The only problem with a multi nation site is the materials change across boarders. I don't think Teck is an approved cable in the USA and ACWU is just wet location AC90 with aluminim conductors. a Jacketed armoured cable suitable for wet locations.
I would try and get all the panel feedeers run to the old panels and energise the new service first then chage them over 1, 2 or all over the week end.I would want the old service turned off asap.
