Splicing 1/0 aluminum power wire

[Jason280]

I'm running a 100a sub panel in an extra shop I've built, requiring approximately 125-150' of power wire. I've already bought 1/0 3-wire aluminum cable, and dug a trench to the shop. Problem is, I literally ended up 12-15' short of the panel. I'm pretty much stuck using the wire I have, so I picked up an underground splice kit from a friend who works with the power company.

What potential issues or problems will I run into splicing the power wire running to the shop? It will all be buried, and the splice kit uses **** style compression connectors and two impressive pieces of heat shrink per connector. I would love to have gotten a piece of wire long enough, but that simply isn't an option at this point (and 90% of the cable has already been buried and packed).

Thanks!

 

[godzilla]

I would run the wire above ground to terminate it ( splice it), to a mobile home non fused disconnect. Then add the extra length of wire you need for your run under ground. So you would have two pieces of conduit running up to the disconnect above ground.

 

[Jason280]

Is the biggest (potential) problem simply with water intrusion into the connectors?

 

[JoeFin]

Is the biggest (potential) problem simply with water intrusion into the connectors?

Yes

The aluminum will turn into dust (oxidation) in about 1 month

 

[pmiranda]

I would keep it accessible. Actually I'd try to find somebody that wants to buy it and then get the right length of cable. Doing it right the first time is always better in the long run (no pun intended).

 

[rockwithjason]

Splice it in a hand hole so you can access the splices as needed. Leave plenty of slack in the handhold for repairs. This will give you the best fighting chance by keeping the Splice out of the dirt.

 

[53Sparky]

What potential issues or problems will I run into splicing the power wire running to the shop? It will all be buried, and the splice kit uses **** style compression connectors and two impressive pieces of heat shrink per connector.

Trust the underground splice from the utility company. They do this thing a lot. It works. Just make sure the conductors are as clean as you can be when you do the heat shrink so there isn't a path for moisture to wick through.

If you're nervous, make a map of the location where the splice is and put it in the sub panel when you're done. The guy who buys your place in 20 years will appreciate it, even though he'll probably never need it.

 

[tab2]

Splice it in a hand hole so you can access the splices as needed. Leave plenty of slack in the handhold for repairs. This will give you the best fighting chance by keeping the Splice out of the dirt.

This is what I would do.

 

[mburrus]

make sure the connectors have an inhibitor paste and that you wire brush using a STAINLESS brush through the inhibitor paste. if its heat shrink with adhesive, youll be fine. are the connectors crimp or bolted? proper torque and proper crimp die are important!!!

made thousands of these splices in direct burial utility install...

why the hell did you direct bury this stuff? i would have (and actually am) run pipe... easy to replace if needed!!

 

[sberry]

Depending on conditions,,, but toss a piece of plastic over it a couple inches above and cover it. These are done all the time. It aint great but it is what it is. Connections are done downhole in wells all the time.
I pulled one up we had buried a long time ago, had slipped a piece of black rolled poly pipe over it and shot it full of silicone from both ends. We cut it apart with a razor knife just for giggles, looked new inside.

 

[pattenp]

Another problem is you said 3 wire cable. NEC requires 4 wires for sub feeds.

 

[walrus]

Splices are done underground, direct bury all the time. They have UL listed splice kits that if done per instructions will out last many of us. I agree with previous poster who pointed out 3 conductors is one short for a sub panel though.

 

[matt_i]

Another problem is you said 3 wire cable. NEC requires 4 wires for sub feeds.

Exactly. The neutral and ground need to be separated going back from the sub panel. 3 wires = wrong wire.

 

[theoldwizard1]

Is the biggest (potential) problem simply with water intrusion into the connectors?

Yes. Power companies know what they are doing. 2 layers of heat shrink are required and you will need a propane torch to shrink it.

 

[LightningBG]

Another problem is you said 3 wire cable. NEC requires 4 wires for sub feeds.

+1

Exactly what popped into my head when I read it.

 

[Kpaige]

You can easily splice and seal the wire 3m makes the splice kits for Xcel energy. You can get cold set so no torch needed. They are pretty cool pull a string and the snap down and seal on each end the have a mold able un cured rubber that seals out any moisture. I sell thousands a yr to them of all sizes google it and you will find them. Now make sure you use the correct wire like others have mentioned.

 

[Kpaige]

Here is a link
http://solutions.3m.com/wps/portal/...ducts/ProductCatalog/?N=5426806+5582688&rt=r3

 

[jhelrey]

and the video...

 

[Dagny]

You will be fine take your time don't over heat the heat shrinks by being in a hurry. If you are worried get some rubber tape and add a few more wraps of that on top of shrinks.

 

[zmaxmotorsports]

Splice it in a hand hole so you can access the splices as needed. Leave plenty of slack in the handhold for repairs. This will give you the best fighting chance by keeping the Splice out of the dirt.

 

[wyliesdiesels]

Another problem is you said 3 wire cable. NEC requires 4 wires for sub feeds.

BINGO

I'm running a 100a sub panel in an extra shop I've built, requiring approximately 125-150' of power wire. I've already bought 1/0 3-wire aluminum cable, and dug a trench to the shop. Problem is, I literally ended up 12-15' short of the panel. I'm pretty much stuck using the wire I have, so I picked up an underground splice kit from a friend who works with the power company.

