Underground Splice/Tap


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Old 06-19-07, 09:24 AM
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Underground Splice/Tap

I need to create an underground splice/tap. Do the underground splice kits (heat shrinkable cover) allow for a new wire so that that i have one line going into the splice and two lines coming out?

Im wondering of teh plastic, when heated , will mold around two wires side by side, or on top of each other.

My alternative is to not create this splice - which I am doing to add a receptacle - so that I can avoid running an extension cord that will be in place for a few months out of teh year (used for garden accessories - lights and fountain)

Any thoughts on this?
 
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Old 06-19-07, 09:29 AM
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not sure wat an underground splice kit is but if it's anything like a normal wiring splice? and you're wanting to use a plastic connector...u can clamp one wire on one side and then clamp two in the other, then use a lighter (or w/e) and carfully shrink the plastic around it ...

but i dont kno if thats wat you're talking about or not

-trent
 
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Old 06-19-07, 10:26 AM
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You cannot make an underground splice. All splices must be in permanently accessible junction boxes.

Explain what goal you're trying to accomplish and we may be able to propose a better solution.
 
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Old 06-19-07, 10:47 AM
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The kits you are talking about are designed to repair a damaged underground wire.

You can't create a junction underground like you want, you must instead install an above ground junction box.

As Ben suggested, why not tell us your situation and perhaps we can help.
 
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Old 06-19-07, 11:33 AM
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are you sure it cant be done by code? These products make me think it can:

http://electrical.hardwarestore.com/14-46-heat-shrink-tubing/underground-cable-splice-kit-601571.aspx

http://www.amazon.com/GB-Electrical-HST-1300-Underground-Splice/dp/B00004WLKR

http://www.etcon.com/etcon/prosplic.html

http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/11540/cid/4021

But in any case, I have a wire that runs, underground, from point A to point B which is 50 feet away.

I want to have a receptacle halfway beteen these two points - 25 feet from point A.

To run from the source or the existing receptacle has too many obstacles. The simplest route seems to be to cut the wire at the halfway point and add a new wireso that I can run a new receptacle from that new wire.

As i mentioned earlier, my other option is a 25 foot extension cord coming from the receptacle. not sure if that is such a good idea since it would be used for about 5 months out of the year.
 
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Old 06-19-07, 11:42 AM
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Yes, I am sure you cannot make a splice that connects three different cables. Those kits are designed to fix a break in a cable. They are not designed to tap into an existing cable and run a new one from it.

And doing so, even if you made it waterproof would violate code.

Do not do it.

Do not run an extension cord either. Install an above ground junction box if you want, or run the cable from an existing junction box.
 
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Old 06-19-07, 12:39 PM
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But I can use those to extend a wire , rigth?

The point B i mentioned earlier, which has a receptacle also has a wire coming from it that I had originally planned to use for a light.

I never got around to it so, it would save time if I use this wire (12 gauge also) since I wont have to completely uproot my existing PVC with receptacle box. I can just redirect this unused wire and backtrack to where I want to new receptacle.

But, this new wire wont reach the full distance, so I would need to splice in order to extend it another 10 feet or so.

Can I do that?

Also, what is the danger of a bad splice underground... you wouldnt make teh entire area above it electricified if your splice was bad - would you?
 
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Old 06-19-07, 02:08 PM
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"But, this new wire wont reach the full distance, so I would need to splice in order to extend it another 10 feet or so.

Can I do that?"

Yes, but plan to make the splices above ground. That is, you will need a j-box at that 10-feet-short point, above ground.

Maybe someone more knowledgeable can comment on the possibility of putting your splice j-box inside a valve box with suitable drainage. I am not sure what the NEC has to say about this.

Use something like this for your splices. Check your state and local codes to ensure they are permitted in your area, get a permit and have your work inspected:

http://www.aifittings.com/j_2.htm

"Also, what is the danger of a bad splice underground... you wouldnt make teh entire area above it electricified if your splice was bad - would you?"

If the circuit is GFCI-protected before the fault, it would most likely trip.

However there is always a risk. GFCIs must be checked regularly and they do fail. Although many situations are unlikely to kill someone, look up "stray voltage".

The problem is that you can count on any underground splice becoming submerged or just damp on a regular basis. The water and minerals in the soil can corrode your wires as well as energize something close by.
 
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Old 06-19-07, 06:29 PM
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See 300.5(E) of the NEC. This is _explicit_ permission to make splices and taps in underground wiring without the use of a box. You _must_ use splicing devices that are listed for underground use. Yes, this is a bit of code that is at odds with the generally required practise of putting all splices in junction boxes; but thems the rules.

See, for example http://www.kinginnovation.com/pdfs/50100-04-DryConnKing6Blue.pdf which can connect 4 #12 solid conductors, for direct bury, underground.

Having said this, IMHO making this splice underground is a _bad_ idea. Code is not a design manual, and bare minimum code is rarely a good design. It is merely 'safe enough' to pass the code writer's sniff test. If (When) the splice fails, you will be stuck having to find it. If this is a GFCI circuit, then you will be more subject to tripping from minor 'leakage'. Additionally, since there is no extra 'play' in the buried conductor, you will need some space to make the splice anyway.

At I minimum, I suggest that you put this splice into a suitable underground access box, commonly called a 'Christy Box' (this is a trademark, but is often used as a generic name). These are the 'Valve Boxes' that Arg suggested, and yes, they are used in just this fashion. Such a box is quite 'open'; often without a bottom; in fact one technique is to dig deep and put gravel below the box to allow for better drainage. The splice will most certainly be exposed to water, and you will still need to use a splicing technique suitable for underground use and wet use.

IMHO you want a better solution than an underground splice. While they are permitted with suitable materials, they are much more subject to corrosion and damage. Water is the enemy, and underground means wet. With suitable (and expensive) materials, you can keep the splice dry, but why make things hard on yourself.

For example, if you install a pair of new receptacles a couple of feet apart, then you can make all of the splices aboveground in the receptacle boxes. Simple, gets the job done, and no underground splices to worry about.

-Jon
 
 

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