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Grounding Cable Improvised from Extension Cord

Brasidas

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After a frustrating experience being sited on top of a concrete slab for more than a few times, I would like to improve my det's flexibility in where it can place a ground.

My reserve squadron has a tech shop, along with two class A LCIS techs (yes, some still exist). They've requested materials for making new grounds for months, with no hardware showing up yet.

I've received some support from higher to come in and improvise a 30ft grounding cable for use in situations where the det has been sited at a distance from ground I can hammer the spike into. I have long extension cords and standard generator spikes available, and possibly some connectors from the tech shop. I must have the resulting grounding configuration approved by an LCIS tech when he comes in.

I will be speaking with an LCIS tech at next opportunity, though it could be september before I can wrangle one into a face to face meeting - between their jobs and the training year winding down. I expect to be able to come in and play well before I can discuss this with a tech at my unit.

There's a ground wire in a standard 3-prong extension cable. What do I need to do to get a grounding cable and spike approved for use with a sigs det?  Does it *have* to be official inventory grounding cable?  I've used cables with wire wrapped between washers without proper connectors before - is this considered acceptable?
 

PiperDown

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Probably not a good idea ( and against code ) to use an extension cord for a purpose other than its design.

Also....You have to remember  that a standard 3 prong electrical extension cord is 12-3-G, meaning 12 gauge ground and 3 wire.  12 gauge ground is only rated for 20 amp circuits.  As you go down in wire gauge, the rated amperage goes up.. Ie. 10 gauge is rated for 30 amps.
You need to pay careful attention to the amperage of your system you want to ground, and the gauge of the ground wire.  There are tons of references online that can fill in the blanks once you have some information about the system you want to ground.

Just to make it a little more confusing..  A smaller gauge does not always mean better ground.  As well all know, current flow is greatest down the path of least resistance. ( a tree trunk thick ground wire wont be the path of least resistance ! )

Improper grounding with either fry your system (because the ground provides no protection) in a power surge, or the ground wire itself will get very hot and start a fire.


Best bet...  I will leave the extension cord for your coffee maker and figure out what gauge wire works best, then go to a hardware store and buy some if you cant get it through the system.

Hope that helps.

 

chrisf

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Solution - longer grounding cable.

Don't just slap any ol' wire in there as an extension though, I believe I covered the minimum gauge for grounding an LSVW communications shelter in the other thread. If not, I'll look it up.
 

MOOXE

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For Op Cadence our CP (4 x LSVW) was cited on the Pearson Airport tarmac. I can't remember what guage grounding wire we used but it was almost as thick as your standard extension cord. They were very long as well, around 75ft for the longest one. They hooked up to this portable (on wheels) power distribution cabinet outside which was in turn grounded to something else quite a distance away. They were made by Black & Macdonald contractors. Everything worked great, not a single problem.

You could get this stuff at Home Hardware or Home Depot no problem.
 

REDinstaller

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Your ground wire may have been the same diameter as an extension cord, BUT your extension cord has 3 conductors inside the same jacket. This means that the extension cord only contains 1/3 of the ground potential as the 16 ga ground wire.
 

chrisf

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8ga (copper) is sufficient (according to the the electrical code) for grounding an LSVW. Bigger is better when it comes to grounding though.

For a longer distances distance, and for improved transmission, I'd recommend 6ga. Insulated or not, doesn't matter.
 

REDinstaller

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Insulation adds to the safety factor, along with adding to the longevity of the cable by keeping the elements out of the braid, and degrading the capability of the ground potential.
 

chrisf

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True enough.

But insulation still not required, if the option is between having an uninsulated 6ga grounding cable and not having a 6ga grounding cable at all, take the uninsulated.

I only add that it doesn't have to be insulated as I've had people very concerned in the past about "bare wires" being "unsafe", in reference to grounding wires.
 

REDinstaller

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But when it comes to the money issue of insulation or not, never pick the not. If you can keep your grounds out of water by being internal installations then uninsulated will last a long time. But for external building installations, insulated is the best for long term. Unless you have no other choice.

Money is always the worst design criteria, as it will comprimise safety every time.
 

chrisf

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Larger gauges, insulated/non-insulated shouldn't make much of a difference in cost. If your purchasing new, shouldn't make any much of a difference. Biggest cost of cabling right now is the copper. If you're purchasing a cable for grounding portable equipment, stuff with finer sub-gauges is probably better, more flexible, generally stays in grounding lugs better.

Aluminium is actually becoming popular again in new construction.

You're helluva right about the money issue... "meets code" means just that, meets the code... nothing worse then installing cheap parts that "meet code" that are just going to break in a few years regardless...
 

