tt ground to phono section. solid copper?

     I have to have a ground on my vpi classic it buzzes like mad without it.I had it straight to my pre ground phone inboard.I am switching to the external phono,It has a ground terminal and a 2 prong dc conversion plug.My question is would it benefit me to go from it it to my pre ground also because the plug is not grounded ? The reason I asked may be a novice question,I remember when grounding large things to earth like a hottub a solid core wire is used it made me curious.Yes I use a 16 gauge stranded spaded wire now.
With acoustic zen matrix reference 2 cables which made a huge! difference over the blue jeans( another thread entirely) night and day ...

ok jea48 
thanks for the insight ..

@jea48 is kind of mostly right.

It's not a safety ground, so practically any gauge will do, but ...when it connects at the phonograph preamplifier's chassis I believe, which in turn should connect to the earth through the preamp's AC plug, when present.

This is another reason why the safety ground on a preamp should never b e disabled.  A lethal voltage could develop at the tonearm or fire created when that wire melts due to an AC short in the preamp otherwise.

Of course, it's very very rare.

Best,

Erik