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MCB & Cable Size for 3 Phase Star (Wye) with Neutral

Hi, I'm trying to understand/figure out what MCB & Cable Size would be required for a 3 Phase 9kW Immersion Element wired in Star using Neutral? I have been a little confused by the results when using various online calculators. One example here: https://www.watlow.com/resources-and-support/engineering-tools/3phase-delta-wye-calculator

i.e. Using a Line Voltage of 400V equals a Phase & Line Current of 12.99A. Where as using a Phase Voltage of 230V equals a Phase & Line Current of 22.59A?

My questions are:

1. Are these calculations correct?

2. What Amperage MCB would be required?

3. Would the MCB required need to be 3P, 3P+N or 4P?

3. Would 1.5mm2 cable at a 6 meter run be adequate?

Thanks in advance for your feedback and help.

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0 Former Community Member over 4 years ago

Why would this be the case?

I'm not sure what to say, Dan, I simply don't get those results when I use the calculator - see attached screenshots.

What is TT earthed?

'TT' is an acronym for Terra-Terra where 'Terra' is latin for 'Earth' (or Terre-Terre in French). It means that supply and consumer are [only] connected by the general mass of the Earth i.e. the consumer has a grounding rod. Care needs to be taken to ensure the earth loop impedance is sufficient on TT earthing systems. This in contrast to TN-C systems (Terra-Neutral-Combined) where the consumer Earth is provided by the utility company so an earthing rod is [usually] not required. More info here.
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0 Former Community Member over 4 years ago

Why would this be the case?

I'm not sure what to say, Dan, I simply don't get those results when I use the calculator - see attached screenshots.

What is TT earthed?

'TT' is an acronym for Terra-Terra where 'Terra' is latin for 'Earth' (or Terre-Terre in French). It means that supply and consumer are [only] connected by the general mass of the Earth i.e. the consumer has a grounding rod. Care needs to be taken to ensure the earth loop impedance is sufficient on TT earthing systems. This in contrast to TN-C systems (Terra-Neutral-Combined) where the consumer Earth is provided by the utility company so an earthing rod is [usually] not required. More info here.
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MCB & Cable Size for 3 Phase Star (Wye) with Neutral

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