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.
Panasonic outlet
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.
Tinned 12 AWG stranded wire
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 .
Meiji Electrical Outlet
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.
July 25, 2012 at 6:11 pm
Why was not pigtailing solid wire to the stranded wire not an option?
July 28, 2012 at 4:04 pm
DT,
I did experiment with pig tailing. There was just not enough spare room in the boxes to allow it. The Panasonic switches and outlets made for stranded wire was the best solution.
Bob
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May 29, 2011 at 9:41 am
The spring type connector is very convenient for small items such as lights that are low power consumers.
BUT look at the actual connecting metal part, it is a flat surface onto a round wire, hardly much area for current to flow past. Sold or stranded wire will make no difference to this unless a crimp terminal is applied to the cable one with a flat ending?
A screw terminal into stranded wire would be my choice since there is more metal contact across the join. The screw pushes its way into the strands and compresses these against the sides of the connector.
Loose contacts add resistance to the connection which compounds the problem and leads to fire. An annual inspection is not beyond most home owners, cut the mains and feel the connecting blocks or go over the screws with a screwdriver.
Another important point of siting each electrical connection box within easy access.
I was always taught when soldering to make the physical connection strong before applying the solder.
May 27, 2011 at 5:57 pm
John Thede Joergensen to me
– Hi Bob.
I tried to find the current values for the 6mm2 Alu wire but i cant. We never use less than 16 mm2 Alu, but that has a current value at 48 Amp under normal heat transfer, and 41 Amp under bad conditions, (Above 30 DG C), which it can be in your case, despite its outdoor and free air.
But these figures give an impression of the nominated capacity of cables. And interpolating on 16mm2 to 6 mm2 gives app. 16 Amp Maximum.
That is in my world too little, and im sure your AC and total consumption will bring the load ability to the limit. Another thing is then, if the load are simultaneous or not.
I know its another matter here with electric stoves and lots of electric machinery, but minimum to a 1 family house is 4x10mm2 CU, or 4x16mm2 Al. And that is 3 phases and neutral, so load on 3 wires.
I guess that the total installation from thew transformer to the consumers are equally under dimensioned, but you are not paying it directly, as it is loss of energy, which the supplier normally pays. When that is said, its only the consumers that pays as the companies need to invoice their expenses.
Yeaa, so your human protection is a direct null, or earth, and all fault current must be led to the earth connection, and back to the transformer. Here its calling nulling.
If the soil dries out, or your earth connection is not in stable wet soil, you risk over voltage on the surface of all machinery that is earth connected.
Do you know fault current relays. ??
Ha ha we all need to learn all the life, but honestly there isn’t much to say about this. Its technical stuff, and i have seen so many bad samples on material that should never have been produced, nor accepted as electrical material.
Your right, the Panasonic seem to be professional gear.
NO worry Bob.
Regards to you and your Wife.
John
May 27, 2011 at 5:55 pm
Hi John,
The pole to house service wire is 6 AWG aluminum. It seems a bit small so maybe I am paying to heat the Philippines when both aircons are running! This “duplex” cable consists of a single insulated stranded aluminum load wire and a bare aluminum ground wire which also serves to support the cable.
Yes, it’s the single wire earth return system. Each pole has a ground rod. The panel box ground is to copper clamps on the rebar in the foundation.
The breakers I am using are GE plug-in types made in Singapore. The specs include 40C, type TQL 2420X. I wonder if I should not have used bolt-in breakers instead. They seem more secure.
Since our last exchange, I have learned that Panasonic (formerly National) makes just the right outlets and switches for use with 3.5mm2 stranded copper wire. They make “Wide Series” switches and outlets which are rated for “rigid” copper wire up to 4.0mm2, including both solid and stranded wire, as long as it’s rigid — i.e. five or seven strand.
Since stranded wire is about 15% larger in diameter than equivalent solid wire, the 4.0mm2 specification perfectly accommodates 3.5mm2 stranded wire and in fact the wire fits in perfectly and is very securely locked in. There are no screws, just the push in spring clamp. They are rated for 16A at 250v. I’m guessing that using these Panasonic units with 3.5mm2 stranded and a 15A breaker will make a very safe job.
I could have saved both of us some unnecessary cogitation if I had done my product research before buying the wrong switches and outlets!
