Physical Earth Ground?

[Rod D]

I've read a very interesting discussion on various grounding issues within our trailers from 2013. If I understand it all, the idea of equipment grounding to the chassis for instance allows for a very fast breaker kick or fuse blow and keeps US from being shocked or worse. I'm wondering what the effect of allowing the ends of the safety chains, or something like that, laying on the ground will have? While not as certain as a grounding rod driven into the earth, it still should give the energy from a short to ground an easy path. Is that good?

[steve dunham]

Originally Posted by Rod D

I've read a very interesting discussion on various grounding issues within our trailers from 2013. If I understand it all, the idea of equipment grounding to the chassis for instance allows for a very fast breaker kick or fuse blow and keeps US from being shocked or worse. I'm wondering what the effect of allowing the ends of the safety chains, or something like that, laying on the ground will have? While not as certain as a grounding rod driven into the earth, it still should give the energy from a short to ground an easy path. Is that good?

NO IT WON'T . Go to the AB Chance website and watch there video on ground rods . If you go to the NEC-Art 250 you will see that a ground rod is the least prefered method of grounding and is used as a secondary supplemental ground . Yes the chains may ground the frame but will perform poorly under fault conditions.
We used to check ground rods by connecting a wire to a hot source then through a 15 amp fuse and then hooking the other end of the wire to an 8 ft ground rod driven fully into the earth .. Many times we could not blow the 15 amp fuse ( NEC rule on ground rod .resistance) Try using a chain as a ground when welding. The chain will get so hot it will burn you due to the chains high resistance. Chain makes a lousy conductor. That is why there is a full size equipment grounding conductor in your trailer's service cord .

[Raz]

And even if you were to replace the chain with a wire, soil conductivity and lack of contact area would make for a poor connection. In a place like Florida, ground rods work very well due to soil moisture and make up. Here in Vermont we have rocky poor conducting soils producing poor grounding conditions. From time to time my local power company salts the pole ground rods to improve grounding.

[Rod D]

Thank you folks for your answers about possible grounding problems. I like to keep a neat campsite, but I do sometimes leave the chains on the ground (could just be an aging thing). Your answers make sense to me!

[Paul O.]

Originally Posted by Raz

And even if you were to replace the chain with a wire, soil conductivity and lack of contact area would make for a poor connection. In a place like Florida, ground rods work very well due to soil moisture and make up. Here in Vermont we have rocky poor conducting soils producing poor grounding conditions. From time to time my local power company salts the pole ground rods to improve grounding.

Salting the ground rods makes perfect sense, I never knew the power companies do that. The salty water conducts, "clean" water very little, distilled water not at all.
One small point for the benefit of the OP: 12 Volts will not shock you, you won't feel it, but a short will get hot and arc and potentially start a fire and burn you! When plugged into 120 Volt shore power, you can get shocked just like at home.

[steve dunham]

Originally Posted by Paul O.

Salting the ground rods makes perfect sense, I never knew the power companies do that. The salty water conducts, "clean" water very little, distilled water not at all.
One small point for the benefit of the OP: 12 Volts will not shock you, you won't feel it, but a short will get hot and arc and potentially start a fire and burn you! When plugged into 120 Volt shore power, you can get shocked just like at home.

The make a chemical mixture that is used with ground rods to lower the resistance . The mixture needs to be replaced over time but seldom is because people forget . Urine works to lower ground rod resistance better than watet so right before the inspector came we often watered the ground rod. Driving a ground rod at your trailer is not a substitute for the equipment grounding conductor in your service cord .And the notion that low voltage can not harm / kill you is false . Normally your skin resistance prevents you from low voltage shocks but in certain conditions you can lock up your heart with a 9V battery . In cardiac care / surgery areas of hospitals even static electricity is a huge issue. Lightning and ground rods is another area with its own set of issues. As Raz said there are too many variable when using the chains and even under ideal conditions would be a very poor ground.

[steve dunham]

Originally Posted by Raz

And even if you were to replace the chain with a wire, soil conductivity and lack of contact area would make for a poor connection. In a place like Florida, ground rods work very well due to soil moisture and make up. Here in Vermont we have rocky poor conducting soils producing poor grounding conditions. From time to time my local power company salts the pole ground rods to improve grounding.

I believe the "UFER" ( Named for its inventor) ground was developed in Arizona to overcome the issues with ground rods in a dry desert climate. New homes are required to use a UFER ground and a ground rod is no longer accepted. In Minnesota frost footings for homes are buried 48" to 72" below grade so the UFER ground works extremely well .

[Paul O.]

Here is a short article on Ufer Ground, interesting:
https://en.wikipedia.org/wiki/Ufer_ground
I don't think this well known in the Northeast of the US, we have pretty wet ground here.

[cmartin748]

One place that I boondock I camp near a fenced in area that has about 50 metal posts and wire mesh fencing. I think it makes a decent ground for my generator.