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[Rob Spence]

I wish... Since the ground breaking is in a neighborhood, the closest I can get is a dryer plug, which I don't have a distro for.

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If you have a 50a distro, a 14-30 to 14-50 adapter will work and should be ok.


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[Brandon Scopel]

If you have a 50a distro, a 14-30 to 14-50 adapter will work and should be ok.


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I am looking for one to rent.

[TomBoisseau]

Here's a terrific little tester for checking voltage loss (and quite a few other things).  You can set it to measure what the voltage would be on the line if you had a 12, 15, or 20 amp load.  It also checks for proper wiring, ground to neutral voltage, frequency, peak, rms, hot, neutral, and ground impedance, etc.

It's really a terrific device, howbeit a bit pricey. I'd had mine now for probably 8 years and I REALLY like it.

Tom

http://www.idealindustries.ca/products/test_measurement/circuit_analyzers/suretest_circuit_analyzers.php

[Corey Scogin]

Measured about 110v (no load) at the far speakers.  I'm guessing the outside outlet I had access to was dedicated and close to the panel as there was little voltage drop when loaded.

Frank, I'm just curious, did you check the voltage at the outside outlet with no load?  No load should mean no voltage drop whether at the outlet or at the far end of the run.

[David Sturzenbecher]

Hey, wait a minute! Maybe it wasn't a voltage loss. Maybe because I jumped one speaker off of the other, it was an output impedance thing. If so, even a short electric run would have cause the same result.

No


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[Peter Morris]

I just did a little gig for a local groundbreaking ceremony. The client had asked for a microphone, podium, and two speakers on poles. Because it was outdoors, I suggested a generator, but she didn't like that idea at all. There was a nearby building, (over 100 feet away,) and the client had gotten permission from the owner to use their exterior power outlet. (US 120V)

After more detailed discussion and a little measuring, I learned that she wanted one speaker positioned 150 feet from the power outlet and the other speaker positioned at 250 feet away. I was concerned about current draw and needed to do a little homework before I committed.

A few Google sources told me that for 12 gauge cabling, at 200 to 300 feet, the load should not exceed 4 or 5 amps. I decided to use my DSR112 speakers because they are more efficient and don't draw as much current as my older amp and speakers. (The spec book says that 1/8th power is 100 watts.) For a mild mannered speech, I figured it will probably not exceed that draw. Besides, I didn't think that I could get away with using passive speakers which may have required a 100 foot speaker cable run.

I tested out the whole rig at home and the DSR's worked great. The first 100 feet was through my good 10/3 extension cord. The remaining distance was through various lengths of 12/3 SOOW power cables. None of the cables got hot. However, the speaker at 250 feet would not go as loud as the one at 150. I assume that was due to a voltage drop caused by resistance at that distance.

I didn't have any means of measuring current or voltage that day, but I'm guessing total load was probably less than 2 amps and the far speaker never shut off due to low voltage.

Anyway, the event was a success and the client was happy. Though, I doubt that I could have gotten away with using a larger system or greater distance.

I'm not exactly sure what the situation is in the US, but that that length and size of cable may be illegal.  Its not about the equipment operating correctly, but under fault conditions ensuring that the fault protection on the electrical installation works correctly.

https://en.wikipedia.org/wiki/Extension_cord

Mike Sokol may be able to provide some assistance ??

[Stephen Swaffer]

I tested out the whole rig at home and the DSR's worked great. The first 100 feet was through my good 10/3 extension cord. The remaining distance was through various lengths of 12/3 SOOW power cables. None of the cables got hot. However, the speaker at 250 feet would not go as loud as the one at 150. I assume that was due to a voltage drop caused by resistance at that distance?

Why would you expect the cables to get hot?  Would you expect a 25 ft #12 cord carrying 2-3 amps to get warm?  The voltage drop and heat produced will be the same no matter if that cord is used alone or in the middle of a 300 foot run.

Voltage drop needs to be considered at peak draw, while ampacity is concerned with average draw (1/8 wattage rule).  Two related, but separate considerations.

[Stephen Kirby]

I would expect the connectors to get hot before the cable did.  That's where the most resistance is.

As for the dryer plug, you should have a short pigtail to a CA female or whatever your distro uses.  Then you bring a dryer or stove or whatever, which you can usually grab at Home Depot, meter the service to be sure what is where and then hook up your pigtail.  I have a small collection of plugs that I take on and off a 2' pigtail as needed.  Or sometimes I've had to hook the pigtail directly to a box.  An extra CA plug isn't cheap but a couple feet of 6/4 and a dryer plug isn't much.  As they say in the Boy Scouts, Be Prepared.

[frank kayser]

Frank, I'm just curious, did you check the voltage at the outside outlet with no load?  No load should mean no voltage drop whether at the outlet or at the far end of the run.

Hmmm...
No, I did not check at the outlet.
Maybe I'm doing it wrong.
I was under the impression that there is voltage drop at the end of a long run, loaded or unloaded due to resistance in the wire.  Does the drop only occur with a load? And is that loss in some way mathematically related to the load vs distance?
So if I were to measure a LOADED extension, I would get one voltage at the end of the cord, and get another higher voltage at the outlet (with extension and load attached?)
frank

[Corey Scogin]

Hmmm...
No, I did not check at the outlet.
Maybe I'm doing it wrong.
I was under the impression that there is voltage drop at the end of a long run, loaded or unloaded due to resistance in the wire.  Does the drop only occur with a load? And is that loss in some way mathematically related to the load vs distance?
So if I were to measure a LOADED extension, I would get one voltage at the end of the cord, and get another higher voltage at the outlet (with extension and load attached?)
frank

Yes, the voltage is related to the current (load) and the resistance (distance and wire size).

Look up Ohm's Law and voltage divider.
In the diagram below:
V_in is your power source (the outlet for example)
R₁ is the resistance of your extension cords
V_out is the voltage at the equipment.
R₂ is the resistance of the equipment.

Ohm's Law says Voltage = Resistance * Current or for this case Current = Voltage / Resistance.
With no equipment connected (or all equipment off), the value of R₂ is effectively infinite so the current is zero and the value of R₁ is irrelevant unless it's also infinity (open circuit). Zero current means zero voltage drop across R₁.

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