Grounding Vintage Sewing Machines
06-08-2014, 08:41 PM
#51
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Originally Posted by manicmike
I see sticking a fork in the toaster as a challenge and do it often. It's like a more exciting version of "Operation" 
06-08-2014, 09:08 PM
#52
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Originally Posted by Jamesbeat
I think I've thought of a way around this, and I'll take photos along the way in case others want to do the same
06-08-2014, 11:58 PM
#53
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Location: Brisbane, Australia
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Originally Posted by Sunflowerzz
Well, I wouldn't mind making my vintage machines more safe
Take pictures before removing any old wires. Maybe it's just me but one gets wire colour amnesia very quickly.
Unplug the machine before trying anything (don't just switch it off, someone could have re-wired your socket so that live is always on instead of neutral), particularly removal of motor brushes
- electrocuted myself doing just that the other day
06-09-2014, 03:42 AM
#54
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I don't know what the modern electrical safety requirements are, but a modern electrical device isn't going to be any safer than a 60-year old electrical device, if the insulation on the wiring is in bad shape.
I'd just wire in a modern electronic foot controller and be done with it.
I'd just wire in a modern electronic foot controller and be done with it.
06-09-2014, 04:47 AM
#55
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Originally Posted by mlmack
I don't know what the modern electrical safety requirements are, but a modern electrical device isn't going to be any safer than a 60-year old electrical device, if the insulation on the wiring is in bad shape.
I'd just wire in a modern electronic foot controller and be done with it.
I'd just wire in a modern electronic foot controller and be done with it.
06-09-2014, 05:33 AM
#57
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No, I'm 100% correct.
The appliance will either be double insulated (a plastic casing counts towards this) or it will be grounded.
It's all in the Underwriters Laboratories regulations. There is an exception for appliances with exposed heating elements such as toasters.
Google IEC 60335 if you don't believe me.
The appliance will either be double insulated (a plastic casing counts towards this) or it will be grounded.
It's all in the Underwriters Laboratories regulations. There is an exception for appliances with exposed heating elements such as toasters.
Google IEC 60335 if you don't believe me.
10-05-2017, 12:59 PM
#58
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Actually, this is not true. Ohm's Law comes into play here.
You're right that current kills, but wrong about the amount of current a body will draw at 240 Volts.
E (or V) = IxR, or Voltage (Potential) = Current x Resistance. Your body's resistance will be pretty much constant, but for twice the voltage you will actually draw twice the current.
Motors that take 240V are designed to draw half the current of a 120V motor in order to get the same amount of power, which is where P= VxI comes into play.
tabby and spouse
BSEE and MSEE
You're right that current kills, but wrong about the amount of current a body will draw at 240 Volts.
E (or V) = IxR, or Voltage (Potential) = Current x Resistance. Your body's resistance will be pretty much constant, but for twice the voltage you will actually draw twice the current.
Motors that take 240V are designed to draw half the current of a 120V motor in order to get the same amount of power, which is where P= VxI comes into play.
tabby and spouse
BSEE and MSEE
Originally Posted by manicmike
Like I already said, the opposite of this is true. For anyone who wants to know why:
Power = voltage times current, or P = V I
If you want a motor to have the same power with twice the voltage, you need to reduce the current (I) by half. Higher voltage and lower current is safer. This is why the UK and Australia chose a higher voltage standard than the U.S.
As another example: Ever get a zap from your car's spark plugs? Sure it'll send you across the garage floor because the voltage is extremely high (around 30,000 volts) but nobody ever dies from the electric surge because the current is correspondingly low.
Regarding the article from 1952 that James quoted from. This was outback Australia in 1952 where they used 32 volts DC as mains supply. Therefore not at all supportive of your point. Sixty two years ago things were very different. You can't just quote something out of context.
Also James, if you worked in electronics I'd have expected you to know the basics of electrical theory such as P=VI
Power = voltage times current, or P = V I
If you want a motor to have the same power with twice the voltage, you need to reduce the current (I) by half. Higher voltage and lower current is safer. This is why the UK and Australia chose a higher voltage standard than the U.S.
As another example: Ever get a zap from your car's spark plugs? Sure it'll send you across the garage floor because the voltage is extremely high (around 30,000 volts) but nobody ever dies from the electric surge because the current is correspondingly low.
Regarding the article from 1952 that James quoted from. This was outback Australia in 1952 where they used 32 volts DC as mains supply. Therefore not at all supportive of your point. Sixty two years ago things were very different. You can't just quote something out of context.
Also James, if you worked in electronics I'd have expected you to know the basics of electrical theory such as P=VI
10-05-2017, 01:16 PM
#59
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I work at a big agency. We moved to a new building. Some of our equipment got modified for the new setting. My 2 wire stereo received a 3 prong plug. No additional wire or ground, just a plug. Oh yea, I felt safer ( cough)
10-05-2017, 02:31 PM
#60
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Posts: 1,963
I'm not an expert, but it looks like a lot of the old Singer motors are up to the standards of today. My 1950s belt driven machines are all marked with a square within a square, in other words double insulation. I have never seen modern domestic machine with true grounding (tree core wire), the have double insulation. As far as I know double insulation or grounding isn't strictly required unless you are working out doors, near a zink, bath rooms or something like that.
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