*Note: The photo above is of a mis-assembled power connector. This is an example of what not to do, or Love becoming Electric – which is the topic of this conversation today.
Today, I want to talk about the electrical connections in your vintage machines. In particular, the topic will be when you’re using the machine and you feel a tingle, or a light shock, or buzzing sensation.
A couple of months ago, someone brought a website to my attention. The site positions itself and the owner as an expert in the field of vintage sewing machines, but they’ve made a statement that I have some concerns about as it pertains to this topic. I want to clear up some misconceptions about electricity and how it pertains to vintage sewing machines.
I’m paraphrasing how the site worded their statements, but I’m staying true to what was said.
Please note: I don’t want to start a war, I want people to be safe. This is why I’m not linking to the site, or quoting it.
- the wires in the foot controller could be wired improperly.
- the non-polarized cord could be plugged in wrong, and that turning it upside down can alleviate the issue.
First, a little bit of electrical theory.
Back in roughly the 30’s up until about 1962, in North America, new construction in houses could be done with unearthed sockets or what we would refer to typically as a “non-polarized plug”. This meant that the cord could be plugged into the wall in either direction, and it would work just fine. After this standard came in, devices continued to be shipped with non-polarized cords. In fact, several of the new and fairly new computer and electronic devices in our house have non-polarized plugs. Frankly, if it was possible to get an electrical shock from a device because it was plugged in backward, these plugs would have been banned by now, not grandfathered by the building code. There would be no non-polarized plugs on the ends of any of our devices.
After all, some countries in North America have gone so far as to ban Kinder Eggs.
Dangerous heart stopping, electrocution causing plugs would be banned for sure.
The cords were not polarized in the past, because it was not the “standard”.
The fact is, with non-electronically sensitive devices, like a vintage sewing machine – it truly does not matter which way you plug into an alternating current (AC) power receptacle.
With AC power, there is no constant positive and negative, hence no right or wrong way to plug the cord in.
Lincoln Electric, the makers of welders, says this about electrical polarity:
Alternating current (AC) flows half the time in one direction and half the time in the other, changing its polarity 120 times per second with 60-hertz current.
You don’t get to choose which way it flows by plugging in one way or the other.
This is also the reason a sewing machine motor doesn’t run in reverse if plugged in one way or the other, or if we switch the wires at the machine side.
The other thing to note about AC power, is that it requires a very small amount of it to disrupt the human heart. Less than 1 amp. Your wall plug is likely capable of supplying between 15 and 20 of those amps.
Typically, with 120volt service (In North America, this is what your wall plug is using, but not your dryer), you will be “thrown clear” in a potential electrocution situation, but it’s still not good for your heart, muscles, tissues, or peace of mind.
And it hurts.
Yes, unfortunately I speak from experience.
So let’s look at that. How did I shock myself? I thought I’d unplugged a machine, when in fact, I did something I’d never done previously, and not since, for the reason you’re about to read:
Instead of unplugging the machine from the wall, for some reason – I’ll claim it was lack of sleep – I unplugged from the machine and began working on the plug that had an open circuit (loose wires). It took me almost a minute, but eventually the inevitable happened. I shorted the 2 poles of the connector with my fingers. Luckily, as mentioned above, with 120V, typically the spasm will cause you to unclench, and I dropped the connector. As it was, when it initially happened, I couldn’t breathe for a few seconds, I curled up on the floor for “a bit” and my upper body, especially my chest, ached for days afterward. This did NOT trip the breaker, and typically won’t.
That scenario went straight past buzz to pain, but it’s all varying degrees of the same thing. When there’s a short in your machine, it’s being “shocked” with power the same way I was above. When you touch the machine while it’s being shocked, you become a part of the circuit, and get shocked, or “buzzed” too.
This is not to be played with. I don’t want to sound all doom and gloom, but it’s dangerous to believe that which way you plug it in will make the difference. It would likely be mandatory to change a plug out to a polarized one if simply plugging it in “wrong” could cause electrocution and fires.
Now let’s look at the statements.
