Ground spike under a tire.... (Unsafe grounding practices)

[Franko]

Proximity to the watertable is the idea.  The spike in very (extremely) dry ground really is not that effective.........or so I believe.

Water/wet/moist ground conducts electricity, while dry ground is a poor conductor.

I can tell you that in another province at the FOB we had operational equipment that was checked by the techs for every conceivable technical error to the point of watering the spike with gallons of water but still couldn't get any further out than 3km. At one point we were 300m away and still couldn't raise the CP. Could have been a myriad of other effects affecting the kit. Frustrating to say the least.

Everything was done with other means.

Regards

 

[chrisf]

So is that where the practice of watering the spike comes from?

Regards

Regular watering of the spike will improve conductivity to ground (Though you'd be amazed how many people don't know that's why the spike is hollow)

Radial grounds are another improvement on that.

There's other options as well, deeper grounds, grounding plates, grounding networks.

 

[Swingline1984]

There are also chemical grounds as well.  For radio systems there are also things called 'false' grounds, which by their very nature, mimic ground but don't provide much protection from external sources; lightning being an example.  I've heard tell from some of the older more seasoned HF operators that one practice was to use an empty beer can filled with water, the can coming from the requisite 6 pack in everyones ruck.

 

[Sig_Des]

I remember seeing something that I thought was pretty ingenious, that could very well be useful in the urban/parking lot set-up.

Basically it was a grounding strap designed to be plugged into any regular wall outlet, and using it's ground. No need to worry about jerry-rigging something up, just find yourself an outlet.

I'm sure others know more about the science to it, but it seems like it would be something feasible.

 

[REDinstaller]

Des,

Electrical Gnd is only as good as the maint of the grounding system for the electrical side. With RDS, the electrical ground acheived through the power cord is never relied on, hence all equipment is grounded to its shelf, the shelf is grounded to the rack, the rack is tied to the Main Terminal Ground used for the Bldg comms closets. This avoids ground potential, and ground loops that are common in electrical systems. It is possible that some electrical circuits ground voltage is plus or minus of zero which an ideal ground should be 0. This puts risk to personel and equipment as both are unable to tolerate a ground potential which can be as high as the higest voltage used with in that bldg. This is why the genny tlr has a ground rod, and so does the veh hooked up to it.

 

[chrisf]

Terrible idea on the outlet. It's one of those "knowing just enough to be dangerous". There's way too much impedence to ground.

There's a difference between grounding and bonding. Grounding is the direct connection to the earth, bonding is what connects everything else to the ground. The "ground" in an outlet is not actually a ground, it's "bond".

The absolute bare minimum of the grounding conductor (Meaning the actual connection to ground) for a standard CP rad truck would be 8AWG, that's from the Canadian Electrical Code (CEC), I'm guessing the actual standard as dictated by the military is probably higher.

The bonding wire you'd be plugging into, if it's a normal outlet, is 14AWG. Not nearly sufficient safe grounding.

 

[REDinstaller]

The ground is provided by the ground plug on an outlet. Bonding is the mechanical action where by enough tension is applied to 2 surfaces of an similar material (copper to copper) that allows the maximun surface contact to be achieved. This removes ground loops and false or intermittent readings when grounds are tested.

 

[chrisf]

Straight from the code...

Bonding - A low impedence path obtained by permanently joining all non-current-carrying metal parts to ensure electrical continuity, and having the capacity to conduct safetly any current impsed on it.

Ground - A connection to earth obtained by a grounding electrode.

I realise it sounds like I'm trying to play a game of symantics here, I'm really not.

I'm not arguing with you per-say, as we're both saying the same quite the same thing, that grounding is important, and critical for safety, but these are the electrical definitions of bonding and grounding, and cause confusion quite regularly, even with electrical professionals.

A "bond" does not constitute a "ground" because as you pointed out, a bond may fail, or may not actually be connected to ground. Any point up until the spike itself is arguably a bond. A bond does not become grounded until (And straight from the code here) it is "connected effectively with the general mass of the arth through a grounding path of sufficiently low impedence, and having an ampacity sufficient at all times, under the most severe conditions liable to arise in practice to prevent any current in the gorunding conductor to prevent harmful voltage to exist".

The 14AWG bonding wire in a standard 15A electrical outlet is NOT sufficient to to provide connection to ground a standard rad truck.

I don't remember the max current rating of the standard power connection for a CP vehicle, but I do know for sure it's not more then a hundred amps. That being said, the minimum ground would be 8 AWG

My point with all this is that just because it's bonded doesn't make it grounded. The 14AWG bonding wire in a 15A outlet isn't even sufficient to bond it.

Far too often, especially with sig ops in my experience, it's again an issue of a little knowledge being a dangerous thing.

Example being the "cheater"plug Beadwindow 7 was referring to. Somone (definitely a sig op) knew they need to ground things for safety and comms. They know that the electrical system of a building is grounded. What they didn't know is that plugging into an outlet was not sufficient for a safe ground.

 

[REDinstaller]

Straight from the code...

Bonding - A low impedance path obtained by permanently joining all  metal parts to ensure electrical continuity, and having the capacity to conduct safely any current imposed on it.

Ground - A connection to earth obtained by a grounding electrode.