Maybe someone will learn from my misadventure.
Best regards,
Bob
May 27, 2011 at 5:55 pm
Hi Bob.
Unfortunately its not only on the low voltage side of the transformer that
conflict with the short circuit capacity of the supply system, but the fact,
that there is a transformer close, and the magnetic circuit on that is able to
deliver a substantial energy to the short circuit, must be adequate.
Im always in doubt which measure you use for wire, is 6# equal 6 square mm??
If so, a 6 mm2 alu is in my world a bit under dimensioned, just taking into consideration
what load i know of you have, but its a guess based on practice, not knowledge.
Alu have a substantial lower current leading rate than copper and must be reduced.
How long is that alu cable then ??
Im not familiar with the meaning of the SWER system. ?? We use terms as TNT, TNC, and etc.
But i cant imagine that the ground shall be leading full current return to the transformer. ?? !!
The ground can be used to lead fault current back, but its seldomly enough to secure safety,
but must be combined with a current fault relay.
OKAY, SWER = Single Wire Earth Return system. ??
Is it so, that you have only 1- ONE single wire into the house, and then all the current consumption
must pass back to the transformer through the soil. ???
Gosh, of that is correct im chocked, because you use lots of energy, high current flow,
and you earth electrode can dry out, so you have high loop resistance from the transformer.
So then your short circuit current available will variate with the effiency of the earth electrode
in your house, as well as the corresponding electrode near the transformer.
A well functioning circuit breaker trips if the current reach 20% above the stamped value.
This happens if you have a short circuit, OR, when the consumption is too high.
Remember, if the voltage drops down, the current raise, so a voltage drop can actually lead to
a too high current and a cut out of the breaker.
A 20 amp breaker will protect a 3,5 mm2 wire, even in higher temperatures than basic.
But it will not protect a 16 amp socket outlet, which will heat and burn if overloaded long time.
Before you throw them, then take a look at the cut out characteristics of the breakers you use.
I dont know the origin, nor the electrical materials spec they are produced under so i cant tell you
how they are marked. It can be with a letter, or it can be with symbols.
The cable underground might be harmed, but its easy to find that kind of fault. Even a ohm meter can do that
if its really serious. disconnect the cables going there in the supply end, (both or all wires in the cable).
Measure the resistance between each wire, and to a safe ground point, and the resistance must show
infinite, or more than 5 Mega ohm. If the fault is minor, or changing, it is needed to use a “Megger”.
A Ohm meter, that send out 500 Volt, and can measure high resistance circuits, and then the measurement
must be more than 5 M Ohm. A commercial ohm meter use max 9 volt, and that is far from sufficient to
burn through a fault with a relative high impedance, such as moisture, that dries out now and then.
A design capacity of 80% sound to me to be a good safe load limit.
In the end, its the material, such as switches that isn’t physical dimensioned to take
the thicker wires needed if its used correct to the temperature reduction. Its a known problem,
and i haven’t heard about manufacturers that delivered material that was suitable for
higher temperatures. We had huge problems connecting cables into motors. imagine a 350 KW
compressor, in a Y/D start, cable glands, and the connection box is just dimensioned to the cable
that match under normal conditions, but one step higher cables, cant go into the standard box,
so often its was necessary to build bigger boxes, using welders and steel plate to do so.
So your suggestion to make the hole a bit larger to take 3,5 is the way, and the only way,
unless you can find material that is over dimensioned and can take larger wires.
Often its good practice and sense that is used in such cases.
John
May 27, 2011 at 5:52 pm
Hi bob.
Thanks, i’v got the photo and my virus scan didnt kill it this time.
Electric installation is my main knowledge area.
Out of your writings i see one big and well known problem that can cause problem in future.
At a certain point, the supply net can deliver a certain current with a specific
resistance in the net from the power supplier, to the end user.
Small diesel generators can hardly give 3 time the stamped value, sp they need to be big to assure that
smaller breakers work, but if just one user is at the value of the generator, you need to use very special
breakers to secure the generator.
Your 20amp breaker should clearly have cut out the short circuit, but didn’t,
because the electric supply net is too weak and to stretched to deliver the needed
current to trip the breaker. In weak net, like the Philippines, this is a common known problem.
