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Author Topic: How many amps for ham station?  (Read 1563 times)
K6JH
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Posts: 41




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« Reply #15 on: Yesterday at 03:16:09 PM »

I don't think you are permitted to have a separate ground on the sub-panel unless it is bonded back to the main panel ground. We had two buildings that were fed from different pole transformers and they still make us bond the two building grounds together.



So what's the difference between two buildings fed off different transformers, and 2 separate homes? 2 adjacent homes don't have to be bonded. Now I suppose if you had other wiring going back and forth (CATV, phone, etc) between buildings - but that's different.

In my case I'm feeding the detached garage from my house service entrance panel - so I get that. That was part of the problem - the quoting electrician (actually my wife did this without asking me!) said that the garage could be grounded separately. And I didn't believe him!

The other thing I've thought of is to have two operating positions - a "primary" position in the detached building for contesting etc, and a "secondary" position in the house. Maybe with a fat run of heliax between them. But my understanding is I still have to bond the two positions together and to the service entrance. So that complicates things even more.
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N9DG
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Posts: 313




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« Reply #16 on: Yesterday at 05:00:50 PM »

As usual you are wrong. NEC requires the 2 pole on new installations. Period. Learn before you comment.

Even with the appropriate 2-pole breaker as spelled out by the NEC I still would not go this route. If you ever have break in the neutral wire between the panel and these outlets you then better hope that the resistance (we'll ignore any impedance for simplicity sake) of the loads on the two sides are equal. Because without the neutral the two circuits are then a series circuit, so the equipment on one outlet may be subjected to an over voltage, while the opposite side outlets would be under.

With dedicated hot/neutral pair for each circuit, any of the wires could fail and nothing would be subjected to an over voltage. Just spend the few extra $'s for a couple more neutral wires.
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N9DG
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Posts: 313




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« Reply #17 on: Yesterday at 05:42:52 PM »

I don't think you are permitted to have a separate ground on the sub-panel unless it is bonded back to the main panel ground. We had two buildings that were fed from different pole transformers and they still make us bond the two building grounds together.


So what's the difference between two buildings fed off different transformers, and 2 separate homes? 2 adjacent homes don't have to be bonded. Now I suppose if you had other wiring going back and forth (CATV, phone, etc) between buildings - but that's different.

In my case I'm feeding the detached garage from my house service entrance panel - so I get that. That was part of the problem - the quoting electrician (actually my wife did this without asking me!) said that the garage could be grounded separately. And I didn't believe him!

In NEC 2005 it was still permissible to have a separately grounded sub-panel in a detached building like a garage IF there were NO other conductive paths between the two buildings (phone lines, coax cables, metal water lines, etc.). In NEC 2008 it was changed that the sub panel in the second building in addition to having its own ground rod(s) must also be bonded to the main panel with a ground wire (4 wire system). I'd be surprised if there are many jurisdictions left anywhere that are still using NEC 2005 as their basis. So I'd get another quote from another electrician  Wink..

The other thing I've thought of is to have two operating positions - a "primary" position in the detached building for contesting etc, and a "secondary" position in the house. Maybe with a fat run of heliax between them. But my understanding is I still have to bond the two positions together and to the service entrance. So that complicates things even more.

Presumably the two stations would share or swap antennas, or have an interconnect feedline(s) as you noted.. For that reason alone I would want to bond the grounding systems together between both locations, this is true whether even if they are fed by separate electrical services or not. It has as much to do with the lightning protection aspects of the whole system as it does AC power system safety.
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AA4PB
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Posts: 12698




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« Reply #18 on: Yesterday at 06:07:31 PM »

"So what's the difference between two buildings fed off different transformers, and 2 separate homes?"

The two buildings have CATV, phones, and alarm wiring running between them. I expect that the bonding would have been required anyway because the two buildings are next to each other, on the same property, and had the same owner so the inspector would assume that other wiring might be added between them in the future.

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KD8MJR
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Posts: 2082




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« Reply #19 on: Today at 02:00:44 PM »

What would be nice is a 50 amp 240v sub panel inside the shack the split 2 20 amp 120v circuits and one 30 amp 240 circuit.
Greg

You will never use over even 10k. This 50amp thing must be another ego thing. Two separate 15 or 20amp circuits for 120 and a 20 for 240is more than enough.

I have to say that for once "Gulp!" I agree with W8JX.
A separate 50amp 240V panel is just overkill.  I have 10A 120V breaker from the house panel that feeds my Radios and tons of other equipment and I have a 20amp 240V Breaker that feeds my 1500W amp and the rooms split AC system.  I have never had a problem even during 10 hour runs during contests.


The downside with going too big with the breaker and wiring is that it's going to take one hell of an incident to trip that 30Amp 240V breaker, it's better to keep the breaker a bit closer to the normal load and not going insanely overboard.
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W9FIB
Member

Posts: 586




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« Reply #20 on: Today at 02:49:05 PM »

What would be nice is a 50 amp 240v sub panel inside the shack the split 2 20 amp 120v circuits and one 30 amp 240 circuit.
Greg

You will never use over even 10k. This 50amp thing must be another ego thing. Two separate 15 or 20amp circuits for 120 and a 20 for 240is more than enough.

I have to say that for once "Gulp!" I agree with W8JX.
A separate 50amp 240V panel is just overkill.  I have 10A 120V breaker from the house panel that feeds my Radios and tons of other equipment and I have a 20amp 240V Breaker that feeds my 1500W amp and the rooms split AC system.  I have never had a problem even during 10 hour runs during contests.


The downside with going too big with the breaker and wiring is that it's going to take one hell of an incident to trip that 30Amp 240V breaker, it's better to keep the breaker a bit closer to the normal load and not going insanely overboard.

I used to think that too. Then I did some pricing when I ran out of outlets and found in the long run as you add things, it is lower cost overall to have had a sub panel during the new construction then to keep making new runs back to the main panel.

Then there is the convenience factor. I like when my breakers are right where I have a higher possibility of tripping them is really handy. Running to the breaker panel after tripping out all my outlets because I used the multi-wire method just seems silly. (I would have it wired correctly, not like JX.) And just that alone was worth the extra $50. And saved me hundreds the 2 times I needed to add a new circuit.

It also really isn't about how much power you use. It is more about circuit distribution. 200A is overkill for most houses because how many times do you draw even close to that? Same with a sub panel where you will distribute several loads. The total capacity you may use may be less or even much less then what you use. But with outlets on multiple circuits, there is less that will die when a breaker does trip. Another convenience factor.

Besides you don't run your amp at 287 watts when that's all that is needed when you have a KW. That is overkill too. So by that way of thinking there would be little market for legal limit amps. But they sell 'em all the time. So why is making electrical service more convenient any more of an overkill?
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