Now that LED has taken over the roadways with a choke hold  I was wondering . Since LEDs draw significantly less amperage that the previous HID fixtures did are utilities/municipalities changing the circuit protection ratings accordingly after the conversions ?? I'd assume with a complete new system install the needed changes are made by the lighting designer/engineer ?

 Honestly , the same question would have applied in the past when going from Incandescent or MV to HPS .

 Any thoughts ?

If only fixtures are being replaced, there is no need to change the protrction.
The reason is, the protrction only task is to protect the wiring. And as the wires remained, so their assumed robustness (assume tgere is no degradation affecting that, like a corrosion or so), and assume the design was correct the first time, the original protection rating should provide the same level of protection as it was designed for.

One may say when the fixtures draw less current, lowering the trip currents may provide an additional margin for safety, but as it was the case many times before, any efficiency improvement led to just more lights being installed for the same area, so rather increasing and not decreasing the loading and energy demand, so the installation will likely get loaded fully again...

 Thanks !! I also asked my brother today who is an electrical engineer and he said the same thing .

I’d guess no, as Medved says, the circuit protection was there to protect the cables, and as far as I know, our LED changeover was just columns and lanterns, the cables were never changed?

I have seen conversions where they combine 3 circuits into 1 at the panel because of the drop in amps. Reduces space needed by the panels. But the oversized wires are left in place unless they are bad.