You can also see this in “brown outs”, where the voltage falls and light get red and dark.
The supplier cant keep up voltage, when demand grows.
This is actually the worst that can happen to a system like yours, too large circuit breakers,
and a too low supply ability, called, “the close loop resistance is too high”.
Normal is, that the short circuit need 10 – 12 time the current stamped on the breaker, to cut out the
breaker safely. If the installation cant lead that current, it wont trip ever.
Therefor its very wise never to install more than needed, even if a 20amp breaker should trip
in any other place as Philippines, i would find 16 amp breaker for 16 amp outlet,
and 10amp for 10amp outlet, and so on. maybe even split the light systems into 6amp breakers
if possible. I know your house inst that inflammable, but its such things like this,
that causes most electric ignited fires.
Next problem is, that the load capacity of a specific wire is based on the cooling capacity where its
placed, so 1,5mm2 max load 13,4amp, is based on max 70dgc in the copper,
and a surrounding temperature not over 30 dgc. When its in hot countries, its needed to step one
wire sice up, and test the load capabilities under the conditions where its used.
(Tables with reduction factors), or even take into consideration that the load must be kept lower
than the stamped values on the outlets.
Take an electric motor, stamped 300 KW, as we often use for large chillers, but a 300 KW motor in
Saudi Arabia, can not be loaded with 300 kw, as it will get too hot, so often its needed to go one step up in motor,
or secure that the compressor is never loaded higher as the maximum load capability of the motor.
Again i need to mention Ohm’s law. Voltage x current = Watt. 240×10=24000 watt, or 2,4KW
Take a unit that take 2,4 kw. connected to 240 Volt, is 10 amp only, but connect it to 120 volt,
now it use 20 amp. In US, the voltage is 110 or 120, and the material you buy there is therefor
for this only, and you never get the wrong material.
If you buy your material in US, and bring it to Philippines, you just need to asure that the US
material is tested to be used on 240 volt, where it is normally used on 110 only. Especially this can be VERY
important as the humidity in Phil often is very high, and if the isolation barriers is too low,
it will create a arc, ignite and burn the isolation material away.
Using larger dimension wires is never an overkill, but using too large circuit breakers is a kill.
Using soclet outlets in the kitchen, its even better to have each outlet on its own but fitting
breaker, so make each of them 10amp, 16amp, or even 30amp,
but dont expect the breaker to be able to cut off the short circuit current if its larger breakers.
Circuit breakers can be bought with different cut off characteristics. You might need to find
special breakers for the 16 amp and up, tp be sure your short circuit protected in all cases.
Typical you can get quick, medium, and slow cut out char. here they are labeled with letters,
like C, G, And other, you might need to ask around to find how this is in Phil.
I am honestly a bit worried about the 20amp breaker that wouldn’t cut off.
That is a bad sign of a far too high loop impedance. The electric system cant deliver the
needed effect to cut off the breaker. Its weak.
Breakers is solely there to protect the installation, and not people primarily.
People protection is secondary, ignition, fire hazard, and etc.
People protection is take care of with fault circuit breakers, we call them HFI relays,
but what they do is, measure how much current goes into your house and return again
through the relay. if Max 40 Milli ampere is missing, its going to the ground somewhere
in a faulty spot, and the relay cuts off emediately.
200 amp is a lot. Equals 200×240=48000watt, or 48Kw,
i think you will never use that much in the same moment at any time.
I hope this gave just a little more “light” over the electricity issue.
Greatings from John
May 27, 2011 at 5:50 pm
John,
Thanks for your insights and recommendations. Our wire has seven strands. I looked carefully at the collection of switches and outlets I have. The Anam outlets I have are labelled for 10amps 1.6mm wire. No wonder they would not work with 3.5mm stranded! The Anam switches are 16amp for 2.0mm wire. I have a lot to learn. When shopping for regular outlets in the U.S. you generally don’t have to concern yourself with the capacity as 12AWG (3.5mm) solid wire is very standard.
