1) See SAE J1673 High Voltage Automotive Wiring Assembly Design
2) IP-2x Finger Proof Connector Design
3) High voltage systems are fully isolated from the chassis and do not use the chassis as a conductor - shock hazard is only possible with a multiple fault condition
Using a timing light to adjust the engine timing with a spinning fan blade a few inched from your fingers is certainly a safety issue. So is debugging cooling system problems on a hot engine. Loads of safety issues in the old days and loads now and in the future.
The bigger issue for independent mechanics is the expense of specialized tools and diagnostic equipment and the need to have different equipment for different cars. The tools and training are so specialized that it's quite likely to not be economically feasible to run an independent shop.
Very few auto mechanics work on engine innards these days, the replace the engine with a new or rebuilt one. I'm sure there will be a similar modularity and service will only be to the module level. The interconnects and interlocks will have to be robust and fool proof.
I can see this creating a market for specialised power packs.
You could get high performance power packs for racing enthusiests.
High endurance power packs for long distance drivers (not great at acceleration perhaps, but extended range).
Super economy power packs for people willing to trade performance and or range for lower cost.
This could create an entire industry. If there is anything people are willing to pay good money for it is tricking out their car.
Perhaps a better solution is to design the motor and battery into interchangable power packs. One block is a complete motor and control assembly and the other is a battery pack charger assembly. The mechanic swaps out the power packs and a highly trained specialist repairs the power pack back at a central depot.
This is how military armored vehicles are designed to permit them to be quickly gotten back into service by only semiskilled repair people. There are safety advantages to doing it this was as well. Part of the depot repair process could be to plug the power pack into a test fixture that fully tests it to ensure it meets spec. It could end up being cheaper to repair cars that way as well since the power pack would give the deport repair tech easy access to all components, automated diagnostics and dedicated jigs to simplify component replacement. The depot repair tech would also be highly proficient since this is what they specialize in.
This idea would make for a hell of a core charge for an independent mechanic though. Parts stores could include access to a test fixture to let independent mechanics verify their repaired power packs are properly repaired and safe to use.
A mechanic is working on the car because something is wrong or worse it has been in an accident. It is not unreasonable to assume that the safety interlocks could be damaged or have been bypassed by a shade tree mechanic.
Lethal voltage levels (~250VDC) are present in both the battery and the charging system. Both the batter and charging system are capable of delivering arc welding current levels.
If wiring is damaged battery voltage could be present on portions of the car (which could electrocute anyone who touches that part of the car).
If the battery pack is shorted out it could explode and release toxic chemicals. Fuses only work if they have not been jumpered around or been replaced with higher rated fuses to fix an intermitant problem with blowing fuses (caused by an intermittant short).
Nothing to worry about here as long as you have your trusty volt meter in your hand, right?
How many automotive mechanics are also licensed electrians? They will need to become the equivalent if they are going to work on high power electrical systems that the general public is exposed to.
I wonder if it will come to the point that before repairing a car the mechanic will need to pull a permit and get the car inspected before the car can be returned to the owner? This is pretty much how an electrician does business.
I wonder how much "safety buzz" was created when automatic transmissions were first introduced. They can be lethal too.
When tuning up a car, one of the steps is to adjust the idling RPM. In that step, one often gives the throttle a slight blip, just to be sure everything goes back where it belongs.
Easy enough with a stick shift. Car in neutral, parking brake engaged, no problem.
With an automatic, you set the idle with the transmission in park, and in gear. Wow! That can be dangerous. How many mechanics forget that the automatic transmission is in gear, when they blip the throttle?
So you have to be extra careful to make sure the car will not roll when you give it gas. Otherwise, the mechanic, and/or other mechanics, can be seriously injured.
All I'm saying is, why are we making such a big deal about hybrid maintenance safety, as if we haven't had this same problem from the beginning of time?
The manufacturers would have all kinds of interlocks and safeguards, but the technician has to trust that the manufacturer thought of everything. I would be a little uneasy about know knowing for sure that a wire isn't hot.