How to

Powering down a high voltage system

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Powering down a vehicle’s high voltage system is an important task. You might be working directly on it to diagnose a problem with the vehicle, or making certain of your safety while working around it. 

With this video, pick up some tips on electrical safety during a high voltage disconnection from the experts at Delphi, and brush up your knowledge on: 

  • What rating is needed on the safety equipment 
  • How to find the power-down procedure for a specific vehicle 
  • The tests you should perform to ensure the vehicle is powered down.
Batteries Power Electronics How to Technicians 1 min read

What are the safety requirements on a high voltage system? 

Use only suitable tools and testing equipment (1000v CAT4 or Class 0). Isolate and lock off the electricity source as directed in the video. Test and prove that the electrical system is dead before commencing work. 

What is a safe voltage to work with on the powered-down vehicle? 

To ensure the vehicle you’re working with is safe enough to work on, your diagnostic tool should be picking up a voltage below 10 volts. 

What is the live/dead/live test? 

The live/dead/live test is used to confirm something is powered down by testing a confirmed live source beforehand, and once again after to check the equipment isn’t broken or providing a false reading of dead on the high voltage source.


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