Can sombody please help with this

[martinh89]

Please could somebody shed some light on this for me.My dad is an amateur radio enthusiast and over the years has built up a decent size bit of kit, he has a dc grounded earthed aerial that connects to the back of his radio , which has a power supply (class1 equipment) plugged into the ring main.my question is how do I go about bonding it to the MET.My thoughts were to take a 10mm earth cable from the MET to an earth rod , then bond all the exposed metal parts of the raido equipment to a common earth bar , then another 10mm cable from the common earth bar to the earth rod.Can somebody pleas advise me on this thanks

 

[davesparks]

This may be a daft question, but why does it need bonding?

 

[Marvo]

If the radio is classI LV (230VAC) then it would be grounded by the CPC of the ring circuit it's plugged into. If the radio is fed 12V DC for example from a separate power supply then it may be completely isolated and not require a separate earth.

There's numerous reasons you'd ground a radio set which might include lightning protection, antenna groundplaning and standard saftey earthing as per ClassI requirements. Wthout precise details of your setup it's difficult to advise further.

 

[martinh89]

This may be a daft question, but why does it need bonding?

because the dc earthed aerial will be at a different potential to the house ring main (witch the power supply is connected too) so under fault conditions there will be a potential difference at which my dad could receive a shock

 

[tazz]

For lightning reasons, you dont bond or earth any of the radio equipment, due to the fact, that this will be the path it follows.....most aerials have a lighting bolt at the bottom of the mast, this is to be tied down to earth via a rod. Idea here is the will then be the quickest path to earth, and not through the radio equipment.

 

[martinh89]

For lightning reasons, you dont bond or earth any of the radio equipment, due to the fact, that this will be the path it follows.....most aerials have a lighting bolt at the bottom of the mast, this is to be tied down to earth via a rod. Idea here is the will then be the quickest path to earth, and not through the radio equipment.

yes but my question stems from that the dc grounded aerial comes to the back of the radio and ends there. The power supply is 12v class 1 equipment plugged straight into the mains, because in affect theres 2 earths (not bonded) wouldn't there be a rise in potential under fault conditions

 

[tazz]

only on the power supply....the radio is 12v dc, All masts i have erected, have been earth straight at the bottom of the mast, direct path to earth

 

[Buckfast]

As Tazz has stated above the PSU may be Class 1 but the radio is 12V DC. I would of expected the 12V DC supply to be derived from a double wound transformer followed by regulation inside the 12V PSU. I would not expect any connection between the -ve and mains cpc conductor. No bonding required.