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Yaesu FT-747GX »
« Impedance 101: A Refresher on Transmission Lines & Cable Ind  
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Splitpair
Premium
join:2000-07-29
Cow Towne
·T-Mobile US
·T-Mobile US
·AT&T Southeast


edit:
November 22nd, @04:11AM

reply to burner50
Re: The Science of Effective Grounding...

said by burner50 See Profile :

When i put up an aerial mast I was planning on digging an 18 inch trench and sinking in Four 8' rods 18 inches apart and welding 8 gauge copper to them.
Generally speaking your ground rods should not be closer to each other than the length of the rod. So with 8 foot rods 10 foot spacing would be fine.

If you are a really anal such as I am you will place a new ground rod at each service (power Telco cable satellite and antennas) in addition to a ground rod at each corner of the building. Those rods are bonded by a bare buried copper wire to form as close to a ring as possible to avoid dead-end-points.

Your minimum wire gauge for grounding and bonding should be #6 bare copper with all connections exothermically welded.

ALL building grounds shall be bonded together to prevent any possibility of a ground potential difference between grounds. Failing to do so is like begging ole mother nature to destroy your electronics.

A common grounding point should be established in the hut/shack and all cables as well as equipment shall be grounded to this point before connection to equipment.

When building your common grounding point don’t forget to insulate it from the wall to prevent any secondary paths to ground.

Where not placed by the service provider place primary surge protectors as close as possible to where the service enters the building but if possible always external to the building to minimize the chance of fire should a hard cross with power cause a catastrophic failure of the surge protector.

Don’t fail to include in the above an entire-home surge protector for the power entering the home. Be sure that protector provides hot to hot, hot to neutral and all lines to ground protection.

Contrary to common belief underground service is not immune to surges and lighting hits. The reality is at least around here that equipment connected to underground residential distribution (URD) is more susceptible to being damaged as FP&L’s engineers have decided that URD transformers don’t require primary surge protection as the primary is buried which is true. However they install streetlights which do get hit and carry that hit to the secondary which is in parallel to the service feeding the homes connected to the URD system.

At least in aerial residential distribution (ARD) the primary acts as a static line taking the hit and passing it to ground via. the primary surge protectors on the ARD transformers. Us folks on URD do not have that luxury.

I am currently (pardon the pun) in the process of re-writing this FAQ »AT&T Southeast Forum FAQ »How can I protect my DSL/dialup equipment from surges? to make it more relevant to Ham radio and will submit for inclusion to the FAQ’s here once completed. In the mean time I have included a couple PDF attachments from my employer on grounding and bonding. Just a little light reading to keep ya busy for now.

Wayne
--
If you cannot fix it with a buttset and some beanies you ain't a technician.


KA3SGM
- -... ...- -
Premium
join:2006-01-17
West Chester, PA
clubs:
·Verizon FIOS

said by Splitpair See Profile :

said by burner50 See Profile :

When i put up an aerial mast I was planning on digging an 18 inch trench and sinking in Four 8' rods 18 inches apart and welding 8 gauge copper to them.
Generally speaking your ground rods should not be closer to each other than the length of the rod. So with 8 foot rods 10 foot spacing would be fine.

If you are a really anal such as I am you will place a new ground rod at each service (power Telco cable satellite and antennas) in addition to a ground rod at each corner of the building. Those rods are bonded by a bare buried copper wire to form as close to a ring as possible to avoid dead-end-points.

Your minimum wire gauge for grounding and bonding should be #6 bare copper with all connections exothermically welded.

ALL building grounds shall be bonded together to prevent any possibility of a ground potential difference between grounds. Failing to do so is like begging ole mother nature to destroy your electronics.

A common grounding point should be established in the hut/shack and all cables as well as equipment shall be grounded to this point before connection to equipment.

When building your common grounding point don’t forget to insulate it from the wall to prevent any secondary paths to ground.

Where not placed by the service provider place primary surge protectors as close as possible to where the service enters the building but if possible always external to the building to minimize the chance of fire should a hard cross with power cause a catastrophic failure of the surge protector.

Don’t fail to include in the above an entire-home surge protector for the power entering the home. Be sure that protector provides hot to hot, hot to neutral and all lines to ground protection.

Contrary to common belief underground service is not immune to surges and lighting hits. The reality is at least around here that equipment connected to underground residential distribution (URD) is more susceptible to being damaged as FP&L’s engineers have decided that URD transformers don’t require primary surge protection as the primary is buried which is true. However they install streetlights which do get hit and carry that hit to the secondary which is in parallel to the service feeding the homes connected to the URD system.

At least in aerial residential distribution (ARD) the primary acts as a static line taking the hit and passing it to ground via. the primary surge protectors on the ARD transformers. Us folks on URD do not have that luxury.

I am currently (pardon the pun) in the process of re-writing this FAQ »AT&T Southeast Forum FAQ »How can I protect my DSL/dialup equipment from surges? to make it more relevant to Ham radio and will submit for inclusion to the FAQ’s here once completed. In the mean time I have included a couple PDF attachments from my employer on grounding and bonding. Just a little light reading to keep ya busy for now.

Wayne
AMEN Brother...Thanks !!
--
"Lithium is no longer available on credit"


Splitpair
Premium
join:2000-07-29
Cow Towne
·T-Mobile US
·T-Mobile US
·AT&T Southeast

reply to Splitpair
Re: The Science of Effective Grounding... A few more links

»www.eeel.nist.gov/817/pubs/spd-a···uide.pdf

»www.eeel.nist.gov/817/pubs/spd-a···ning.pdf

»www.nist.gov/public_affairs/prac···sfnl.pdf

»www.eeel.nist.gov/817/pubs/spd-a···link.pdf

Wayne
--
If you cannot fix it with a buttset and some beanies you ain't a technician.


dandeman

join:2001-12-05
Chapel Hill, NC
·AT&T Southeast


edit:
December 2nd, @12:17PM

Good reading.. especially links 2 and 4 above..

Both point out a concept I feel strongly about..

That is, even with whole house protection at the service entrance and applicable surge suppressors on phone, cable, etc there tied to common ground... as distance to electronic devices throughout the house increases, there is an increasing need for "surge reference equalizers" (to use their terminology) to be installed AT THE LOCATION of any equipment having multiple paths (e.g. power and telephone line/cable, etc).

As the distance to the equipment grows and the enclosed area in the loop formed by the multiple paths to a piece of equipment grow larger (borrowing from Ampere's Circuital Law for any so interested) otherwise in simple terms, the loop works like a 1 turn transformer winding... the magnetic field from any nearby 18kA statistcal average lightning hit makes use of this one turn transformer winding quite effectively and to the detriment of the equipment at the end of the loop. Without an SRE, the connected equipment closing the loop, becomes the fuse in series with the loop. With the SRE, it closes the loop ahead of the equipment leaving the equipment on a short protected stub.

The distributed SREs in turn pretty much mandates a perimeter or some other pretty solid bonding system to ground the distributed systems together.

Not a new idea, see it fairly often in commercial installations. This concept was a major consideration in designing my system pictured in the previous post..
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« Impedance 101: A Refresher on Transmission Lines & Cable Ind  


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