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Author Topic: Confused about grounding  (Read 7717 times)
KK6GMN
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Posts: 150




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« on: September 11, 2013, 04:54:17 PM »

I am setting up my first station (base) and am a little confused about grounding the equipment. The more I read the more confused I seem to get.

If I have an antenna in my attic, no grounding other then what is supplied by the coax connector to the radio is required for the antenna part, correct?

If I plug my power supply into a tested and well grounded 3 prong socket and then ground the rig and other equipment to that, am I all set? 

I know I can go directly to the grounding on my power panel outside, but if I do that and am plugged into a ground plug for the power supply, have I not created a ground loop?

What am I missing here? 

Now, once I have an antenna outside, I understand I need a path for the metal mast to ground (on the service panel) and a path from the coax, before it enters the house, to the ground.  It looks like I should then connect my internal grounded equipment to that external ground, but my power supply is also grounded through the plug... still a ground loop?

Hmmmm... It almost seems that the PS should not be in a grounded plug, but that does not sound safe...... Thanks for the help and guidance.
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-SeanM
KK6GMN

"No man is a failure...
...who has friends." --Clarence

Weather at my shack
http://www.pegnsean.net/~sean/weather/wx.htm
AA4PB
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« Reply #1 on: September 11, 2013, 05:44:42 PM »

There are three primary uses for grounds:

1) RF ground. Some antennas like a 1/4 vertical or end-fed require an RF ground such as radials or a counterpoise in order to provide a complete path for current flow. Other antennas such as a dipole are complete by themselves and require no RF ground.

2) Electrical safety ground. That's the third wire on your power supply. If something shorts to the case in the power supply this provides a path back to the breaker panel so that the fault current trips the breaker.

3) Lightning protection ground. This is an Earth ground normally connected to the coax shield(s) just outside the house entrance. Its purpose is to divert the majority of lightning current away from the house in the event of a nearby strike that couples energy into the antenna and/or coax shield. If your antenna is in the attic (already inside the house) there is not normally much benefit to a lightning ground. In most indoor antenna installations there is not a good way to make a short run to an Earth ground. One exception may be a commercial building where you can bond it to building steel.

The National Electric Code (NEC) requires that all antenna system grounds and the electrical system ground be bonded (permanently connected) together with at least a #6 copper wire. This is primarily to protect you from shock by ensuring that all grounds are maintained at the same voltage reference.
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M6GOM
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« Reply #2 on: September 12, 2013, 03:17:15 AM »


Now, once I have an antenna outside, I understand I need a path for the metal mast to ground (on the service panel) and a path from the coax, before it enters the house, to the ground. 

No need to and if doing so sorts a problem you need to re-look at your antennas. You may want to put lightning protection in depending on where you live but an antenna shouldn't need the coax grounding nor the metal mast.
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N1UK
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« Reply #3 on: September 14, 2013, 05:16:49 PM »

A ground loop is an issue for audio (AF). It is not an issue for RF. Multiple paths for RF and lightning protection can be good.


You could install a ground rod by your station. For rf, the connection to this station ground rod should be less than 10 feet. You should connect this ground rod to your utility ground rod using a minimum of #6 wire which is run outside the house.


How good is your utility ground?

Mark N1UK
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KK6GMN
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« Reply #4 on: September 14, 2013, 10:26:29 PM »

Thanks for the advice!!

Not great and the house is surrounded with concrete.  No place for a rod unless I drill and there may be unknown pipes down there for pool, gas, sprinklers. All utils are undergrounded here, no poles except streetlights.  The main power panel does not even appear to have a ground. It must be, but it is probably under the foundation and in the wall someplace since it is concrete all around.  I am entering the house on the second story.  It is about 20-25' to my electric panel from the entry point and the ground for the satellite dish is attached to a screw clamp connector external top of the power panel.  I was going to run my station ground and antenna wire ground to that from the window where the antenna lines come in.  I was also going to place grounding rods at the two places where I plan to have my antenna masts grounded.  They are away from the house by about 20'  and have access to dirt... so how does that sound?

Now I have also read that some folks do not ground at all, and honestly while I am testing my rig and antenna, I am not grounded at all yet. (gulp) 
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-SeanM
KK6GMN

"No man is a failure...
...who has friends." --Clarence

Weather at my shack
http://www.pegnsean.net/~sean/weather/wx.htm
N1UK
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« Reply #5 on: September 15, 2013, 05:03:29 PM »

Yes all that concrete makes it difficult.  My load center grounding was some iron water pipe banged into the ground in 1974 or so. Goodness knows how good it was. I added a second 10 foot copper rod next to it.

I went overboard with my tower. I ran #6 solid bare copper wire around the house with ground rods every 16 feet. I also have two 80 foot runs of copper and ground rods which run away from the tower.

The station has about 4 ground rods as well. All are tied together and tied to the load center ground.


Mark N1UK
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K1PJR
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« Reply #6 on: September 18, 2013, 08:12:39 PM »

Sean

Do a search under the articles here at Eham by Steve Katz. He talks about the misconceptions regarding grounding. Very good perspective. BTW I do not ground my equipment or antenna. I have zero issues. I disconnect my antenna when not in use. Read the article and you will have a better understanding about to ground or not to ground.

73
Phil
K1PJR
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KK6GMN
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« Reply #7 on: September 19, 2013, 09:43:28 AM »

Thanks Phil.  That article by Steve is one of the ones that confused me.  All the other reading I do is very detailed about the need for grounding, and Steve is just the opposite.

There are code requirements for grounding as well, so I am sort of in a quandary.  I am sure I will find a way.  I want to balance safety and sanity.  I for sure do not want to make things worse.
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-SeanM
KK6GMN

"No man is a failure...
...who has friends." --Clarence

Weather at my shack
http://www.pegnsean.net/~sean/weather/wx.htm
K0ZN
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« Reply #8 on: September 20, 2013, 10:12:59 AM »

Hi.

You are over thinking it.  If you live in an area with rare or very little lightning, then your primary need is safety and maybe static drain. Bond all equipment together with decent sized wire. Run a # 6 wire to the electrical power ground/panel. If you can, drive an additional ground rod and connect that to the power ground.

NEVER leave an antenna "floating". i.e. not connected to anything. If you disconnect it, Ground it !

If you do have lightning concerns, then you need to dig and research a little more. A lightning strike can catastrophic to your equipment and home. You have to decide
how much risk that is and if you want to reduce or eliminate that risk.

It comes down to how much are you willing to bet that there NEVER, EVER will be a failure or hazard on your AC power distribution line/system/wiring or failure of insulation somewhere in your equipment and what are the odds of a direct (or near by) lightning strike to your antenna or house or neighbors lines/house. Ultimately, it is your call.....

73,  K0ZN
« Last Edit: September 20, 2013, 10:19:02 AM by K0ZN » Logged
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