kymanor118 posts
03-05-2020
9:23pm
We all know the benefits of dedicated lines, so what is this all about?
Best practices....
Hopefully to better understand the type of branch circuit wiring used and the best method used for installing it.
Jim.
Lets talk dedicated lines
About a year ago I installed a dedicated 20 amp line for my system...and went as far as modding the whole power structure from the street transformer to my panel to my house...at some fairly major expense. The result was certainly an improvement for my system.
Recently i got to thinking that a lot of us have a system that utilizes the standard 15amp line that more than likely only supplies one other component in our rooms...and that is the lights. While lights can be noisy on the system, particularly if they are halogens, then this is a source of considerable hash and noise. However, since the only other thing shared by this line are the lights...and not the more power hungry grabbing stuff..like the refrigerator, or the Ac etc, then simply playing the system in the dark should essentially allow for a dedicated line effect to materialize on the gear that is attached to this line as well. The standard room convenience outlet( which is what we are talking about here) is 15 amp breaker protected and is only supplying the lights and the convenience outlet in a room....so ( assuming that this is the case--and the lights are the only thing supplied besides the outlet) what is the real advantage to the 'true' dedicated line ? Twenty amps is more than a lot of auto gear needs, so I doubt that is the issue...thoughts?
Recently i got to thinking that a lot of us have a system that utilizes the standard 15amp line that more than likely only supplies one other component in our rooms...and that is the lights. While lights can be noisy on the system, particularly if they are halogens, then this is a source of considerable hash and noise. However, since the only other thing shared by this line are the lights...and not the more power hungry grabbing stuff..like the refrigerator, or the Ac etc, then simply playing the system in the dark should essentially allow for a dedicated line effect to materialize on the gear that is attached to this line as well. The standard room convenience outlet( which is what we are talking about here) is 15 amp breaker protected and is only supplying the lights and the convenience outlet in a room....so ( assuming that this is the case--and the lights are the only thing supplied besides the outlet) what is the real advantage to the 'true' dedicated line ? Twenty amps is more than a lot of auto gear needs, so I doubt that is the issue...thoughts?
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- 31 posts total
You make some good points, but you are mistaken about lights and outlets being on the same circuit (breaker), unless your house was built before the 1960's (or against code). I use a dedicated 30 amp line to power my system, and it works great. For those of you who want to test a dedicated circuit of 20 amps, at least before shelling out a lot of money for electricians, etc., get a good 20 amp extension cord and run it from a dining room, kitchen, or preferably from a dedicated clothes washer outlet to your system. BTW, a 15 amp circuit uses 14 gauge wire, 20 amps 12 gauge, and 30 amp 10 gauge. Breakers blow at 75% of their rated amperage. Thus, my two 1500 watt draw Audire amps alone, need the 30 amp breaker, despite their regulated power supplies; that plus two preamps, three tuners, a CD player, and turntable. |
RE: The comment about 240 volts and a step down transformer. I ran 10 gauge wiring from a 30 amp 240 volt breaker, then split pairs of 110 volt outlets to run half my system on each leg, giving 120 volts per leg, and 30 amps of current. It is a lot cheaper, but if I sell my house, I will dismantle the circuit to protect the innocent. |
@ danvignau Here is an older white paper for a circuit breaker. The trip curve/requirements for current manufactured Thermal-Magnetic (T-M) breaker are still the same. Note you can continuously load a T-M breaker to 100% of its’ handle rating and it will not trip if it is operating at its’ designed specs. (Continuous is defined as three hours or more). https://goodsonengineering.com/wp-content/uploads/2017/08/CircuitBreakerMyths_web.pdf Jim. |
AC power is a funny bugger and it helps to understand how “noise” gets onto the line. Basically noise are tiny “spikes” imprinted onto the sinusoidal AC wave from various sources. Use of a scope can show this. I have a Flintstone era Tektronix tube scope which I use and shows this clearly. Some of the worst offenders in residential are motors (with brushes such as vacuum cleaners), compact fluorescent lamps (the self-contained pigtail type which can cause over 100% harmonic distortion on the neutral) and any electronic device which requires a large inrush current. Also remember that most “noise” is running on the utility lines themselves due to harmonics imparted from various sources mostly large motors. A dedicated line may help and the use of hospital grade aluminum clad MC cable may help due to the sheath acting as a shield against RF. IG hospital grade MC cable uses a second ground (green with yellow stripe) and with the use of an IG receptacle may eliminate some noise off of the line. This is used for sensitive hospital equipment located in ER’s, ICU’s, CCU’s etc. The extra ground wire is connected to a separate isolated bus bar inside of the electrical panel which is then connected to the ground bus. A residential whole house TVSS (transient voltage surge suppressor) will eliminate some noise, protect sensitive electronic equipment, not costly, easy to install and only requires two spare circuit breaker spaces and a dedicated twenty ampere two pole CB in an electrical panel. An isolation transformer (1:1 ratio) connected to your equipment may also help on a dedicated line by isolating both the hot and neutral lines from the utility but the ground will not necessarily be isolated. An isolation transformer is rated in Volt Amps (not watts) and multiplying the voltage times the required amperage will give a good estimate of the size needed (120v x20A=2.4kVA) but will not take into account the small losses due to coil efficiency (power factor). Unless your equipment requires it and you have an extreme case, I cannot see why anything larger that a 20 ampere 120 -volt dedicated line would be necessary using the above methods. Of course some experimentation will be needed to get it to satisfaction. Remember that most equipment and utility grids are 60 to 80 years old and modern upgrades to generating, transmission and distribution have not taken place mostly due to exorbitant cost. Utilities are required to provide power but not necessarily clean power. (My background is an EE degree from PSU some 40 years ago, am a licensed electrician and worked with many local hospitals and utilities in design build). Hopefully this will shed some light on power line carrier noise. |
- 31 posts total