6 ms·

As far as I know... there's no documentation of home power systems in the US. So the difference between "electrician installed" and "mysterious, unknown person

by ethbro 8y ago

As far as I know... there's no documentation of home power systems in the US. So the difference between "electrician installed" and "mysterious, unknown person installed" is only in the finished product.

ams6110 8y ago
Indeed. It happens all the time that a homeowner does significant wiring projects in their own home. Everything you need is available at the local hardware store or Home Depot. Some do a good job. I've also seen things like lamp cord used in fixed wiring behind walls or in attics.
- 13of40 8y ago
  I inherited some piece of furniture - I don't recall what - that my wife's ex had attached a florescent lamp to. He used a telephone cord for the 120v power connection.
  - ethbro 8y ago
    People who can't explain how current, voltage, and resistance relate to each other shouldn't be allowed near wiring.
    - ScottBurson 8y ago
      A fluorescent lamp that one would attach to furniture probably only takes 10W. That's less than 100mA at 120V; a telephone wire can handle that. Also, telephone wires once carried as much as 50VDC for ringers, so I'd expect the insulation to be adequate, if only barely. The biggest problem, I think, is that because the insulation is relatively thin, there's a greater risk of mechanical damage to it.
    - ams6110 8y ago
      One slightly obscure example is someone using a European (220V) light fixture or extension cord (with plug adapters) in North America. (110V). The current for the same wattage will be roughly double in North America. So lamps, etc. intended for use in Europe will have wiring that is undersized for the current draw if used in North America.
- randysavage 8y ago
  > I've also seen things like lamp cord used in fixed wiring behind walls or in attics. We found exactly that, lamp cords and extension cords, when we started our remodel a month ago. The former owner did some renovation ten years ago, and was an architect so we always assumed he did a decent job. That was one of a few questionable choices he made, so we're now re-wiring the entire house.
sgc 8y ago
An old house that is rewired would have a permit on file if it were done properly, and includes the name of the contractor if there is one. But there is often no proof on site.
- ghaff 8y ago
  Electrical work can be done properly without a permit having been pulled. Depends on where I suppose but even contractors often don’t get permits.
  - TheSpiceIsLife 8y ago
    In Australia all work carried out by an electrician is required to be certified. That is to say, the electrician must, on completion of the work, hand you a certificate stating that all work is to the relevant standard. They can't reasonably withhold the certificate, and it must be provided on completion not on payment. An organisation called TechSafe[1] is charged with carrying out random inspections. 1. https://www.techsafe.com.au/ https://www.techsafe.com.au/
  - sgc 8y ago
    I include pulling a permit as part of doing a job properly.
todd8 8y ago
I had house that had a high quality ceiling fan that always made noise. It was high and hard to reach but after perilous ladder work I discovered it wasn't the fan; it had been wired up wrong, the variable speed control was wired up across the two separate 120v legs supplying the home with electricity. I was surprised that the fan even worked at all that way. I don't know who wired it up originally. I'm not an electrician so correct me if I'm wrong, but for those unfamiliar with residential wiring in US homes, ordinarily homes are supplied with two out of phase 110VAC lines. Heavy appliances like electric clothes driers and electric car charging points use the 220VAC that I available between the two "hot" lines. Everything else in the house use either one of the "hot" lines (black wires according to the national electrical code). There are actually 3 wires going to each outlet, light, etc. though the house: one black (belonging to one of the two sources of 110VAC), one white (called the neutral line, approximately 0V above ground, and one green a separate green wire that is connected to ground around the point where power enters the house.
- dgacmu 8y ago
  Correct, but they're 120/240V. Or at least, should be.
  - nwallin 8y ago
    It's actually 120V/~208V. If you're feeling frisky, you can confirm this by going around between random pairs of outlets in your house and comparing the right slots from two different outlets until you find a pair of them that are out of phase from each other. Fundamentally, the power grid is based on three phase power. Typically, the average telephone pole will have four power wires on it, and one or two thick bundles of phone line or maybe cable TV, I dunno. Three of those four power lines are the three phase electricity, and the fourth is the common neutral line that is ideally near 0V, but typically fluctuates a bit. Only three out of those four lines enter your house. One is is the neutral line, the other two are just two of the three power lines. Those two power lines are not 180 degrees out of phase, they are 120 degrees out of phase. If they were 180 degrees out of phase, the math is simple: it's obviously just 240V. Since it's 120 degrees out of phase, you end up with a sine wave that looks something like 120\(sin(x)-sin(x+pi\2/3)). (only you need to adjust it for frequency) If you're better at your trig identities than I am, you can calculate that out exactly, but for simpletons like me I just plug it into my calculator and find a local maximum of 207.846 something. (note: In the US, we use neutral and ground to refer to the common center of the three phase power, and the wire that is buried in the ground near your house, respectively. In the UK, I think they call these two wires ground and earth, respectively. Note that the term "ground" has a very different meaning (read: one of them can kill you, the other one keeps you safe) depending on the context.)

by ethbro 8y ago

ams6110 8y ago

Indeed. It happens all the time that a homeowner does significant wiring projects in their own home. Everything you need is available at the local hardware store or Home Depot. Some do a good job. I've also seen things like lamp cord used in fixed wiring behind walls or in attics.

