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Because I'm not totally confident he knows himself. He installed it as per the Manual but as I said it did not state 23 Amp in the Manual. He is someone I know through someone else and he is a qualified plumber who obviously does electrical work linked with plumbing, ie. heating, etc. He's due back tomorrow night for another reason but I was just eager for any other qualified information in the meantime. But thank you for your comment, I may need to contact a fully qualified electrician instead if all else fails.