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Author Topic: New Amp and 240 volt Line  (Read 1934 times)
W3DDF
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Posts: 76




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« on: February 21, 2013, 10:45:20 AM »

I am purchasing a Tokyo Hy Power HL-1.5k amplifier.  The manual says that it draws 10 amps max on 240 volt.  What size breaker should I install?  I was first thinking about 20 amp in case I obtain another amplifer in the future or go with a 15 amp to be on the safe side.
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AA4PB
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« Reply #1 on: February 21, 2013, 10:56:39 AM »

The breaker is not there to protect the amp, it is to protect the wiring. The amp has its own breaker or fuse to protect it. I'd definitely use a 20A breaker with #12 conductors.
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W8JX
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« Reply #2 on: February 21, 2013, 11:02:20 AM »

I am purchasing a Tokyo Hy Power HL-1.5k amplifier.  The manual says that it draws 10 amps max on 240 volt.  What size breaker should I install?  I was first thinking about 20 amp in case I obtain another amplifer in the future or go with a 15 amp to be on the safe side.

I run my old Dentron with 4  572's on a 15 amp 240v circuit. It will make 1300+ but normally run about a 1000 or less. You need to remember that a 15 amp breaker does not blow at 15 amps but usually 10 to 25% above that. A 15 amp 240 v circuit can deliver 3600 watts which is more than enough for legal limit. If you need more it is because you plan on running above legal limit. 

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KE3WD
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« Reply #3 on: February 21, 2013, 11:50:59 AM »

The breaker is not there to protect the amp, it is to protect the wiring. The amp has its own breaker or fuse to protect it. I'd definitely use a 20A breaker with #12 conductors.


There ya go. 


73
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AD4U
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Posts: 2164




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« Reply #4 on: February 21, 2013, 12:08:45 PM »

What ever you decide:

#14 wire - 15 amp breaker (or smaller)
#12 wire - 20 amp breaker (or smaller)
#10 wire - 30 amp breaker (or smaller)

Even #14 wire (assuming a reasonable distance from the box to the recepticle) will "run" a 1500 watt output amp.  Assuming 50% amp efficiency (including filament current and fan current) you will be drawing no moe than 3000 watts from the AC line

3000 watts / 240 volts = 12.5 amps.  Since #14 wire will "handle" 15 amps continuous duty and since SSB and CW are not continuous duty modes, #14 wire will be OK.

If it were me and considering the small additional cost, I would opt for #12 or even #10 wire.  Either will have less voltage drop than #14.  As your shack "grows" you won't be sorry if you install the larger wire.

Dick AD4U
« Last Edit: February 21, 2013, 12:16:07 PM by AD4U » Logged
W8JX
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Posts: 5768




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« Reply #5 on: February 21, 2013, 12:10:54 PM »

The breaker is not there to protect the amp, it is to protect the wiring. The amp has its own breaker or fuse to protect it. I'd definitely use a 20A breaker with #12 conductors.


There ya go. 


73


Nothing gained with a bigger breaker than needed. While I agree that breakers protect wiring they do protect devices too. For maximum safety never use a breaker bigger than needed for load. You can use 12ga wire if you want with a 15 amp breaker.
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AA4PB
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« Reply #6 on: February 21, 2013, 12:21:46 PM »

If the amp is spec'd at 10A then it probably has a 10 fuse in it. The fuse will blow before a 15A breaker trips. The breaker is there to protect the wiring in the house (15A for #14 wire and 20A for #12 wire) so put in a 20A breaker and have enough power for a larger amp in the future. The fuse in the amp will protect the amp in the event of an internal short.

Most modern homes use 20A breakers on all of the general purpose circuits. That doesn't mean that you have to have a 20A load on each circuit. The breaker isn't there to protect the load.
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K6AER
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« Reply #7 on: February 21, 2013, 03:49:58 PM »

Given a transistor, fuse and a breaker to exceed their load requirements the breaker will trip last. The transistor will protect the fuse.

Always use the correct size wire for the breaker combitination, it is a NEC requirement and causes less confusion on down the road when the next home owner cannot see the wire you have installed.
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KE4DRN
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« Reply #8 on: February 21, 2013, 04:43:01 PM »

Hi

how many feet from the panel (or sub panel) will the amp be located?

73 james
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W3DDF
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Posts: 76




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« Reply #9 on: February 21, 2013, 05:42:56 PM »

The amplifier will be approximately 40 feet away.  I ran 12/2 wire and planning to use a 20 amp breaker.
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AD4U
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« Reply #10 on: February 22, 2013, 05:33:15 AM »

The amplifier will be approximately 40 feet away.  I ran 12/2 wire and planning to use a 20 amp breaker.

12/2 W/G will work just fine.

Dick  AD4U
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AA4HA
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Posts: 1434




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« Reply #11 on: February 22, 2013, 08:03:02 AM »

With all things being equal. Assume that the 40' drop will require 50' of wiring

50' run, 15A at 240 volts;

#10 AWG   drop 1.54V   load 238.46V   drop 0.6%
#12 AWG   drop 2.45V   load 237.55V   drop 1.0%
#14 AWG   drop 3.90V   load 239.10V   drop 1.6%

50' run, 20A at 240 volts;

#10 AWG   drop 2.05V   load 237.95V   drop 0.86%
#12 AWG   drop 3.27V   load 236.74V   drop 1.36%
#14 AWG   drop 5.19V   load 234.81V   drop 2.16% *not to code*

50' run, 25A at 240 volts;

#10 AWG   drop 2.57V   load 237.43V   drop 1.07%
#12 AWG   drop 4.08V   load 235.92V   drop 1.70% *not to code*
#14 AWG   drop 6.48V   load 233.52V   drop 2.70% *not to code*

50' run, 30A at 240 volts;

#10 AWG   drop 3.08V   load 236.92V   drop 1.28%
#12 AWG   drop 4.90V   load 235.10V   drop 2.04% *not to code*
#14 AWG   drop 7.78V   load 232.22V   drop 3.24% *not to code*

It is all ohms law. (do not drive while being a resistor). An online calculator can be found at;

http://www.powerstream.com/Wire_Size.htm
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
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