13of40 8y ago
I inherited some piece of furniture - I don't recall what - that my wife's ex had attached a florescent lamp to. He used a telephone cord for the 120v power connection.
- ethbro 8y ago
  People who can't explain how current, voltage, and resistance relate to each other shouldn't be allowed near wiring.
  - ScottBurson 8y ago
    A fluorescent lamp that one would attach to furniture probably only takes 10W. That's less than 100mA at 120V; a telephone wire can handle that. Also, telephone wires once carried as much as 50VDC for ringers, so I'd expect the insulation to be adequate, if only barely. The biggest problem, I think, is that because the insulation is relatively thin, there's a greater risk of mechanical damage to it.
  - ams6110 8y ago
    One slightly obscure example is someone using a European (220V) light fixture or extension cord (with plug adapters) in North America. (110V). The current for the same wattage will be roughly double in North America. So lamps, etc. intended for use in Europe will have wiring that is undersized for the current draw if used in North America.
randysavage 8y ago
> I've also seen things like lamp cord used in fixed wiring behind walls or in attics. We found exactly that, lamp cords and extension cords, when we started our remodel a month ago. The former owner did some renovation ten years ago, and was an architect so we always assumed he did a decent job. That was one of a few questionable choices he made, so we're now re-wiring the entire house.

sgc 8y ago

An old house that is rewired would have a permit on file if it were done properly, and includes the name of the contractor if there is one. But there is often no proof on site.

ghaff 8y ago
Electrical work can be done properly without a permit having been pulled. Depends on where I suppose but even contractors often don’t get permits.
- TheSpiceIsLife 8y ago
  In Australia all work carried out by an electrician is required to be certified. That is to say, the electrician must, on completion of the work, hand you a certificate stating that all work is to the relevant standard. They can't reasonably withhold the certificate, and it must be provided on completion not on payment. An organisation called TechSafe[1] is charged with carrying out random inspections. 1. https://www.techsafe.com.au/ https://www.techsafe.com.au/
- sgc 8y ago
  I include pulling a permit as part of doing a job properly.

todd8 8y ago

I had house that had a high quality ceiling fan that always made noise. It was high and hard to reach but after perilous ladder work I discovered it wasn't the fan; it had been wired up wrong, the variable speed control was wired up across the two separate 120v legs supplying the home with electricity. I was surprised that the fan even worked at all that way. I don't know who wired it up originally. I'm not an electrician so correct me if I'm wrong, but for those unfamiliar with residential wiring in US homes, ordinarily homes are supplied with two out of phase 110VAC lines. Heavy appliances like electric clothes driers and electric car charging points use the 220VAC that I available between the two "hot" lines. Everything else in the house use either one of the "hot" lines (black wires according to the national electrical code). There are actually 3 wires going to each outlet, light, etc. though the house: one black (belonging to one of the two sources of 110VAC), one white (called the neutral line, approximately 0V above ground, and one green a separate green wire that is connected to ground around the point where power enters the house.

dgacmu 8y ago
Correct, but they're 120/240V. Or at least, should be.
- nwallin 8y ago
  It's actually 120V/~208V. If you're feeling frisky, you can confirm this by going around between random pairs of outlets in your house and comparing the right slots from two different outlets until you find a pair of them that are out of phase from each other. Fundamentally, the power grid is based on three phase power. Typically, the average telephone pole will have four power wires on it, and one or two thick bundles of phone line or maybe cable TV, I dunno. Three of those four power lines are the three phase electricity, and the fourth is the common neutral line that is ideally near 0V, but typically fluctuates a bit. Only three out of those four lines enter your house. One is is the neutral line, the other two are just two of the three power lines. Those two power lines are not 180 degrees out of phase, they are 120 degrees out of phase. If they were 180 degrees out of phase, the math is simple: it's obviously just 240V. Since it's 120 degrees out of phase, you end up with a sine wave that looks something like 120\(sin(x)-sin(x+pi\2/3)). (only you need to adjust it for frequency) If you're better at your trig identities than I am, you can calculate that out exactly, but for simpletons like me I just plug it into my calculator and find a local maximum of 207.846 something. (note: In the US, we use neutral and ground to refer to the common center of the three phase power, and the wire that is buried in the ground near your house, respectively. In the UK, I think they call these two wires ground and earth, respectively. Note that the term "ground" has a very different meaning (read: one of them can kill you, the other one keeps you safe) depending on the context.)