Measurements for a dedicated line


The question of whether a homeowner should get a dedicated line is often like "should I get bangs." It’s a little complicated. Here are a couple of reasons to consider not:

I. My experience is that you won’t eliminate all the other noise coming from your home even if you do run a dedicated line. I still hear motors switching on and off despite being on completely different circuits.

II. A little resistance and a little inductance may actually be a good thing in keeping noise out of your line, so overkill on the wire gauge may not help this.

Why you definitely should get a dedicated line, with thicker wiring:

 

Less voltage sag.

 

Voltage sag means that under load the resistance in the line will cause the AC cabling int he wall itself to consume some of the AC voltage, giving your gear less volts to work with. This sag is proportional to current, so the more amps your gear is drawing the more sag.

This sag is something you can measure. There are two things you need to look: The hot to neutral voltage and the neutral to ground.

With nothing on the circuit your N-E (neutral to earth or ground) should be 2V or less. If it’s significantly higher than that stop and call an electrician. That’s true for any circuit in your home. High N-E values are indicators of a problem which may be in the circuit or in the service wiring from outside to the panel.

What happens when you turn your equipment on and play music is that the line will sag. The H-N (hot to neutral) voltage will drop, and the N-E will go up. Some sag as you turn on big amps is normal. So long as you are not tripping breakers you are fine. What you want to measure is the sag after your system has stabilized and while it’s playing music.

Keep an eye on the N-E value, as this will be a good indicator of the sag independent of the incoming line voltage. It may also point out where you may have issues. That is, if you measure an extra 2V of N-E, your sag is probably around 4V, so you went from 120V to 116V and you can be relatively comfortable it isn’t outside influences.

Of course, any good multimeter will work for this but I like plug in meters with built in N-E measurements. This one is cheap, and the N-E may not be hyper accurate, but it is the only device I’ve found on Amazon that will show you both the H-N and N-E voltages at the same time.

The nice thing about any plug-in type voltage meter is you can watch it over  a couple of days without hand holding probes in the socket.

If you find another which does both please post.

 

 

erik_squires

N-E volts 00 with the microwave on or off

Those figures were all based on using the KAIWEETS tester. I have other DMM’s which are much more accurate. Since I’m discovering my readings are now in the mV range, I won’t be using the KAIWEETS tester for these readings anymore.

You will get the same measurements on a bootleg ground.

I’ve visually inspected my outlets. They don’t have bootleg grounds...make that anywhere in my house. When I first moved in in 2001, I inspected, and changed out every outlet, along with numerous wall switches. I would have never allowed any bootleg grounds if I had encountered them. I would have recognized them even in 2001.

It looks like *this* is the ultimate outlet tester.

Ideal SureTest Circuit Analyzer

You Tube demonstration of Ideal SureTest Circuit Analyzer

@dpop - A GFCI outlet senses differences in current at the outlet between the hot and neutral. A voltage on the ground won’t cause this, necessarily. A leak between neutral and ground at the appliance connected would.

In fact, GFCI outlets don’t even need a working ground, so can be used to retrofit outlets without a ground conductor.  If all is well, the current flowing from hot and through the neutral back to the panel should be identical.

The theory of voltage differences between neutral and ground is related to whether or not current is flowing.  Since ground should have no current, it should also have the same voltage as at the panel. Neutral on the other hand, when it has current flowing through it, will be lifted from ground by the imperfect resistance of the copper wire.

Ohms Law:

Volts = A * R

So with 1 Amp, and a resistance of 0.1 Ohms you should see Neutral lift to 0.1V above ground.

The ground conductor also follows the same math, but:

Volts = 0 Amps * 5 R = 0 Volts

That is, from one end of the ground to the other is still 0 Volts. 

I got the Kaiweets off of Amazon. It is showing a voltage fluctuation between 119 and 122 volts. It is gradual throughout the day. The higher readings tend to be late at night when I favor what is coming out of the system. However, since injectiing the Audions into the picture I can't say I hear as much difference. The previous situation was tube pre and power while at this moment it is just the pre with the tube power amp on the sidelines.