Loading Up Power to A Vault

This is a question for your local electrician, who knows the codes for your area.

What would happen if everything started up at once? Would that exceed your cabinet capacity? What is starting/running? Motors? Heaters? Lighting?

There are Canadian members who may be willing to advise you.

80% continuous(3+ hours) load I think is max recommended.... so that would be 1600 amps@ 600v...

<...recommended...> By whom or by what applicable standard?

Who accepts liability if there is an incident as a result of this (rhetorical question - NNTR)?

If you have 3 x 666kVA single phase transformers forming a 3 phase bank, then

I_(A) = 1000 × S_(kVA) / (√3 × V_L-L(V) )

666000/ (1.732 x 600) = 640.87

641A continuous if looking at Line to Line current (@600V in your case).

Or did you mean you have 3 x 666kVA 3 phase transformers? You were not clear. If so, triple that value.

But to the earlier point, your local codes can be consulted for how to determine things like "diversity factor" and short term loading.

We have 3 x 666kVA 3 phase transformers so we have around 1922.61 amps available at 80% so at 80% that gives us 1538 amps (useable) we will get a "load study" done should we proceed with this project. I was asking the forum to get some idea what was the "industry standard" as if we do not have enough power its very expensive to upgrade the vault or if the local utility has any additional power available in our area

Thanks

You still have to support instantaneous inrush current for equipment starts, if all starts on a single command. Get a local engineering firm to provide your final answer.

No answer is accurate without a full and complete understanding of the nature of your distribution equipment. Mainly, you need to know what the nature of the overcurrent devices, and the gear they are installed in, are rated for in regards to maximum continuous loading and the nature of the conductors in the system.

You need to understand the nature of your current system and what additional loading, both continuous and non-continuous, is being proposed to make any sort of rational decision.

Call a reputable electrical engineering firm to assist you.

That would be determined by the settings of the circuit protective equipment devices, which cannot be seen from here.

<...We have...> As the panel is already in situ and in use there will be a set of drawings for the equipment and also a set of commissioning records. The answer to the question lies in those documents. If they are not to hand, the next best thing is to contact the original equipment manufacturer, and telephone is recommended in the first instance.