Horizontal long wire MW aerial.

[Murphyv310]

Hi Mike. TBH I only use 2.5mm cable from my earth rods. Again there is a lot of discussion in amateur circles regarding the cross sectional area of the cable, overtime and after erecting many different long wire aerials I've found no practical difference by spending a fortune on thick cable. There is no safety aspect when you consider it in all honesty. If you use the RF earth for your radios and them only then in reality there is no connection between mains and RF earth. Where it can fall down is AC DC sets, if following good practice then all your chassis's will be wired correctly to mains neutral, if the set has an aerial and earth connection then I'd also say the relevant caps should have been replaced as a matter of course with modern mains rated types. The only snag now though the RF earth will "see" noise from the mains neutral as the two are now coupled together at RF via the earth cap and chassis of the Radio. Where I stay I have dreadful noise from overhead cables, smps, powerline adaptors and other sources. To get reasonably noise free reception is a major challenge and I've even resorted to fully isolating the shed from the mains when I'm doing some serious listening. I use a transistor comms set at times fed from my 12 volt system. It's quite surprising the mains is such a good transmitter of noise, even a large inline RFI filter rated at 30amps doesn't make a big difference. The only thing that did help was a 10kW isolating transformer at the house end of the shed mains feed, with another earth rod driven into the ground and the effective new neutral grounded. It worked but was totally impractical and drew a couple of amps residual current, so as constant supply some what costly.
I'd like to hear how you get on and what works best in your location, sometimes the oddest things help noise and trial and error often is the best way.
Good luck.