The AM Forum
March 28, 2024, 12:20:03 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Two Wire v.s. Three Wire 120 VAC Shack Mains  (Read 8407 times)
0 Members and 1 Guest are viewing this topic.
W9ZSL
Contributing
Member
*
Offline Offline

Posts: 769


« on: September 28, 2016, 06:07:44 PM »

Problem.  I want to move the shack from the basement to upstairs.  The basement installation is ideal in that I ran new wiring from the service entrance to the gear via a three-wire line: hot / return / ground.  I grounded the gear to the incoming cold water pipe in the laundry room.  For health reasons, I need to move the station upstairs, but the outlets there are older two-wire types.  In addition, the only solid ground available is a hydronic hot water register next to the proposed station position. Could that be used as a station ground?  I can drive some ground rods down outside adjacent to the operation position and run the coax and ground through a hole in the outside wall.  Can I connect the rods with the register copper pipe? Would that work or should I just rely on the rods?  I'd have to use three wire to two wire adapters between the mains and gear of course.

Because of the position of the "new" station, running a new 120 V 3-wire power line is out of the question.
Logged
KA2DZT
Member

Offline Offline

Posts: 2192


« Reply #1 on: September 28, 2016, 07:47:10 PM »

What type wire is used inside the walls??  Romex?  BX? or what?
Logged
KJ4OLL
Contributing
Member
*
Offline Offline

Posts: 148


« Reply #2 on: September 28, 2016, 07:51:33 PM »

If it was my system, I would:
- Try to be sure of not creating any ground loops.
- Establish a new ground plate in the new room (I used a big piece of copper, drilled and tapped for bonding connections), bonded directly to the ground that the service panel uses.
- Ohm it out when finished
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #3 on: September 28, 2016, 08:20:32 PM »

The copper pipe hot water heating system should be fine for the SAFETY ground. You might want to check at the boiler and actually connect those pipes to an outside ground rod. The AC wires will power up your equipment. Hopefully you're not going to run a heavy load in your new radio room. Hopefully the house wiring should handle the load ok. If breakers start tripping; then you'll have to call an electrician to run new circuits to your room.

Your thought about running completely separate ground system from your room to a ground rod is acceptable too. It's the safety ground. This will not prevent RFI. RFI is from weird / bad antenna situations where there is an imbalance. Verticals and the lack of a good radial system is a good source of RFI. End fed antennas looking for a counterpoise or RF ground are another trouble maker.

If you're getting bit by RF; then you can get a nice tool from MFJ, where you actually tune a wire in the operating room to be that RF counterpoise and that might resolve any issues. MFJ 931, artificial ground.

KJ4OLL has good suggestions too

Logged

Fred KC4MOP
KD6VXI
Contributing
Member
*
Offline Offline

Posts: 2648


Making AM GREAT Again!


« Reply #4 on: September 28, 2016, 08:32:31 PM »

If you have gas water heater,  I'd run a bond from hot,  cold and gas,  at the water heater.   This ensures hot is always at cold and gas 'ground'  potential,  even if changing water heaters,  faucets,  etc.

It's a limited amount of times,  but there are times you could get a nasty bite.

Then,  at your service entrance panel (meter main),  make SURE gas and cold water is bonded to the ground rod system.

Any radio station ground rods should be connected to this ground at the entrance,  too.

Then,  your water heater 'ground'  will be safe for a 'safety ground'.

For a 100A main breaker,  ALL the connections mentioned above should be number 6, SOLID wire.   If you have a 120 to 200 amp main,  number 4 SOLID.

It's been found the added inductance of stranded can impede the rf impulse of lightening,  according to an inspector in Los Angeles County I had to deal with.

--Shane
KD6VXI
Logged
steve_qix
Contributing
Member
*
Offline Offline

Posts: 2599


Bap!


WWW
« Reply #5 on: September 28, 2016, 09:25:16 PM »

Problem.  I want to move the shack from the basement to upstairs.  The basement installation is ideal in that I ran new wiring from the service entrance to the gear via a three-wire line: hot / return / ground.  I grounded the gear to the incoming cold water pipe in the laundry room.  For health reasons, I need to move the station upstairs, but the outlets there are older two-wire types.  In addition, the only solid ground available is a hydronic hot water register next to the proposed station position. Could that be used as a station ground?  I can drive some ground rods down outside adjacent to the operation position and run the coax and ground through a hole in the outside wall.  Can I connect the rods with the register copper pipe? Would that work or should I just rely on the rods?  I'd have to use three wire to two wire adapters between the mains and gear of course.

