What type of wire for dedicated 20A AC lines?


I’m about to have two 20A dedicated lines installed. What type of wire should I use? I know there are differences of opinion on whether to use 10 AWG or 12 AWG, however the link below makes a great case for using even 8 AWG solid core copper on longer runs like mine will be (50 ft), to ensure a lower resistance, lower voltage drop over the long run, and therefore more access to instantaneous current for my Gryphon Diablo 300. The wire would need to be stepped down to 10 AWG to connect with the receptacle. The article actually states that the thickness of the wire is more important than the fact that it is dedicated…

Assuming I want to follow this advice, which again makes sense to me, where would I find such wire to give to my electrician?

 

nyev

jea48 said:

Where was your reference point used for the measurement? At the electrical panel?

ieales response:

Where else?

Usually the no load voltage is checked at the last outlet on the branch circuit. No loads are connected to the circuit. If a difference of potential, voltage is present it will be the same as the applied voltage at the feed end. In this case the branch circuit breaker to neutral bar voltage.  If 120V at the panel it will measure 120V at the end of the branch circuit that has no load connected to it. (Add load and then measure again for VD.)

Why? Simple Ohms law. You need a load to have a VD. No load no VD. The internal resistance of a typical DMM is about 10M ohm. 

     jea48 said:

What type of volt meter did you use?

ieales response:

calibrated Fluke.

10M ohm internal resistance. 120V / 10M ohm = 0.000012 amp.

 

Jim

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@kijanki

+1

 

Please explain what happens if the power transformer’s secondary winding voltage is lower feeding the rectifier, due to a quick AC mains VD event, and the electrolytic capacitors voltage is higher. Just going from memory the rectifier will not conduct and the caps do not get recharged for that "(millisecond pulse)" in time.

 

Jim

I recently installed a dedicated 20 amp, 8 gauge multi-strand run.  The run is 123 feet in length first going to a 30 amp locking plug (that goes to my surge protector) within the entertainment console then an additional 2 feet to a pair of 20-amp, hospital-grade plugs at the termination outside of the console.

The 8-gauge wire is maintained all the way from the panel to the three outlets (including the hospital-grade recepticles) and there are no junction boxes along the way.

And just because I had it, I put a big ferrite bead over the wire where it comes out of the panel.

This cleaned up a bunch of "hash" on my Yamaha SACD, but less so on my Oppo95, which has a better power supply.

@jea48   You are right - there will be no current thru rectifiers until capacitor voltage will drop below rectifier supplied peak voltage.  Theoretically it is possible to build LPS where capacitors keep average instead of peak voltage, but it requires huge inductor in series (in order of Henries) made with thick wire and AFAIK nobody is doing it.  One problem is lower rail voltage (average instead of peak) while the other is dependency on the load current.

http://www.r-type.org/articles/art-144.htm

This stuff is awesome and I barely comprehend the explanations, but it sounds like there are strong arguments that I’m going to really going to enjoy my big fat 10AWG wires with lower resistance, enabling more rapid access to glorious peak current, all for like two hundred bucks extra, give or take. And if the anti 10-gauge crew end up being right and it does nothing, the extra bucks will totally still be worth it knowing those big fat wires are providing the juice!  Can’t go wrong.