Frame Ground/Chassis Wire

[multi-task]

Thanks everyone, all of your replies have helped with what I needed...and given me more to think about

[Jared J]

If it says to do it, I would do it, but I don't get the reasoning given here.

Obviously, this only applies to my camper...I know nothing about his. The wire passes through a connector in the fiberglass of the camper, and to the converter that is mounted to wood.

All 12v items are wired to ground by wires, nothing attaches to the frame at all. It's physically impossible for 120v to get to the frame, and there is only 3' of frame that the dc could get to, after it went through the wire insulation, and wire loom.

It's also almost physically impossible to be getting a hot from the service cord, etc., and touch the frame at the same time, so again...not seeing where it would help.

[stevebaz]

My scamp did not come with a converter just 120 volt Ac with one breaker. the 12 volt system was seperate. The ground from the cord to the breaker box was also bonded to the frame. The 12 volt battery was grounded to the frame. the electric brakes and breakaway switch are grounded to the frame. The tow and its battery are grounded to the frame when hooked up. When I rewired and put in a converter I bonded to the frame. Better safe than sorry. In a perfect world no one gets hurt and stupid things dont happed but it only takes one guy to put a screw in the wrong place to screw everything up.

[multi-task]

Here is a link to the converter manual:

http://www.bestconverter.com/assets/...B%20Manual.pdf

Near the top of page two, under "120 VAC Connection", it states:

"Using an 8 AWG minimum size copper wire, attach from the vehicle/device chassis to the Converter/Charger Bonding Lug."

That's really the only reason why I considered connecting it, so I figured if I was going to do it I'd also make sure the wiring was weather protected.

[Darwin Maring]

steve dunham hit the nail on the head. Do what he said and you r golden.

[bomni]

Hi All,


Since you are all talking about grounds. I have a question about grounding the electrical outlet box for the shore power. I have little expertise around this stuff but I managed to rewire our 1972 Boler interior and exterior lighting as well as the PD converter without any issues. I had not dealt with the 110 side of things as we just finished the restoration last year and we were not going to private campgrounds that season.

This year I would like to finish everything so I obviously need to ground the outlet box but can I ground to the same spot as the converter on the frame? This spot is the only ground I have and we don't have any luxurious electric items in our egg.

Thanks,

Matt

[bomni]

TTT


Any Boler owners out there to help?

[felix2]

Keep in mind that with 120V, there is a difference between a grounded neutral, and an equipment grounding conductor (EGC). A neutral is the return path of the electrical circuit, which is earthed at the neutral bus (which also carries the circuit ground conductor); the purpose of an EGC is to ground the equipment/housing/junction box. You would not mix the neutral and EGC. The EGC merely provides an earthing means for the device's housing, in case it should somehow become energized.

Isn't electrical fun?

[Jon Vermilye]

Originally Posted by felix2

Keep in mind that with 120V, there is a difference between a grounded neutral, and an equipment grounding conductor (EGC). A neutral is the return path of the electrical circuit, which is earthed at the neutral bus (which also carries the circuit ground conductor); the purpose of an EGC is to ground the equipment/housing/junction box. You would not mix the neutral and EGC. The EGC merely provides an earthing means for the device's housing, in case it should somehow become energized.

Isn't electrical fun?

To add more "fun" the equipment ground does not have to be "earthed". For example, when powering a trailer from a Honda inverter generator, you still have an equipment ground (it is the metal frame of the generator) but no earth connection. In fact, you also have no bond of the neutral to the earth. While completely safe, that can present a problem for EMS systems or most surge guards such as the Progressive EMS-HW30C Surge Protector that I have on my trailer. They will assume there is an open ground because of the method the manufacturer used to detect the ground connection. A 3 lamp tester will also show a fault.

One of the ground conductor's primary purposes is to trip a fuse or breaker if there is a fault to any metal in the home (or RV). This is the reason for bonding the frame & other metal to the ground conductor.

[steve dunham]

The primary purpose of the equipment grounding conductor is to assure a low impedance path to ground and facilitate the tripping of the overcurrent device as quickly as possible The equipment grounding conductor is not designed to be a current carrying conductor except under certain select conditions (Fault) In certain instances the code requires metallic raceways as well as an equipment grounding conductor to assure a low impedance path "redundant" (Coronary Care Units) . Secondly bonding and grounding are not the same term . Swimming pool equipment is bonded but not necessarily grounded .Rebar ,railings ,ladders drains etc are bonded . The grounding of your trailer frame limits the voltage to ground for safety reasons.. The biggest problem I have seen is when people use grounded and grounding as meaning the same thing "THEY ARE NOT" They use equipment grounds as current carrying conductors or neutral conductors as equipment grounding conductor or my favorite "Just tie all the neutrals together they all go to the same spot in the breaker panel (See festoon lighting in the NEC)

[Byron Kinnaman]

Originally Posted by steve dunham

The primary purpose of the equipment grounding conductor is to assure a low impedance path to ground and facilitate the tripping of the overcurrent device as quickly as possible The equipment grounding conductor is not designed to be a current carrying conductor except under certain select conditions (Fault) In certain instances the code requires metallic raceways as well as an equipment grounding conductor to assure a low impedance path "redundant" (Coronary Care Units) . Secondly bonding and grounding are not the same term . Swimming pool equipment is bonded but not necessarily grounded .Rebar ,railings ,ladders drains etc are bonded . The grounding of your trailer frame limits the voltage to ground for safety reasons.. The biggest problem I have seen is when people use grounded and grounding as meaning the same thing "THEY ARE NOT" They use equipment grounds as current carrying conductors or neutral conductors as equipment grounding conductor or my favorite "Just tie all the neutrals together they all go to the same spot in the breaker panel (See festoon lighting in the NEC)

I don't believe the first paragraph is exactly correct. Safety grounding was required long before GFI devices were invented. The purpose of the safety ground is keep the ground (earth) at the same electrical potential as any metal on the electrical device. Thus eliminating shock hazards.
GFI (Ground Fault Interrupt) measures the current differential between the hot and neutral lines, If they aren't the same the hot connection is removed. Safety ground and GFI are entirely separate.

