Heating Elements Arrangement.

There are several series/parallel combinations in which these elements could be connected. What is the rated voltage of each element? What is the available supply voltage?

mains supply = 415VAC, 3Ph, 50Hz

Elements voltage = 240VAC

Have you tried the manufacture? They would have a wiring diagram.

Here we need a crystal ball because we don't know enough about the discussed devices. Like others said, how are the elements arranged? Which is the nominal voltage per element? Is there one single or several thyristor units? Phase-angle or 0-volt controlled burst-fired? Or simply a basic static relay?

Remember that unlike mechanical contacts, semiconductors alone don't allow a galvanic separation.

"I have...." Look at it and see how it is connected. -- JHF

Connect them in delta, in banks of 3 branches of two series heaters each; that way if you have a burnt element the voltage won't increase accross the others, making them fail in a very short time, see:

Please dont connect them in star, it will cost you a lot of money in down time and heater replacements.

That will reduce their power output to less than rated. (207.5/240)².

Exactly, which will make them slightly "under-used" for the application, with the plus that you avoid voltage unbalance accross the series banks due to a unit going bad.

You hardly ever demand 100% of anything's capacity anyway.

I'm appalled, you read my post, thanks !

In any scenario, an open element will increase the resistance of its sub-network, and thereby unbalance the voltage upward. I haven't calculated whether this would be worse in the parallel-star arrangement versus the series-parallel delta scheme.

And then, one wonders what the geometric arrangement is, and the various jumper links that would be needed.

Thanks friends..