As noted in our blog on building our Philippine house /our-philippine-house-project-philippine-electrical-wiring/ we used stranded rather than solid electrical cable. We did this on the casual advice of our foreman and accepted the advice and bought and used stranded wire. At the time we did not realize that there are complications with the use of stranded wire. First of all, most outlet and switches are designed for use with solid wire. Stranded wire has a 15% larger diameter than equivalent solid wire. Most outlet and switch terminals are not large enough to accept the stranded wire or to securely connect it.
Shown below are a standard Panasonic outlet (L) and Anam Legend (R). The connectors are designed for the insulation to be stripped from the end of the solid wire which is then pushed into the small round terminal openings. There is no screw clamp to hold the wire and stranded 12 AWG (3.5mm) will not fit into the opening. Therefore, most standard electrical outlets could or should not be used with stranded wire. Of course we learned this only after buying the wire and many outlets and switches!
We experimented various ways of solving our problem.
We decided to try “tinning” the ends of our stranded wire before inserting them into the switch and outlet connectors. Tinning involves heating the wire ends with a soldering gun or iron until they are hot enough to apply solder which runs into the wire stands and cools to make a solid unit for insertion into the outlet or switch.
These tinned, stranded wires were much too big in diameter to fit into the standard outlet connectors. We found the Philippine-made Meiji outlets. As can be seen below they easily and securely clamped tinned #12 AWG and even #10AWG. (The 10AWG is really too high capacity for a standard wall outlet). The #12 wire is black and the #10 (5mm) is red. We found the Meiji outlets at Ace Hardware for P129.75. However we learned from our expert commenters that these screw terminals are inferior to the terminals using spring clips because screws terminals cannot adjust to expansion and contraction of the connection and loosen over time, whereas spring terminals maintain a constant, secure connection .
The Anam Legend switches we bought were useless with #12 stranded wire. Our electricians would take strands off the wire so they would fit into the Anam switch connectors. Probably this is not really a problem as out lighting circuits have a minimal load — but it bothered us.
So, as you can see, the initial selection of stranded rather than solid wire required that we shop for special outlets and switches which can accommodate the 3.5mm stranded wire. Finally we found that Panasonic makes a series of switches and outlets which are specifically made to accept stranded wire — the Panasonic Full Color Wide Series with “global terminals”. Most switches are specifically labeled for solid wire only. These Panasonic units are labeled for “rigid” wire. Basically this means that five or seven strand wire can be used. Further, they accommodate wires up to 4mm square. Since stranded wires are about 15% larger in diameter than solid wire, a 3.5mm stranded wire is actually 4mm. The stranded wire fits very well into the Panasonic units and is held very securely. The Panasonics are rated at 16A/250vac. Using these switches and outlets with 3.5mm stranded wire and 15A breakers makes a very satisfactory outcome, giving us the advantages of stranded wire — it’s easier to pull through conduit and may resist damage from flexing better than solid wire — together with outlets and switches designed for this wire. We write this so that other Philippine house builders may profit from our experiences.
As for us, we’ll probably slowly replace all out switches and outlets — not because it’s necessary, but because having things not quite right is slightly annoying.