With the IEC plug feed the standard is that the live brown (black or red in the US) lead goes on the prong marked 'L' (right most on the last picture), the neutral blue (white or grey in the US) on the opposite prong, ground (yellow or green or y/g stripes) goes in the middle. Your wall outlet is hooked that way too - live is on the right. Inside the TT the polarity doesn't matter. Connect the neutral from the IEC plug to the blue wire if you want to keep the standard. If you're gonna add a fuse to this grounded scheme, make sure it's installed on the neutral lead. I always add 250V/0.5A fast acting fuse to all my TT's that I modify this way.