Get some ABB industrial contactors, with appropriate coil for your supply voltage ( you will probably be limited though, they come in 12VDC/24VAC, 24VDC/48VAC, 110VDC/220VAC and 240VDC/400VA) and a 16A contact rating, which will typically be a 4 pole configuration of 3 16A double break contacts and a 10A auxillary contact. Lifetime is around 5 million cycles at part load, 1 million at full load. DIN mountable directly, and they are standard items. Expensive, use around 10W in operation and make a clunk on switching, but they do go on forever.
I have some that are on 30 million cycles or so, and they are still working well.