Regardless of standards ... how are you going to troubleshoot it?

Regardless of standards ... certain troubleshooting operations can only be done with the power on.

If you force the maintenance chap to bypass or overrule interlocks in order to find out if a PLC input is turning on, that maintenance chap is not going to be a happy camper and someone is going to get in trouble. If you then rigidly enforce lock-out procedures then you are going to end up with a very safe machine, because the moment anything goes wrong, it will be prohibited to troubleshoot it because you will not be able to do it without doing something illegal, and the machine will thus be very safe because it won't ever work again (legally).

Make the panel accessible from outside, like everyone else does.

I'm not the person making the call on this. I agree with what you're saying.

These standards are based on risk assessment. There has to be a risk assessment associated with the equipment. Make sure you have the following items covered:

f) troubleshooting;
g) correction of malfunction(s) (e.g. equipment jams, dropped parts, event recovery and abnormal
conditions);
h) control of hazardous energy (including fixtures, clamps, turntables, and other equipment);
i) maintenance and repair;

This is a cut-and-paste from ISO 10218-2 s. 4.4.2. I don't have 13849 handy, but every piece of machinery to which that standard applies requires a risk assessment because that standard is based upon risk assessment.

Thanks Brian, good point. Will do arisk assessment and see what we come up with.