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Am I hearing things?

I just an extra  new dedicated line run beside the other one. with 10 gauge wire, 30 amp breaker and a 20 amp rated outlet. I don't think it sounds as good!!! What the hey. A little shrill in both vinyl and CD. I'm comparing from what it sounded like last night. Does electricians wire, breaker and outlet have to burn in? Am I alone in this. I'm have a whole system AC but in and the temp got up to 80. Maybe that is why. Also I'm listening at 11 am EST. So the power grid may have an affect. Did I just answer my own question or have other people experienced this. The original dedicated line was put in in 03 with 12 gauge wire, 20 amp breaker and a 15 amp outlet. Are these 2 lines picking up interferrence? 
blueranger

Showing 6 responses by jea48

jea48
2,944 posts
 
I just an extra new dedicated line run beside the other one. with 10 gauge wire, 30 amp breaker and a 20 amp rated outlet. I don’t think it sounds as good!!!
@blueranger

Just a guess a licensed electrician did not install the new wiring. A qualified licensed electrician would not install a 30 breaker to feed a 20 amp rated receptacle. The 30 amp breaker should be replaced with a 20 amp breaker. (The contacts inside a 20 amp breaker are the same as found in a 30 amp breaker. Exactly the same. Only the thermal and magnetic trip units are different.)

What type of wiring did you use? 10-2 with ground Romex?

Is the new circuit installed on the same Line, Leg, as the other dedicated circuit? In the same area space in the electrical panel as the other circuit’s breaker?

One thing you should check is to make sure the AC polarity is correct at the receptacle outlet. Go to Home Depot and buy a cheap plug-in circuit/polarity checker to make sure the polarity is correct.


jea48
2,944 posts
 
craigl59
248 posts                                                                         08-03-2018 10:36am

Since there are electricians seeing this thread would like to ask them if 12/2 Romax is OK for 20 amp circuits. Is there some reason why 10/2 seems to be preferred in many audiophile installations? Is it the concept of "Overwire and Underbreaker?"

Per NEC (National Electrical Code) #12 copper wire is the bare minimum wire size for a 20 amp branch circuit. NEC does not prohibit using a wire size larger than #12. Usually a larger wire size is used for VD (Voltage Drop) that may occur on the conductors of the branch circuit due to the connected load. The connected load does not need to be a continuous connected load. It could be caused by a fluctuating load.

The size of the breaker, overcurrent device, dictates the ampere rating of the branch circuit. The OP has a 30 amp breaker, therefore the circuit is 30 amps. Per NEC you can not install a 20 amp rated receptacle on a 30 amp branch circuit. Per code the breaker must be 20 amp.

Here is an old Link, but still holds true for when a breaker is supposed to trip if overloaded.
https://goodsonengineering.com/wp-content/uploads/2017/08/CircuitBreakerMyths_web.pdf
jea48
2,944 posts
 
blueranger OP
255 posts                                                                            08-03-2018 3:05pm

I called the electrician and he said it was a 25 amp breaker. He assured me I’m fine. Mike
Call him back and ask him to cite the section in the NEC code that said he can use a 25 amp breaker where a 5-20R (20 amp) duplex receptacle is installed on a branch circuit.


Have him look at NEC
110.3 (B)

210.21 (B) (3).
Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21 (B) (3), ......


Table 210.21(B)(3)
Circuit rating (Amperes) ............Receptacle rating (Amperes)
20 amp ............................................... 15 or 20 amp
30 amp .................................................. 30 amp

If you have had problems with nuisance tripping with a 20 amp breaker I would suggest the electrician check and see if the Electrical Panel manufacturer makes an HM (High Magnetic) circuit breaker. An HM breaker has a longer lag time for inrush current.

In an earlier post I asked you a few questions. The questions asked relates to the problems you are experiencing with the sound from your audio system, when connected to the new dedicated circuit.

.
jea48
2,944 posts
 
blueranger OP
257 posts 08-03-2018 5:32pm

I will get a polarity tester and I don’t kniw tbe particulars. But I do know when I saw the wire it was orange 10 ga and there was no ground wire in it. So how could he ground it otherwise? I’m just going to get another electrician verify everything and quote this post. Thanks Mike

Stop. Take a deep breath. Don’t jump to conclusions. Other than the breaker the electrician installed in the electrical panel, everything else of the installation may be fine.

#10-2 with ground NM-B cable (Romex is a Trade name of) has an outer orange sheath, jacket. It comes with a bare equipment grounding conductor. It doesn’t come without an equipment grounding conductor.

The electrician installed one wall cut-in box and installed one 20 amp duplex receptacle. Correct? Metal or plastic box? Do you know the make of the duplex outlet? Is it at least a spec grade outlet? The outlet could be the source of the sound you are hearing from your audio system.  What type of duplex cover did he install? A flexible non breakable nylon plate?

