Electrical – Is a multi-strand conductor better suited for house-hold wiring than a single-core

electricalwiring

Back-ground:

The wiring at the residence dates back a century – almost. The old wires were wound in cloth, and are pretty thick aluminium/tin-coated copper. The old energy meter (one with a marked wheel that rotates; mfr. Contimeter) was recently replaced with one of these new-fangled electronic digital ones. My electric load is unchanged. Yet the new meter appears to register easily double the old one.

Body:

Typical appliances that form the electric load are as follows –

  • Ceiling Fans
  • Lamps (Incandescent, Fluorescent, and Compact Fluorescent)
  • Television (old-fashioned CRT type)
  • Computer (with a similarly old-fashioned CRT monitor)
  • Micro-wave oven
  • Vacuum cleaner

The electrician says the old wiring should be replaced by newer 2.5 sq.mm wires; I believe this used to be called a 5/22 wire. He further recommends a multi-strand wire rather than one with a single core. What little I recall is that a multi-strand conductor is suited for HF/VHF and such applications. The supply line from the utility company is 240V@50cps.

Question:

Is a multi-strand conductor better suited for house-hold wiring than a single-core?

Best Answer

Stranded

Flexibility

Stranded wire is more flexible than solid core wire, which makes it well suited in situations where there will be movement of the wire. It also makes routing the wire through a building a bit easier.

Higher resistance to metal fatigue

Where solid core wire will weaken and break, stranded wire holds up to being bent repeatedly.

Solid

Cheaper to manufacture

While this savings may or may not be passed on to the consumer, solid core wire is cheaper to make.

More rugged

Solid wire resists cutting and stretching damage better than stranded wire.

Lower resistance

Given a solid and stranded wire of the same diameter, the solid wire will have a lower resistance. This is because there will always be gaps between the strands of a stranded wire. A stranded wire of the same gauge, will have a larger diameter than a solid wire to compensate for this. When you buy wire, you'll always buy it based on gauge. Both solid and stranded wires will have the same resistance, the stranded will simply be a bit larger in diameter.

Easier to terminate

If you're not careful when stripping stranded wire, you can end up cutting off strands (usually only a problem with smaller gauge wire, or wire with lots of strands). Depending on the number of removed strands, the ampacity of the wire can be negatively affected. Though nicking a solid core wire while stripping can make the wire more susceptible to breakage, so this isn't a clear cut advantage.

Solid core wire can be used in push in ("backstab") terminals, more often than stranded. This can be a pro or a con, depending on who you talk to.

Stranded wire can be more difficult to terminate on screw terminals, as you can sometimes have escapee strands which don't end up under the screw. This again can affect the ampacity of the wire.

Because stranded wire has a larger diameter, it tends to fill up twist-on wire connectors faster (less wires allowed in the connector).

Unless there's a lot of movement within the home (RV, house boat, frequent earthquakes), or you're pulling the wire through conduit. I'd say there isn't much of a difference either way.

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