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diy solar

Order of ac outlets on branch circuit

Hedges said:
Put 12A through that (if you're in the 120V world) and you get 19 mV/foot. Outlets 5' apart would be 100 mV different.
Click to expand...

A good an idea as that is, mains voltage stability would likely swamp the difference making it hard to tell if the meter had been moved 5' or 5 miles (ok, slight exagfgeration ;) )
 
JoeHam said:
I won’t pretend that I completely understand the purpose of this thread but there is a relatively new tool out in Amateur radio circles that is dirt cheap (around $50) and can be used to find impedance bumps in RF transmission lines.

Google NanoVNA and see if it’s helpful for this use case. I’m only using mine to check SWR but it’s capable of so much more.
Click to expand...
That is a very cool gadget. I wish it worked up to 2.5 GHz or so.
 
gnubie said:
A good an idea as that is, mains voltage stability would likely swamp the difference making it hard to tell if the meter had been moved 5' or 5 miles (ok, slight exagfgeration ;) )
Click to expand...

Not a problem if you measure from hot of one outlet to hot of the next (or neutral to neutral). This is where the extension cord comes in.
Then a 10% variation in line voltage will only cause a 10% variation in the 100 mV reading, 5' 6" vs. 5' 0".

Only a two orders of magnitude exaggeration - would have been 5' vs 500', so might as well have been 5 miles for his purposes!
 
Probably easier to just go with the long leaded meter and measure the ohms of the circuit directly then.
 
gnubie said:
Probably easier to just go with the long leaded meter and measure the ohms of the circuit directly then.
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I usually see about 0.5 ohms contact resistance. It'll probably vary from socket to socket. With < 2 mOhms/foot of wire, need a 4-wire ohm meter.

1600315428708.png

Using a separate 12A current source accomplishes the same thing, and gives a signal 10's of mV per foot.

Last time I tried measuring automotive fuses I wasn't getting much resolution with my bench meters, so I used a several amp power supply (with 4-wire feedback) instead, and that worked well.

diysolarforum.com

Testing automotive fuses

After watching a video (sorry can’t find it now) showing resistance testing of cheap fuses and name-brand ones, I decided I’d better test the ones I’ve put in our cars. In the video, it was said that previously Harbor Freight sold fuses, but later recalled them and didn’t carry anymore. Fuses...
diysolarforum.com diysolarforum.com
 
When I refer to a meter with a long lead I am actually referring to a proper test meter for mains wiring testing. My mistake, didn't actually say that in my original post, just 'test gear'. Obviously a standard meter that puts 3V at piddly current across the wire is going to have a hard time of it.
 
gnubie said:
When I refer to a meter with a long lead I am actually referring to a proper test meter for mains wiring testing. My mistake, didn't actually say that in my original post, just 'test gear'. Obviously a standard meter that puts 3V at piddly current across the wire is going to have a hard time of it.
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Have a link to what those are?

I'm not familiar with them, and a quick search just turns up typical DMM.

Thanks.
 
Don't quote me on this specific model, I'm not a sparky and don't do this stuff myself. It's only from my general knowledge.

Installation testers

Eliminate accidental damage with electrical installation testers. Fluke's 1664, 1663 and 1662 multifunction testers are built to protect people, electrical systems and buildings against things such as electrocution, fire and other equipment damage. Browse today.
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gnubie said:
Don't quote me on this specific model, I'm not a sparky and don't do this stuff myself. It's only from my general knowledge.

Installation testers

Eliminate accidental damage with electrical installation testers. Fluke's 1664, 1663 and 1662 multifunction testers are built to protect people, electrical systems and buildings against things such as electrocution, fire and other equipment damage. Browse today.
www.fluke.com www.fluke.com
Click to expand...

Interesting ... not sure if this $2000 to $4000 meter would do what Joey wants as well as the electric radiator heater setup I proposed, but it does estimate prospective fault current up to 50 kA based on voltage and resistance. Appears it measures resistance out the utility lines, through transformer, and back.

It also includes hipot for insulation and ground-fault device tester. Doesn't mention arc-fault, a device required in new house wiring for US.

These pages reference vendor's site in Australia, and mention tests used in the U.K. Here in the U.S. we just slap in wires/boxes and the inspector visually checks them. Maybe the utility does some better tests, also maintenance of industrial facilities.
 
At the time I thought it was more of a 'How could this be done' rather than a practical "I'm going to do this so how should I go about it" question. :)

Installations here have to be checked as part of the job and the job itself can only legally be done by a licenced sparky. There's no run your own wire and get a 3rd party inspector to glance sideways at it and sign off.
 
Probably pointing to the test set a post or two above it, looks a lot like a tone sender used for tracing phone / network cables but set up specifically for tracing mains wiring.
 
It was a 1/4 baked foolish response that was meant to inject humor, and I linked the wrong comment at that. Please just ignore it. I'll show myself out.
 
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