Because of the position of the "new" station, running a new 120 V 3-wire power line is out of the question.

The other problem you might run into is the, like so many old houses, the wire in the wall may be inadequate (could be #14 or possibly smaller). I've definitely seen this.  And who knows about connections between your outlet(s) and the service panel.

If you can run some appropriately rated wiring on the outside of the building, you might want to run some 10-4 (H-H-N-G) and bring a 240V circuit up to a sub-panel, and fan out some good 20A 120V outlets with their own breakers.  Of course this also gives you 240V capabilities if you ever need that, too.

Then you would have a "real" ground run back to the S/E and much safer wiring all around.  Some of that old stuff is pretty underrated, and the connections between other outlets can be quite poor.

I did this in an old house back in the 70s.  That place had functional knob and tube among other old style bx cable.  Everything was underrated and dangerous, particularly when running a kW AM plate modulated transmitter off the stuff.  The "real" circuit I ran (on the outside of the house) was safe and properly rated.

Just a thought...
Logged

High Power, Broadcast Audio and Low Cost?  Check out the class E web site at: http://www.classeradio.org
kb3ouk
Member

Offline Offline

Posts: 1640

The Voice of Fulton County


« Reply #6 on: September 28, 2016, 09:49:18 PM »

Wouldn't happen to have any unused baseboard heaters in the area of the proposed shack, would you? My house was built in the late 40s and has two wire wiring everywhere, the upstairs bedrooms only have one outlet in each room, which is on a wall switch for a lamp, but every room has a few baseboard heaters which haven't been used for years that I have considered removing and putting outlets in boxes where the wires come up, then rewiring each circuit in the breaker box to be a 120 volt circuit instead of 240 like the heaters used. Another thing, I learned this when I replaced some of the outlets in the living room that were two wire, there are three things you can do if you have old two wire outlets and want to replace them, 1) replace with a new two wire outlet, 2) install GFI outlets like what you would have in your bathroom, 3) install a GFI breaker and then use regular 3 prong outlets, which is what I did because when my great-grandparents lived here they had several things that had 3 prong plugs plugged into 2 prong adapters to go in the outlets and the outlets had started to wear out and would not hold plugs in anymore, so I had to do something with them. The GFI breaker basically provides the same safety that the ground wire would, if something becomes unbalanced between the hot and the neutral wire, the breaker should trip.
Logged

Clarke's Second Law: The only way of discovering the limits of the possible is by venturing a little past them into the impossible
W9ZSL
Contributing
Member
*
Offline Offline

Posts: 769


« Reply #7 on: September 28, 2016, 10:23:12 PM »

The wire is Romex on a 15 amp circuit.  The basement is also a recording studio and everything is unbalanced but totally quiet.  Its ground bus comes from a copper pipe going up to the kitchen sink.  Never had a problem with ground loops even though the safety ground to the outlets is tied directly into the service bus.

The existing station ground comes from the pipe feeding the water heater.  It would be easy to re-route the ground from there to the living room and the new shack.  I'm mostly interested in keeping leads as short as possible.  The station will have a ground bus of course, but the common point is in question.  There is no possibility of connecting a safety to the service entrance directly like the basement shack is now.  For what it's worth, I have a breaker box with two branches for the studio.  I tapped the 240 volts and split it into a pair of 15 amp branches; one for the control room and one for the studio.  The station was connected to a 4-way, 3-wire outlet at the far end of the studio branch. Worked perfectly.
Logged
steve_qix
Contributing
Member
*
Offline Offline

Posts: 2599


Bap!


WWW
« Reply #8 on: September 28, 2016, 10:45:35 PM »

The wire is Romex on a 15 amp circuit.

Yeah, that suggests #14 wire.  Could have voltage drop issues also.
Logged

High Power, Broadcast Audio and Low Cost?  Check out the class E web site at: http://www.classeradio.org
W9ZSL
Contributing
Member
*
Offline Offline

Posts: 769


« Reply #9 on: September 28, 2016, 10:48:08 PM »

No doubt the old wiring is #14 however, the service panel was replaced around 1963 when the house was remodeled.  The baseboard heaters are hot water registers. That's why I thought I might be able to put a ground clamp on it because from the living room, the water circulates directly back to the furnace which is not more than 10 copper pipe feet away.  Come to think of it, I could simply put a strap between the return pipe and the existing ground pipe feeding the hot water heater and furnace.  
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« Reply #10 on: September 29, 2016, 12:27:35 AM »

Ground rods driven deep outside the radio room wall seem like a good idea. I don't like to connect grounds from equipment to water pipe because people say the small current will rot away the pipe eventually. Maybe a simple thing to do is install a lightningarrestor of the pass through type on the ground rod and hook the coax to it, then out to the antenna.