Go to the electrical panel. What breaker number on the panel schedule is the older dedicated circuit you already have? What is the breaker number of the new dedicated circuit? The number is also stamped on the panel front cover next to the breakers. The numbers will tell me if the electrician install the new dedicated circuit breaker on the same Line, Leg, as the old dedicated circuit breaker.

Pick up a circuit/polarity tester at Home Depot. $5.00
https://www.homedepot.com/p/Power-Gear-3-Wire-Receptacle-Tester-50542/206212329?cm_mmc=Shopping%7CG%...
Post back what it indicates. Hopefully it will indicate CORRECT

Jim


jea48
2,944 posts
 
I looked downstairs in the electrical panel and no and nowhere is there a 15, 20, 25, or 30.marked on the breakers. Is there a secret code electricians use?
The ampere rating should be on the ON/OFF breaker handle. Sometimes it’s printed on the face of the breaker. The ampere rating should be visible on the front of the breaker for the user to see. What manufacture electrical panel do you have?

Example.
20 amp breaker.
https://www.homedepot.com/p/Square-D-QO-20-Amp-Single-Pole-Circuit-Breaker-QO120CP/100028706

15 amp breaker
https://www.homedepot.com/p/Square-D-Homeline-15-Amp-Single-Pole-Circuit-Breaker-HOM115CP/100153952

20 amp breaker
https://www.ebay.com/p/GE-THQL-THQL1120-1-Pole-20-Amp-Circuit-Breaker/2254530853https://www.homedepot.com/p/Siemens-20-Amp-Single-Pole-Type-QP-Circuit-Breaker-Q120U/100044919


Did you find the breaker/space panel numbers for the 2 dedicated circuits for your audio system?

What to look for. In the majority cases the odd numbers are on the left side of the panel and the even numbers on the right side.

Example.
Single phase 120/240 Volt panel.
L = Line, Leg, Bus.


Left side ...........................................Right side

L1.. breaker/space #1) ........ breaker/space #2)

L2 .. breaker/space #3) ......... Breaker/space #4)

L1 .. #5) ............................................... #6)

L2 .. #7) ............................................... #8)

L1 .. #9) ............................................... #10)

L2 .. 11) ............................................... #12)

And so on down each side of the panel

jea48
2,944 posts
 
Posted by Ralph (M) on August 7, 2018 at 10:37:18

In Reply to: Is There A Reasoned Explanation Of Why Power Cords Work? posted by Mister Pig on August 2, 2018 at 10:21:38:


There are two aspects, AC voltage drop and high frequency current limiting.

AC voltage drop is the voltage dropped from the wall to the input of the equipment in use. I've measured a loss of 40 watts on an amp that makes 140 watts, so no-one should be surprised that that might be audible as well. I used a 3 1/2 digit DVM to measure the voltage drop and it showed around 3 volts. This was a pretty standard but inexpensive Belden cord. A more expensive Belden cord with heavier gauge showed a lessor drop and more power out of the amp. So no mystery here.

The second issue is the high frequency current limiting. This is a bit trickier to understand, but its not quite rocket science. Almost any power supply consists of a power transformer, rectifiers and filter capacitors. When the the transformer voltage is higher than the capacitor voltage, the rectifier commutates (a fancy word for turns on and conducts). At that point the filter capacitors can charge up and will do so until the power transformer voltage falls low enough that the rectifiers cut off.

At that point the circuit using the power supply drains the filter caps. Since this happens 60 times a second, the drain is usually not very much at all, so its only at the very peaks of the AC waveform that the caps are be replenished. There might be only a few microseconds or milliseconds that this can happen, and quite a bit of current might have to flow during that time, essentially a high frequency event.

If the power cord limits current during this period, the performance of the circuit using the power supply might suffer, possibly due to increased IMD since the DC might have a bit more of a sawtooth on it than if the current was not limited.

There are some take-aways; if the circuit is heavily regulated, the power cord will make less difference. If the connections at either end of the cord gets warm during operation, you can count on a voltage drop. How much the voltage drop in a power cord affects the audio performance depends on the AC wall voltage and the equipment itself.

A lot of people point out that there is wiring in the walls and from the power company and so on. Of course! But Romex is pretty high performance; if you could legally sell power cords made of Romex they would have excellent performance. But that would pose a fire and shock hazard so power cords are all about how to work with stranded wire.

One way to measure a power cord's performance is to measure the effect it has on the equipment in use. This is how I discovered that 40 watt loss I mentioned. If you have enough time and toys, you can set up a microphone in the room and measure frequency response and distortion rather than just testing the gear on the bench. I have a customer that used this technique to test filter capacitors in the power supplies of his amps.
https://www.audioasylum.com/audio/cables/messages/17/174988.html

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