I decided to use 3.5mm wire in our Philippine house because that’s what is standard in the U.S. It’s also what my Philippine electrical engineer specified, except in the kitchen where he specified 5.0mm wire. He also specified a 200amp panel. All this might have been overkill. 2.0mm wire would probably been fine except for air con circuits, less expensive and much easier to use. I just lost sight of the greater capacity of the 240v circuits in the Philippines than the 115v circuits in the U.S. This was brought home to me when I switched on a device with a short on a 16amp Royu outlet served by 3.5mm wire and a 20amp breaker. The outlet was destroyed and the breaker did not trip. It’s easy to see that the breakers are intended to protect the wiring, not the human being!
I’ve resent the missing photo.
Thanks again!
Bob
May 27, 2011 at 5:48 pm
More exchanges on stranded v. solid wire:
Hello Dave Star.
Stranded wire is NOT a potential problem at all. So please dont worry. Its so, that smaller dimensions it dont matter a lot if its a solid wire, mean 1,5, 2,5, 4 mm2 SQRmm. But then it starts to matter. The case is, that the current tend to flow in the surface of the copper wire, this because of magnetic reasons. So this will reduce the real properties of current leading, so instead its needed to use stranded wire. If you use the correct connection Technic, its not a problem to connect to any connector, just the connector is made for the dimension of the wire. Using a stranded wire in a direct screw connector without any protection, such as a pin, will lead to the copper floating over time, mas most people tend to use far too much power in the screwdriver. The spring supported connector always have the correct tension – pressure, even when the wire gets hot, and expands, and later crimp again. The screw do NOT follow the wire back again, but leave a small gap, and less tension on the connection.
The solution, cutting 1 strand or 2, is ok, as long as the reduced area is sufficient to lead the current in that place.
Greating from
John
and…
Hi Bob.
Thanks.
I guess the entrance hole is dimensioned to the load the contact can take.
A copper wire is dimensioned to take a certain load continuously without overheating.
(PVC isolation, maximum heat 70 Dgc continuous)
An 1,5 mm2 copper can load 13,4 amp.
An 2,5 mm2 can take a load of 20 amp.
Most socket outlet are 6 amp, or 10 amp.
So if they can accept more than 1,5 mm2,
the risk that they are connected to
a fuse or circuit breaker more than 10 amp is big.
My gues is, that your socket outlet is 16 amp, equavilent to
app. 2,0 mm2, a size we dont know here.
Another reason might be that the manufacturer want to
have a smallest possible gap between the wire isolation, and the
isolation on the material, and thereby secure that harming material
dont enters the sensitive contact elements inside.
The spring connector has a exact tightening torque,
and will always keep the same torque. We have used them
in installations here for over 30 years, and the faults
on the connectors is a lot lower than screw terminals.
Its absolutely the best solution for single or multi8 stranded wire.
Just notice that stranded wire must be of the type with 5 or 7 cores,
and not the multi core type, or even high flex wire.
They must be used with pins.
I would enlarge the hole to fit. Just be careful not to harm the connector.
I wouldn’t tin the wire, its better it can find the right place and connection of it self,
letting each stranded wire find the best possible place in the bundle.
The transitional resistance will then be lowest possible, and over heating avoided
in the best possible way. i would even let the individual strand be sole, and not twisted.
The wires will then flatten out, but that is the best,
so it rest against the normal flat terminal surface.
Sorry, i didnt receive any photo, but im not in doubt about what we talk about.
Hope this is of help for you.
Greatings from John
May 14, 2011 at 7:22 pm
Hi Bob.
Tinned soldering of stranded wire is ok, but in most cases not needed. Tin is even softer than copper, so it wont help on the “material creeping” in screw connectors, but it will protect the surface of the copper against surrounding influence. Just silver is the best of all and that is mostly used when there is such harsh environmental conditions. Honestly its better to crimp thin pins on the wires, before inserting them into screw terminals. If the screw of the connector goes into direct contact with the wire, its a bad design. (The Meiji type) I would gues that the Bticino switches has a correct mechanism, as its a demand here in Europe. Plus, all stranded wire SHALL be fitted with a pin, unless the terminal is accepted to be for stranded wire. Which not many is.
John
May 14, 2011 at 11:37 am
Thereare only 2 reason that I could think of why electricians insist on using of stranded wires:
1. It is a lot easier to push and pull through conduit pipes also easier to loop inside connection boxes. ease & flexibility to work with
2. higher current carrying capacity.
Corrosion on copper wire is not limited to stranded wires only. Its caused by humidity on solid and stranded wires.