1. the foot controller being wired backwards, or incorrectly.
The Singer bakelite foot pedal can’t be wired in reverse.
For example, you will notice that there is no mention of being careful which wire to put to which connector in either of these articles:
For the same reason as mentioned above – AC current doesn’t have constant polarity. All a foot pedal does is break one of the power wires going to the motor and add in some sort of resistance to allow variability of speed.
2. the electrical buzz goes away when I reverse the cable in the plug on the wall
I suspect the reason the problem went away when you unplugged and plugged it in the other way is that the wires that were shorting together were nudged apart by the movement, and are no longer shorting. This is a temporary condition, the cord or the wiring inside MUST be addressed for safety.
Typically the shock is caused by a wire that’s bare (rubbed so the wire is showing, or the insulation is simply missing) or loose and touching somewhere it shouldn’t. When this happens, the power follows the shortest route to “ground”. That’s through the body of the machine, and then through you.
So where could these bare wires be?
There are three main places where wiring are most likely to be compromised on a vintage sewing machine.
Working our way from least expensive to most:
- This wire -could- be in the pedal, but if it is, it’s likely to be the cord that’s the issue – If the cord set has a broken wire, it’s the easiest repair on the planet. Anyone can do it. It’s not a delicate operation that requires any special skills. It’s a simple job and the cord is held on by 2 screws. If you can manage a screwdriver, and take it “slowly” the first time, you can do this. The hardest part is routing the new cord so it sits flat. This is typically the least likely place for the issue to be. Here’s why: The last machine I serviced for a cord / pedal issue, the symptom was “machine went berserk, I had to unplug it to stop it” Most often, a short between the machine and the pedal manifests this way. Yours could be the exception though, so it warrants a look.
- I suppose it’s theoretically possible to have the pedal be the issue if the cushions on the bottom of the pedal were missing AND the cushion screws were sticking out and touching metal or water AND there was something wrong inside the pedal causing that screw to be touching part of the mechanism that’s carrying power. I really doubt that perfect storm would ever occur though.
- A heavily damaged connector. There’s bakelite between those connectors for a reason. With featherweights, for instance, the male connectors often get broken putting the machine into the case. I’ve had 15s and such with broken connectors too, and I can only assume that they were bashed into a wall or a table at one point. I often wonder how the table or wall fared in that battle. The female connectors are broken mostly from being too rough connecting and disconnecting from the machine.
- The wiring going to the motor or the light – the thumb nuts where you connect the cord to the machine – the ones that you see when you turn the machine over to oil / grease the bottom – could be hiding some bad wiring, or the rest of the wiring from the motor and light to the connector could be damaged. This is usually the most likely place, because usually the bare wire has got to be “touching” the item it’s using for ground (in this case, the body of the machine), which is what’s giving you the “buzz”. It’s possible too that the connectors are loose enough that the wires have slipped from where they’re supposed to be and touching each other. Simply tightening them is not enough, you need to put the wires back where they belong.
With most vintage machines, none of these scenarios is difficult to fix. As with any electrical repair though, if you’re not sure of your abilities, it’s better to have someone qualified look at it. I would have no concerns whatsoever though in encouraging someone to change a foot control cord using Jenny’s instructions above.
So, what if you decide not to fix it, and put it away for a bit? I would suggest that if this machine goes on the shelf, put a note with it, saying that it needs some electrical work. Better still if you know what it is, mention that too, or at least that it’s a shocking little thing. This way, down the road, if the machine goes to someone else without being fixed, they don’t have to relearn what you have here today.
One last point:
Singer and other manufacturers over the years have all recommended unplugging machines when not in use. This is largely to prevent fire risk. The carbon pile / bakelite button foot controllers, especially when improperly adjusted, can generate significant heat even when not being used, and potentially start a fire.
Many people think that by flipping the “switch” on the machine, they’ve cut the power off from it. Especially with vintage machines, this is often not true. A lot of the time, all that’s happened is the light turned off. Go ahead, give it a try. Press the pedal with the switch turned off. You may be surprised.