Bare 3 phase bus bars....what isolated voltage is safe?

[opampsmoker]

Hi,
We will have isolated, bare,  three phase bus bars. Fully Mains transformer isolated. (mains input is 240VAC phase to neutral)
We're going to step down the 3 phase mains to the bus bars.
What is the highest VAC level that these bare bus bars can be at and not be a danger to humans touching them?
(ie touching one bus bar, and also touching between two bus bars with each hand)

[Siwastaja]

Approx 50VAC between phases. Exact value depends on jurisdiction, i.e., a function of location and time.

[mag_therm]

You would also have to consider the arc flash, related to the fault level.
That can happen when an operator drops a tool for example.
Or puts his meter probes across the bus and the meter explodes ( I saw that more than once, fortunately without injury!)

Is the "British Standard Finger"  still used?
I used them on  cabinetry/bus covers of the big rectifiers.

[Jeroen3]

Galvanic isolation is only a safety feature when you use it in conjunction with insulation monitoring.

Bare busbars are common in switchboards or distribution rooms.
There are some products available (eg: rittal) that insulate then minimally, to reduce the risks.

But the answer to your question is ELV: https://en.wikipedia.org/wiki/Extra-low_voltage