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Our service truck has a generator onboard to supply power for power tools, lighting etc. The truck also has a cord that can be plugged into a local outlet to power up the truck's accessories from another utility source. While being trained on the generator's operation, we were instructed to always bond the truck to ground (it has a cable with a ground rod we can jab into the ground) before starting the generator to prevent electric shock.
This seems backwards to me. It makes sense to ground the truck if taking-on external power because the oncoming power probably has a neutral that's tied to ground. But wouldn't grounding the truck for only generator use be creating a shock hazard?
For example, if I'm standing by the truck, barefooted in water, and I stick my hair pin the the hot hole of the truck's receptacle (truck ungrounded) am I completing a circuit? I think not. Now ground the truck and try the same thing and I'll get shocked, right?
It seems that an ungrounded truck is safer for generator use, while grounding the truck would be safer if taking on power from a grounded system.
During this training I had to speak up and ask, but I got dumb looks and comments about everybody knowing that grounding makes things safer. So... I did what I usually do in these situations, I made up a lie to back up my reasoning.
The lie goes something like this (I probably heard bits and pieces for real from somewhere).
Back in the day, when power was first being distributed, the power system was ungrounded. This was safer for people and pets, because simply touching a hot wire would not shock you. In order to be shocked you had to come between the hot and neutral wires and complete a circuit between them. Actually they weren't called hot and neutral because they were essentially the same. But there was a problem with the ungrounded system. Lighting would strike the power lines and huge balls of molten burning copper would erupt, burning houses to the ground for miles.
In order to fix the lighting problem, the system was grounded. But... This created a new problem. Now if you touch a hot wire while grounded, you complete the circuit and receive a shock. To help with this problem, we started grounding everything that could possibly become "Hot". That way, when the ringer washer motor shorted to it's casing, an over current condition would be created and the fuse would blow. Of course, before our systems were grounded the short wouldn't have been dangerous.
So... Our truck doesn't need lightning protecting when running the generator. Why create hazards by grounding the truck???
I thought my lie sounded pretty good so now I'm wondering how close it is to the real story?
This seems backwards to me. It makes sense to ground the truck if taking-on external power because the oncoming power probably has a neutral that's tied to ground. But wouldn't grounding the truck for only generator use be creating a shock hazard?
For example, if I'm standing by the truck, barefooted in water, and I stick my hair pin the the hot hole of the truck's receptacle (truck ungrounded) am I completing a circuit? I think not. Now ground the truck and try the same thing and I'll get shocked, right?
It seems that an ungrounded truck is safer for generator use, while grounding the truck would be safer if taking on power from a grounded system.
During this training I had to speak up and ask, but I got dumb looks and comments about everybody knowing that grounding makes things safer. So... I did what I usually do in these situations, I made up a lie to back up my reasoning.
The lie goes something like this (I probably heard bits and pieces for real from somewhere).
Back in the day, when power was first being distributed, the power system was ungrounded. This was safer for people and pets, because simply touching a hot wire would not shock you. In order to be shocked you had to come between the hot and neutral wires and complete a circuit between them. Actually they weren't called hot and neutral because they were essentially the same. But there was a problem with the ungrounded system. Lighting would strike the power lines and huge balls of molten burning copper would erupt, burning houses to the ground for miles.
In order to fix the lighting problem, the system was grounded. But... This created a new problem. Now if you touch a hot wire while grounded, you complete the circuit and receive a shock. To help with this problem, we started grounding everything that could possibly become "Hot". That way, when the ringer washer motor shorted to it's casing, an over current condition would be created and the fuse would blow. Of course, before our systems were grounded the short wouldn't have been dangerous.
So... Our truck doesn't need lightning protecting when running the generator. Why create hazards by grounding the truck???
I thought my lie sounded pretty good so now I'm wondering how close it is to the real story?