REDinstaller

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Funny you mention aluminum, I wouldn't put it in my house. Much too britle when used in tight corners, and you can't add copper into an aluminum system and vice versus. More of a headache then help. Copper is still the better conductor, and it doesn't oxidize in seconds unlike aluminum.
 

chrisf

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Never said it was "good", but it's a good example of "meets code" :)

Aluminium alloy/Aluminium Conductor Steel Reinforced are pretty much the standard for transmission lines, have been for a longtime, but it's becoming common in new construction buildings again.

If it's installed right, it's safe, but it comes down to how much you trust your installer, and how thorough your your inspecter is. Lot less margin for error than with copper wiring. Industry has learned a lot since the "early" days of aluminium wiring, but I'd still be wary of any aluminium installed in the near future... I give it 10 years till it's a common industry standard, but till then, most installers aren't familiar with it.
 

Occam

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a Sig Op said:
Aluminium is actually becoming popular again in new construction.

Where did you hear this?

Aluminum wire in residential gauges is difficult if not virtually impossible to source, and the cost of CO/ALR -rated switches and outlets would make wiring a house with AL ridiculously expensive.  You can get 5 CU single pole switches for the price of one CO/ALR switch.

If you're talking about commercial installations for distribution, that's another matter.
 

George Wallace

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Occam said:
Where did you hear this?

Aluminum wire in residential gauges is difficult if not virtually impossible to source, and the cost of CO/ALR -rated switches and outlets would make wiring a house with AL ridiculously expensive.  You can get 5 CU single pole switches for the price of one CO/ALR switch.

If you're talking about commercial installations for distribution, that's another matter.

Not only that, but it was the next thing to banned as being a Fire Hazard in the past.  What has changed?
 

Occam

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George Wallace said:
Not only that, but it was the next thing to banned as being a Fire Hazard in the past.  What has changed?

It was never near being banned.  The CEC still allows it, actually.  It's just got a lot of rules for its use...or at least more than copper.
 

chrisf

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Installation methods aluminium and the price of copper changed. Big issues with early installations were connections coming loose due to conductor expansion during heating. There were a few other issues as well.

You won't find it in residential construction (yet, for better or worse, it's coming eventually), not economical yet. As occam pointed out, devices rated for connection to aluminium are more expensive. There are also a few other points involved in installing aluminium that aren't required for copper.

You'll see it in new construction service entrances, feeders, and branch feeders in commercial/industrial applications now. Not "common", but getting more common every year. A lot of people are wary of it, and specify no aluminium because of the reputation aluminium wiring earned in the 60s/70s, but IF it's installed properly, it's safe. Comes down to your installer.

It's not really important to the original discussion about grounding connections though. For a portable ground, especially one being installed by amateurs, copper all the way.
 

George Wallace

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Actually, it was quite common in residential construction in the 1960's and 1970's.  It gained a bad rap due to poor installations and the fire hazards they produced.  Wikipedia has a couple of interesting pages to cover the topic:

http://en.wikipedia.org/wiki/Aluminum_wire

http://en.wikipedia.org/wiki/Electrical_wiring

The next question would be what would your Insurance Company demand in higher fees or building upgrades?

This is probably more on peoples' minds:

http://www.esasafe.com/pdf/Flash_Notices/09-08-FL.pdf

http://www.mississauga4sale.com/Home-Inspection/insurance-issues.htm
Aluminum Electrical Distribution Wiring

Single strand aluminum distribution wiring was installed in many homes between approximately 1968 and 1978. Due to its tendency to oxidize and its incompatibility with certain fittings designed for use with copper wiring, aluminum wiring has been determined to overheat in certain situations. As long as proper connections are used, and the connections are made without damaging the wire, aluminum wiring is considered safe.

For years, the presence of aluminum wiring in a home has been an item that, if installed and managed properly, has not been a safety concern. However, more recently, several insurance companies have been requiring (for new insurance policies) that the aluminum wiring be inspected by designated electrical inspection/safety authorities, and if necessary, requiring certain upgrades or repairs to fixtures in the home or in some cases, requiring replacement of the aluminum wiring with copper wiring.

 

chrisf

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You won't find it in new residential construction. It's still allowed by the CEC, however, some municipalities have banned it, and some organizations specify "copper only". You will see it in new residential construction again in the near (10 years) future though. I'd hazard a guess that even municipalities that have it banned will start to make allowances along the lines of "new construction only" and "for the use of professional electrical contractors only"

Price of copper is slowly going through the roof. If you have any plumbing work done in your house, don't let the plumber be "helpful" and take your old scrap pipe if there's anything more than a couple of pounds. It's worth your time to take it to a scrap dealer. I scrapped a few rather heavy brass lighting fixtures a while ago... scrap value paid for somone's retirement gift.

Anyone buying an older home with aluminium wiring would be wise to subject it to a thorough inspection by a competent electrician familiar with aluminium (All electricians *should* be familiar with aluminium, but make sure they *are* familiar with aluminium. I can tell you what needs to be done with aluminium, and I can read it out of a book how to install it, but personally, I've never touched it)
 
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