Is Alloy Conductive?

[IOU0]

Just for you i checked between my swing arm bobbins and an engine bolt.
Guess what.......we have 0.00 on the meter.
Providing the ally you are connecting to is earthed to the chassis then not an issue as far as i can see!

[demographic]

Not wishing to be too much of a pedant but steel is an alloy of iron, carbon and various other elements depending on what properties are needed.

IIRC Aluminium is more electrically conductive than steel though.
In fact, Ive just searched and found this...


"In physics, the term “conductivity” has several meanings. For metals such as aluminum and steel, it generally refers to the transfer of either thermal or electrical energy, which tend to be closely correlated in metals, since the loosely-bound electrons found in metals conduct both heat and electricity.

Thermal Conductivity
Thermal conductivity, the ability of a material to conduct heat, is normally measured in watts per kelvin per meter. (“Watt” is a unit of power, typically defined either as volts times amps or joules of energy per second. The “kelvin” is an absolute unit of temperature, where zero kelvins is absolute zero). Materials with good thermal conductivity transmit large amounts of heat quickly, such as the fast-heating copper bottom of a cooking pot. Poor thermal conductors carry heat slowly, such an an oven mitt.

Electrical Conductivity
Electrical conductivity, the ability of a material to conduct current, is normally measured in siemens per meter. (“Siemens” is a unit of electrical conductance, defined as 1 divided by ohms, where an ohm is a standard unit of electrical resistance). Good electrical conductors are preferred for wiring and connecting. Poor conductors, called insulators, create a safe barrier between live electricity and the environment, such as the vinyl insulation on an extension cord.

Conductivity in Aluminum
Pure aluminum has a thermal conductivity of about 235 watts per kelvin per meter, and an electrical conductivity (at room temperature) of about 38 million siemens per meter. Aluminum alloys can have much lower conductivities, but rarely as low as iron or steel. Heat sinks for electronic parts are made of aluminum due to the metal's good thermal conductivity.

Conductivity in Carbon Steel
Carbon steel has a much lower conductivity than aluminum: a thermal conductivity of about 45 watts per kelvin per meter, and an electrical conductivity (at room temperature) of about 6 million siemens per meter.

Conductivity in Stainless Steel
Stainless steel has a much lower conductivity than carbon steel: a thermal conductivity of about 15 watts per kelvin per meter, and an electrical conductivity (at room temperature) of about 1.4 million siemens per meter."

[JackyJoll]

Why use chassis return and not a common return lead?

Your future electrical faults are likely to be in the chassis connections.

[Screwdriver]

Beware galvanic corrosion between steel/aluminium interfaces, especially if you are also going to pass a current through that interface.

[Screwdriver]

I’d keep the aluminium isolated from any electrical connection and away from any steel fastener if I were you. Use plastic collars/washers etc.

[moth]

Underground mains cables have aluminium conductors nowadays. Cheaper, see?

Off the top of my head, copper has a conductivity of ~(55 S/m)*10^6, and aluminium ~(36 S/m)*10^6.

If you're feeling flush, silver is a better conductor than copper

[Mr. Dazzle]

Underground mains cables have aluminium conductors nowadays. Cheaper, see?

Off the top of my head, copper has a conductivity of ~(55 S/m)*10^6, and aluminium ~(36 S/m)*10^6.

If you're feeling flush, silver is a better conductor than copper

Overhead cables are aluminium too AFAIK. Lighter, see?

There's also a drive to make the windings in electric motors from Aluminium too, again 'cause it's lighter (and also cheaper, easier to work, easier to recycle etc.). Sure you need fatter wires becuase it's less conductive than copper but it's also less dense. The conductivity/density ratio is better for Aluminium.

It's 65% as conductive as copper but only 30% of the density...

So yes, Alu is conductive.

[moth]

Overhead cables are aluminium too AFAIK. Lighter, see?

Some are AAAC, some are ACSR, some are ACCC. Depends on weight, operating temperatures and span.

[Mr. Dazzle]

Overhead cables are aluminium too AFAIK. Lighter, see?

Some are AAAC, some are ACSR, some are ACCC. Depends on weight, operating temperatures and span.

What's the R stand for? Reinforced?

I'm guessing AAAC is "Alu, Alu, Alu, Copper"? Working from the OD of the cable inwards etc.

1888 - my general rule is; if it's important to ground things properly (and I would suggest anything involved with charging batteries ranks as 'important'!) then you want a dedicated cable for it.

[moth]

Overhead cables are aluminium too AFAIK. Lighter, see?

Some are AAAC, some are ACSR, some are ACCC. Depends on weight, operating temperatures and span.

What's the R stand for? Reinforced?

I'm guessing AAAC is "Alu, Alu, Alu, Copper"? Working from the OD of the cable inwards etc.

All aluminium alloy conductor - what it says
Aluminium conductor, steel reinforced - steel wire core
Aluminium conductor, composite core - carbon/glass fibre core

There's ABC as well, if you like to take a punt

[Mr. Dazzle]

See I'd have guessed the conductor was the inside because i'm still thinking in terms of insulated wires - but I suppose when you're talking HVAC it makes sense to have the conductors on the outside for inductive losses and because it's easier to make connections? It also means you can wrap lots of conductors around a common structural centre core.

Not a clue with ABC, I'd have to google.

[moth]

See I'd have guessed the conductor was the inside because i'm still thinking in terms of insulated wires - but I suppose when you're talking HVAC it makes sense to have the conductors on the outside for inductive losses and because it's easier to make connections? It also means you can wrap lots of conductors around a common structural centre core.

Not a clue with ABC, I'd have to google.

Don't forget skin effect.

Transmission voltages are DC.

To save you Googling, ABC is aerial bundled cable - 4 insulated conductors bundled together.

[Mr. Dazzle]

Yeah that's what I meant by 'inductive' losses - even though I know inductive losses are usually referring to something else! I am currently getting involved with skin effect etc. via electric motors. Even though they're DC motors they have AC 'effects' because they spin fast and hence all the winding are subjected to an alternating current as the permanent magnets whizz past going N-S-N-S-N-S-N-S really quickly.

[MingtheMerciless]

Telecoms wiring is usually copper, there was a brief dalliance with ally in the 70's and 80's but we are reaping the reward for that now with the aluminium going brittle and fracturing if you so much as look at it, whereas some of the copper put in during the 60's is still going strong. Ally earth tape is being put into some sites to deter earthing theft as you get much less for ally than copper and it weighs a lot less.

On the railway we had a few areas using ally conductor rail as its lower resistance than steel con-rail allowed the substations to be spaced further apart but we had issues with the stainless steel contact head de-bonding from the aluminium and also as the rail is lighter we had creep issues where every time time the pickup shoe on the train hit the leading edge ramp of the con-rail it would nudge it ever so slightly in the direction of travel which over time lead to the conductor rail cables linking the con-rails getting stretched to breaking point. It was also very expensive. So it's all been ripped out as far as I know and we are back to steel con-rail.

Due to skin effect some RF feeder cables have a hollow core and the outer edge of the central conductor is coated in rhodium and other expensive metals to decrease cable losses.

[JackyJoll]

Well, that lot should see 1888 on his way.