdall 9mo ago

Unless I'm mistaken, the risk with aluminum is that it can expand and contract if it gets too hot. Aluminum sized properly with the correct connectors torqued to spec would be fine, aluminum wires in a residence with a DIYer working on it can be riskier and is why inspectors will always note it.

crote 9mo ago

That's the "a pain to work with" part. Residential aluminum is a Really Bad Idea because DIY Dave will inevitably do something wrong - which then leads to a fire hazard. Copper is a lot more forgiving. But a large scale datacenter, solar farm, or battery storage installation? Those will be installed and maintained by trained electricians, which means they actually know what a "torque wrench" is, and how to deal with scary words like "corrosion" and "oxidation". Like I said: it's what's used for most of the power grid. With the right training it really isn't a big deal.

scherlock 9mo ago

Aluminum oxide has high resistance and if you mix aluminum wiring with copper outlets, etc the impedance mismatched is what causes fires. You need to either have special copper pigtails installed or use fixtures that are rated for aluminum wiring. For commercial installs, it shouldn't be a problem as long as it's planned for.

knollimar 9mo ago

Old aluminum is dangerous. Modern aa-8000 series aluminum is fine. Bigger pipes though.

jabl 9mo ago

Aluminum got a bad rep due to a lot of poor installations made in the 1960 and 70'ies. Subsequently new alloys (AA-8000 series) for wiring, new installation and termination procedures etc. have been developed, and AFAIU the situation today is much better. It's still trickier than copper wiring, so probably not a good option for DIY, but for some industrial installation with competent personnel and where the savings can be substantial it could certainly be an attractive option. https://en.wikipedia.org/wiki/Aluminum_building_wiring https://en.wikipedia.org/wiki/Aluminum_building_wiring

quickthrowman 9mo ago

If you apply antioxidant paste, torque the terminations to the correct value, and use wiring devices rated for Cu and Al conductors, there are zero problems. Most homeowners know none of the requirements of aluminum wire installation so I don’t recommend using it, oxidation is bad and can cause fires. Just pay for copper NM cable, it’s dirt cheap anyways. FWIW I sell and run electrical work for a living. I assume crote and amluto work in the electrical industry, since they’re the only other posters in this discussion who know what they’re talking about.