Is there a reason that a 3/4" hole can not be drilled from the basement up to the radio position right next to the wall and a surface duplex box mounted so that you have a couple of good 15A receptacles? This sort of thing can easily be undone later if the room absolutely has to be restored to original specification. Just saying, the mains ground is something I consider important for safety having been bitten a few times in the lab and a separate RF ground is important for the usual reasons.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
RolandSWL
Contributing
Member
*
Offline Offline

Posts: 253


« Reply #11 on: September 29, 2016, 09:02:42 AM »

I'm with those who suggest a proper, dedicated power line for the new location. Using a hydronic loop for the station ground is not a good idea as you probably have copper to iron pipe transitions that can lead to corrosion. Also, any r.f. in the heating loop can cause mischief with boiler controls.
Logged
W9ZSL
Contributing
Member
*
Offline Offline

Posts: 769


« Reply #12 on: September 29, 2016, 12:00:12 PM »

The bathroom and tub is on the other side of the wall from the new operation position so going through that wall is not possible.  I'll have to dig around a little.  It would be great to run wiring from the "studio" branch because there is little or no load on that line...just a fan which is used occasionally. I don't do sessions with musicians and their amps any more. I'll see if I can simply extend from the 4-way outlets where the equipment is plugged in now.  Another problem is there is no basement under the new op position.  If there was, it would be an easy job.
Logged
WBear2GCR
Member

Offline Offline

Posts: 4135


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #13 on: September 29, 2016, 03:47:16 PM »

Sounds like the room is on a slab or crawl space, first floor?

If so it becomes easier, perhaps.

One approach is to utilize a large 240:240 Isolation transformer in the shack.
Preferably it ought to have split secondaries (many do).
Then run the 240 up.
Take the secondary and ground that via the local ground rod/radial field outside the
xfmr location.

The trick here is to not hardwire it to the service panel.
Run it up as a plug in - a hubble twistloc at the panel is good. Or a 240vac dryer plug.

Once you plug it in, it skirts the electrical code, it's not permanent!

Also, technically it meets code for a "remote service", if you also have a service breaker panel too.

You still need to run the 240/4wire up.

Just another idea...

                         _-_-bear
Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
W9ZSL
Contributing
Member
*
Offline Offline

Posts: 769


« Reply #14 on: September 30, 2016, 05:40:18 PM »

Yeah Bear...crawl space.  Ain't going there even if I could.  The Kooks and Spideys would get me!  I DO think there is a solution. 

There is a junction box at the end of the "studio" branch and the "station" outlets come from there.  I must have planned on expanding beyond that point because I installed a cable clamp in the box.  If I run a cable from there under the bathroom to an area under the vanity, and drill a hole inside that cabinet, it abuts against the living room wall.  I can drill through the cabinet and wall and then install surface mount outlets in the corner to service both the computer and the station.  Nothing else is on the circuit which is 15 Amps.  Add some ground rods and that should do it.

Wife (Da Boss) gave me the OK.  Will keep you posted.
Logged
KD6VXI
Contributing
Member
*
Offline Offline

Posts: 2648


Making AM GREAT Again!


« Reply #15 on: September 30, 2016, 08:16:56 PM »

Keep in mind the need for all ground rods to be bonded to the main entrance panel with #6 gauge solid copper up to a 200A main breaker.   At that size,  you need to run #4 solid to each ground rod.

That can be negated if using an isolation xformer.  However,  on the isolation xformer side,  you'd also need a subpanel, as ground wouldn't necessarily trip.   I'd have,  at a minimum,  a GFCI on the new isolated circuit.   

--Shane
KD6VXI
Logged
WB2RJR
Member

Offline Offline

Posts: 400


1st BCT, 10th Mountain, returned from Iraq 11/2008


« Reply #16 on: October 16, 2016, 05:44:39 PM »

It seems to me Romex has a ground wire which grounds the metal part of the outlet even though it is a two two hole outlet. That's how those three to two plug adapters work, there is a center spade that is supposed to be screwed onto the outlets center plate, which is grounded.

Check it out it may save some time.

73, Marty

P.S. This means all you have to do is put in a new three prong outlet and throw the two prong away.
Logged

AMI #20, GACW #786
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.062 seconds with 19 queries.