Quick Answer / Summary: At 13.7 milliohms per metre, a 30 metre run of 16 AWG adds about 0.82 ohm to the circuit counting both conductors – over ten percent of an 8 ohm load and twenty percent of a 4 ohm load. That is the point where 14 AWG becomes the correct choice. For four short runs from the same coil, 16 AWG remains perfectly adequate.
A 100 foot coil of 16 gauge is the most common speaker cable purchase in the world, and most of it is cut into runs far shorter than the coil. The interesting question is what happens when one run uses the entire length.
The Full-Roll Calculation
Resistance accumulates over the outgoing and returning conductors, so a 30 metre run behaves like 60 metres of copper. At 13.7 milliohms per metre that is about 0.82 ohm. Into 8 ohms it costs roughly ten percent of the amplifier’s damping margin; into 4 ohms, twenty percent. Neither figure is catastrophic, and both are avoidable by stepping to 14 AWG for the long run and leaving the 16 for the short ones.
What Ten Percent Sounds Like
A ten percent damping reduction is not a tone control. It shows up as slightly less control in the bass and a marginally softer attack on transients – audible on demanding material in a good room, inaudible in a noisy one.
Cutting the Coil for Mixed Runs
Where one long and three short runs come from the same coil, cut the long run first and let the shorts take the remainder. Mixing gauges between channels is worse than mixing lengths, so keep all channels on the same gauge even if that means a second coil.
Buying a 100 ft Coil Sensibly
Coils are sold by length and gauge, and the two figures that matter are copper content and jacket rating. A 100 foot coil of 16/2 in a CL2 jacket suits in-wall work; the same length unrated belongs on the surface. Check the print rather than the listing photograph, because photographs are frequently of a different variant.
Copper Weight as a Check
Sixteen gauge two-conductor cable contains roughly 2.6 kg of copper per 30 metres. A coil that feels far lighter than that is likely copper-clad aluminium, which has about sixty percent of copper’s conductivity and behaves like a thinner gauge.
Storage and Oxidation
Copper oxidises at exposed ends. Keep the coil’s ends taped, store it dry, and re-strip before use if the copper has darkened. Oxidation is a termination problem, not a reason to discard the cable.
Splitting One Coil Across Channels
Where one coil serves four runs, keep the lengths within a metre of each other so channels behave alike. Unequal lengths shift high-frequency roll-off slightly, and the mismatch is easier to avoid than to correct after installation.
16 AWG Over Distance
| Run Length | Circuit Resistance | Verdict at 8 Ohm |
|---|---|---|
| 10 m | About 0.27 ohm | Adequate |
| 20 m | About 0.55 ohm | Acceptable |
| 30 m | About 0.82 ohm | Step to 14 AWG |
| 30 m at 4 ohm | About 0.82 ohm | Too high – use 12 |
| Four short runs | Under 0.3 ohm each | Adequate |
Practical Applications
Planning a long single run from a 100 foot coil, wiring several short runs from one purchase, checking copper content by weight, and deciding whether a long run needs a heavier gauge.
Frequently Asked Questions
Can I run 100 ft of 16 gauge speaker wire?
You can, but into 8 ohms it adds about 0.82 ohm to the circuit, which costs roughly ten percent of damping. For a single long run, 14 AWG is the better choice; for several short runs, the same coil is fine.
How much does 16 gauge resistance matter at 4 ohms?
It doubles in proportion: the same 0.82 ohm is about twenty percent of a 4-ohm load. That is the point at which 12 AWG becomes appropriate rather than optional.
How can I check a coil is really copper?
Weigh it: 16/2 copper runs about 2.6 kg per 30 metres. A much lighter coil is likely copper-clad aluminium, which conducts like a thinner gauge.