Use of safety ground (including trailer frames) for current carrying conductors is not a good idea.

I'm not sure what your statement about tying all the neutrals together means. I'm guessing that somebody is including safety ground with neutral. In that case, tying safety ground to neutral in any location other than at the distribution panel is asking for trouble in the form of shock hazards.

[Jon Vermilye]

Tripping an over current protective device has nothing to do with GFCIs. Steve is correct - if a hot side connection or insulation faults to any metal that is accessible, it is critical that there is a low impedance path that will force the tripping of the breaker or fuse, weather or not there is a GFCI protecting the circuit. The Equipment Ground Conductor (the bare or green non current carrying wire) is there for that purpose.

Prior to the 1960's wiring was 2 wire - a hot & neutral. During the early 60's a undersized ground wire was added & used to protect the metal boxes, but not carried through to the receptacle. The purpose was to protect users from a shock from the metal receptacle covers by tripping the circuit's fuse or breaker if there was a fault to the metal box.

I believe it was the 1965 code that required a full sized ground (for 15 & 20 amp circuits). Grounding (3 pole) receptacles were required with the 1975 code, although they were available before that time and often installed. My code history notes are on loan, so I may be off a code or two.

[steve dunham]

Originally Posted by Jon Vermilye

Tripping an over current protective device has nothing to do with GFCIs. Steve is correct - if a hot side connection or insulation faults to any metal that is accessible, it is critical that there is a low impedance path that will force the tripping of the breaker or fuse, weather or not there is a GFCI protecting the circuit. The Equipment Ground Conductor (the bare or green non current carrying wire) is there for that purpose.

Prior to the 1960's wiring was 2 wire - a hot & neutral. During the early 60's a undersized ground wire was added & used to protect the metal boxes, but not carried through to the receptacle. The purpose was to protect users from a shock from the metal receptacle covers by tripping the circuit's fuse or breaker if there was a fault to the metal box.

I believe it was the 1965 code that required a full sized ground (for 15 & 20 amp circuits). Grounding (3 pole) receptacles were required with the 1975 code, although they were available before that time and often installed. My code history notes are on loan, so I may be off a code or two.

Jon I think you are correct when I started day school we were using the 1965 NEC and romex was required to have a full size equipment ground . Previously 14-2 romex had a # 16 equipment grounding conductor which often suffered mechanical damage and the loss of ground . Secondly as you stated a GFCI is not an overcurrent device nor is it designed to be used as one (. Take a short piece of wire and short out a GFCI receptacle ,(Hot to Neutral) the fuse or breaker trips not the GFCI) .Lastly often time people without a understanding of electricity will find a junction box with two or more circuits and do not keep the neutrals separate ( There all white so just splice them all together method) causing parallel neutral conductors or you can shut off a breaker to the circuit you are working on and discover there is neutral current from another circuit. An open neutral is just as deadly as a Hot conductor. The old neutral (grounded conductor) rule is pick it up first ,lay it down last I know grounded outlets were required in 1971 and the GFCI requirements started around 1973

[Byron Kinnaman]

Originally Posted by Jon Vermilye

Tripping an over current protective device has nothing to do with GFCIs. Steve is correct - if a hot side connection or insulation faults to any metal that is accessible, it is critical that there is a low impedance path that will force the tripping of the breaker or fuse, weather or not there is a GFCI protecting the circuit. The Equipment Ground Conductor (the bare or green non current carrying wire) is there for that purpose.

Prior to the 1960's wiring was 2 wire - a hot & neutral. During the early 60's a undersized ground wire was added & used to protect the metal boxes, but not carried through to the receptacle. The purpose was to protect users from a shock from the metal receptacle covers by tripping the circuit's fuse or breaker if there was a fault to the metal box.

I believe it was the 1965 code that required a full sized ground (for 15 & 20 amp circuits). Grounding (3 pole) receptacles were required with the 1975 code, although they were available before that time and often installed. My code history notes are on loan, so I may be off a code or two.

Tripping a circuit breaker or blowing a fuse has nothing to do with 3 wire ground. The third wire is there to keep the metal, whether it outlet box or the side of your toaster, at the same potential as the earth. You CANNOT increase the speed at which an over current device trips without changing the over current device.

[Jon Vermilye]

Yes it does. If there was no ground wire, a fault to a metal receptacle box would make the box live to a near by ground or the neutral. A metal cover attached to the strap of the receptacle would make the cover at the same potential as the box. Again, this would be a shock hazard. The purpose of the ground wire is to cause a large amount of fault current that will trip the fuse or breaker.

There are examples where the ground is not at the earth potential - I mentioned a Honda inverter generator as an example in a previous post, In fact, there are examples here that point out some advantages on not grounding.

I suggest spending some time reading Article 250 in the NEC and at the Grounding vs Bonding section of the Mike Holt forum.

[Raz]

I'm with Jon on this one, hot to case opens the breaker. Also, you don't want anything you can touch carrying current. (I think Steve mentioned that). If it is, then there can be a voltage present. Raz