But in other city like in Olongapo, stranded wires were not allowed on house wiring. We’ll, that was in the 70′s
May 12, 2011 at 11:27 pm
Re Balikbayan Boxes–there’s so much competetion now, Bob, that it’s not as expensive anymore. We use Global Express in NJ–regardless of weight, door to door $48/box…thanks for sharing these tips!
May 14, 2011 at 12:24 pm
Natie, wow $48, that’s great!
Bob and Carol
May 12, 2011 at 5:22 pm
Hello Dave Star.
Stranded wire is NOT a potential problem at all. So please dont worry. Its so, that smaller dimensions it dont matter a lot if its a solid wire, mean 1,5, 2,5, 4 mm2 SQRmm. But then it starts to matter. The case is, that the current tend to flow in the surface of the copper wire, this because of magnetic reasons. So this will reduce the real properties of current leading, so instead its needed to use stranded wire. If you use the correct connection Technic, its not a problem to connect to any connector, just the connector is made for the dimension of the wire. Using a stranded wire in a direct screw connector without any protection, such as a pin, will lead to the copper floating over time, mas most people tend to use far too much power in the screwdriver. The spring supported connector always have the correct tension – pressure, even when the wire gets hot, and expands, and later crimp again. The screw do NOT follow the wire back again, but leave a small gap, and less tension on the connection.
The solution, cutting 1 strand or 2, is ok, as long as the reduced area is sufficient to lead the current in that place.
Greating from
John
May 12, 2011 at 5:00 pm
Hi Bob.
Most larger cables is always stranded wire types.
To get the individual wire to fit into the proper cable lugs, its necessary to press the wire into a solid wire first. Most tools have jaws for this purpose, after that, the jaws are changed to hexagonal jaws, and the cable lugs is then pressed onto the now correct diameter wire. Using stranded wire, its a demand here, that the wire is pressed into pins(thin tinned copper tube), and then inserted into either a screwed or a press connection on the plugs. Its a bit difficult to see if the wire dimension you bought can fit into the dimension of the connectors of the spring pressure type, but it might be possible. Just, it might not be able to find the correct tool for the job.
Take care
John
May 14, 2011 at 12:31 pm
John,
Thanks as always for your comments. Do you have any thoughts on tinning (with electrical solder) stranded wire (3.5mm) for use with outlets and switches having screw connectors?
Bob
May 12, 2011 at 12:04 pm
Another potential problem with starnded wire … perhaps it is not electrically or chemically significant — but I don’t like the idea of potential oxidation/corrosion amonsgt all the many strands.
Like you, I have been completely mystified as to why Philippine electricians insit on using stranded wire, but it’s annoying, and in some cases can be dangerous.
Mita and I are hoping to do a substantial rebuild of our home next year. One task I am going to compete early … send a shopping list to my son in the USA and have him buy a few boxes of cable and many, many outlets, switches, etc. It will be better in the long run to have a balik bayan box of electrical goodies shipped in advance.
Something else of note, I have an elderly aunt who has built ‘spec houses’ for yars in the Philippines … I think she is currently on her 15th or 16th house. She _Always_ goes to the US and buys all the plumbing fixtures … shows, bathroom sink hardware, kitchen faucets etc. in advance and ships them to herself in a balik bayan box.
May 12, 2011 at 3:32 pm
Hi Dave, thanks for your comment. Your aunt has a lot more experience than we do — 15 or 16 times more! I did send a few things from the U.S., but overall we’re happy with the price and quality of the things we bought here. We used HTC bathroom fixtures, American Standard faucets, Yale, Stanley and Schlage locksets, Hunter ceiling fans, lovely Malaysian tile and so forth. If you ship from the U.S. you have to pay $100+- for each balikbayan box plus sales tax in whatever state the purchase is made.
What I really wish is that I had access to the much bigger variety of building supplies available in Manila. If I was doing the house again, I’d spend time in Manila researching suppliers, not so much to save money but to get just exactly what we wanted rather than settling for whatever was available in Iloilo. Of course the vast bulk of big money materials have to be locally sourced concrete, rebar, sand, gravel, block, steel, roofing — although I do know of a guy who had cement shipped from the Cebu cement plant to Boracay. He used what he needed for his resort project and sold the rest at a profit.
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