I do not think it will be that heavy. I was thinking around 90 to 100 kilos.

It will be heavy that's for sure but you can have it so that you can install the transformers one by one making it sort of modular install.

The transformer is where all the weight it.

I forgot to add the weight of the metal case. The plastic ABS will not hold that weight. Metal case alone weighs in at 27 kilos.

That would put the weight at at 120 to 130 kilos.

The metal case will be something like this

An intermediate solution might be a light weight case with metal supporting brackets for the transformers bolted through the back / bottom to the supporting structure.

Here is another box

It comes in at half the weight but I do not know if it can handle the weight of the three transformers. The metal one not a problem with some extra bolts.

AS wiseguy said, there is no need for code change, just one of his nice auto connect disconnect boards for the third stage.

Just a thought, as adding a second or a third power stage is so simple with this design, it could be make easier to move and service by fitting the [Toroid, chokes and Power board] for each power stage in separate small metal encloses, they could be latched together and the controller mounted in one of them if desired or separately in a very small control enclosure, that would makes it very easy to service and move.

That would work modular install.

However I am thinking for my install I will leave everything open to air this way no need for fans and just cover it up with 3mm plexi glass for safety.

Just large heat sinks would be enough on the power boards.

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AS wiseguy said, there is no need for code change, just one of his nice auto connect disconnect boards for the third stage.