I don't remember the max current rating of the standard power connection for a CP vehicle, but I do know for sure it's not more then a hundred amps. That being said, the minimum ground would be 8 AWG

My point with all this is that just because it's bonded doesn't make it grounded. The 14AWG bonding wire in a 15A outlet isn't even sufficient to bond it.

Far too often, especially with Sig ops in my experience, it's again an issue of a little knowledge being a dangerous thing.

Example being the "cheater"plug Beadwindow 7 was referring to. Someone (definitely a Sig op) knew they need to ground things for safety and comms. They know that the electrical system of a building is grounded. What they didn't know is that plugging into an outlet was not sufficient for a safe ground.

That is why TBITS is the Communications installation standard for the CF. The max current for LSVWs would be the lowest rating in the veh power system. The power cable is just a long fuse when you push too much current through it.

When TCI's for Comms Systems are performed, we examine the Communications Grounds very closely. That's why power cables aren't a reliable ground. We can't verify where they are jumpered or terminated. Grounding the power cable is only for power, the ground lug on the patch panel is for the comms system protection.

 

[Swingline1984]

With regards to inside plant we bond to ground mainly for EMI.  The Telecommunications Main Building Ground (TMBG) is tied back to one of the following:  building structure, closest electrical panel, main building ground, and in some older buildings the water main; which in all cases are tied together.  This is, as you stated, to avoid differences in potential between the systems, preventing one system, through isolation, from using another as a pathway to ground at a point where they accidentally become common (usually structure).  In outside plant we bond to ground for high voltage i.e. Lightning.  The outside plant is fused to ground at it's entry point to a building.  It is also at this point the cable is no longer shielded and therefore the pathway (tray or EMT) acts in this capacity.  In RDS installations they take it a step further and either use fibre optic or STP for horizontal cabling.  The smallest ground cable used in a Telecom installation is usually 6AWG unless your looking at a frame and then it is 12AWG.  Don't get me started on antenna systems which run the gammit from huge buried ground screens, which are part of the array, to large flat ribbons to provide maximum surface area to disperse lightning strikes.  If you want some fun stories talk to some of the older Linemen about molecular bonds.

 

[chrisf]

That is why TBITS is the Communications installation standard for the CF.

TBITS?

 

[Occam]

TBITS?

TBITS 6.9, to be precise.

http://www.tbs-sct.gc.ca/it-ti/itp-pti/its-nit-eng.asp

 

[chrisf]

Ah. (To reiterate the original point of the thread, I suspect "just stick your spike under a tire" is not included)

 

[Swingline1984]

TBITS is a "standard".  Standards are flexible except where they point to Code.  Code is law.

 

[REDinstaller]

TBITS is a "standard".  Standards are flexible except where they point to Code.  Code is law.

And the code is the Canadaian Electrical Code, pertaining to electrical service.

 

[Swingline1984]

And the code is the Canadaian Electrical Code, pertaining to electrical service.

Not nessesarily.  You must adhere to whichever is the more stringent.  In some cases that is Provincial Code i.e. Ontario Electrical Code etc.

 

[REDinstaller]

This is true as well. I know that in Quebec, all the rubber coating must removed of flex conduit prior to its installation in any bldg.

 

[Sig_Des]

Far too often, especially with sig ops in my experience, it's again an issue of a little knowledge being a dangerous thing.

Example being the "cheater"plug Beadwindow 7 was referring to. Somone (definitely a sig op) knew they need to ground things for safety and comms. They know that the electrical system of a building is grounded. What they didn't know is that plugging into an outlet was not sufficient for a safe ground.

Thanks to T18A and others for explaining the science besided it.

A Sig Op...The strap I saw was actually the brainchild of an LCIS, but thanks for the trade-wide assumption of incompetence. I know that as of late you have something of a self-loathing towards the trade, and yes, there are idiots, but please don't generalize.

You've known me what, 6-7 years now? Yeah, I'll cut corners, but not with the safety of my det.

 

[chrisf]

A Sig Op...The strap I saw was actually the brainchild of an LCIS, but thanks for the trade-wide assumption of incompetence. I know that as of late you have something of a self-loathing towards the trade, and yes, there are idiots, but please don't generalize.

It's wasn't meant as an accusation of trade wide incompetence, but I appologise, as I can understand why you took it that way.

That being said, me being fed up with the trade doesn't come into it. Sig Ops don't get any electrical training, beyond basic safety and operation of small generating equipment. This includes a bit of theory. Unfortunately, a little knowledge being a dangerous thing, and people start tinkering with things that should be left to professionals.

While in fairness, this isn't limited to sig ops, it extends to anyone with a little basic knowledge of electricity and more importantly, access to electricity (Farmers and your typical home owner are common examples). I recently observed a light switch installed in somones home, wired with two pieces of CAT5 cable. Sig ops however, regularly meet those two criteria of having a bit of knowledge (Simple electrical theroy) and access to power (generators).

Fair enough, it was made by an LCIS tech, that doesn't make it safe, it's still dangerous, and shouldn't be used. Too much impedence to ground. Whoever made it wasn't familiar with proper and safe grounding practices. Unfortunately, they handed it off to somone who assumed that since it was made by an LCIS tech it was ok.

 

[MOOXE]

How do you test your ground?