What potential issues or problems will I run into splicing the power wire running to the shop? It will all be buried, and the splice kit uses **** style compression connectors and two impressive pieces of heat shrink per connector. I would love to have gotten a piece of wire long enough, but that simply isn't an option at this point (and 90% of the cable has already been buried and packed).

Thanks!

EXACTLY what kind of wire did u buy? Sounds like URD.

And as others have said u need 4-wires so youre gonna have to redo this.

 

[pmiranda]

That cold-shrink stuff is awesome... I love hearing about new stuff like that.

 

[Jason280]

Yes. Power companies know what they are doing. 2 layers of heat shrink are required and you will need a propane torch to shrink it.

I'm curious if a heat gun will work, or will I need a propane torch? I have both, so either will be accessible...

Another problem is you said 3 wire cable. NEC requires 4 wires for sub feeds.

Just to be curious, why not 3-wire with a separate ground rod at the panel? Not saying its correct, I'm certainly not an electrician, but I've seen this done quite a few times before to sub panels.

 

[pmiranda]

IIRC old NEC allowed 3 conductors to a subpanel with the neutral and ground bonded and a ground rod for the subpanel. But only if there were no other connections (ie plumbing) between the structures that could result in sketchy grounding.
So if you're ever planning on running water out to the shop as well, that's another reason to do it right the first time and just buy a spool of 4-conductor the correct length.

 

[sberry]

Subpanel is a slang term. This is really a service to a detached structure from an existing service. This used to be acceptable but was changed in 96 maybe?? But anyway the old allowed 3 wire with neutral bonded to the ground at the second panel but this created a lot of problems with alternate pathways for neutral currents.
Its difficult to get past the fact that the ground rod basically does nothing here for the sake of this part of the conversation but there must be a wire pathway with the power conductors back to the main it came from. The earth will not return a fault to trip a breaker, only a wire does this.
The problem really came with the advent of so many more metal interconnections between buildings, gas. water and phone lines. With a bonded N some of the operating currents flow on any metal. For example,,, grounded furnaces in both buildings connected by copper lines, some of the current will flow on this tubing between buildings. Unbonding at the second building allows for the neutrals to be insulated keeping all current on insulated wiring.
Some of the same issues as a fault, some probably flows over it but its short lived with a 4th wire, this wire ran WITH the service conductors delivers a fault directly to service main (others can explain more tech, impedance etc) but or also this wire keeps everything metal on this service connected to it at the same potential.
If a guy has a grounded tool from the house and one from the garage come in contact, or a human is the link there is no potential difference between the 2.
This is kind of a general version.
The rod is there for lightening strikes, we would rather have it diverted there vs carried via the wire back to the originating building or service if possible. There is a bit to do with reduction of step potentials too from ground and now footings that we are standing on.

 

[sberry]

This is probably the number 1 issue with non inspected work or many jobs done by the non licensed handyman, the proper interconnections between panels which have a missing link. Most other errors including human fitting etc will be handled if all this is in place.
This is what an inspector looks for first,,, is the fault return pathway in place and are the enclosures bonded to the grounding system. Other problems are still problems but I have had inspections where he basically looked at this and provided the rest of the workmanship was neat he was on his way.

But only if there were no other connections (ie plumbing) between the structures that could result in sketchy grounding.

We can only assume you know better than this explanation as obviously you know the correct way?

 

[wyliesdiesels]

Just to be curious, why not 3-wire with a separate ground rod at the panel? Not saying its correct, I'm certainly not an electrician, but I've seen this done quite a few times before to sub panels.

Because a grounding electrode and an EGC/ground are 2 different animals. That is a common misconception that they are the same or serve the same function.

NEC code prior to 2008 allowed a 3-wire feeder to a detached structure ONLY if there was no parallel metallic pathways. The reason the allowance was removed is because if the neutral developed a bad connection, the neutral return current could find a different pathway. This is because the neutral bar was bonded to the metal enclosure as well as any other metal that was bonded to the panel. With a bad neutral connection, a shock potential exists!

Now U need both an EGC, tying the main panel to the subpanel AND 2 grounding electrodes. The neutral bar in the sub needs to be isolated and u probably need to purchase a separate ground bar kit.

We get this every week where people are confused on grounding.

Read this article. It will clear up the confusion u have:

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/

Here is a good reference pic:

IIRC old NEC allowed 3 conductors to a subpanel with the neutral and ground bonded and a ground rod for the subpanel. But only if there were no other connections (ie plumbing) between the structures that could result in sketchy grounding.
So if you're ever planning on running water out to the shop as well, that's another reason to do it right the first time and just buy a spool of 4-conductor the correct length.

2008 NEC removed the 3-wire to a detached structure allowance. A 4-wire feeder is NOW required Regardless of whether there is parallel metallic pathways or not.

 

[Jason280]

But only if there were no other connections (ie plumbing) between the structures that could result in sketchy grounding.

This shop is in no way connected to any other structure, and has absolutely no gas or water lines.

 

[wyliesdiesels]

This shop is in no way connected to any other structure, and has absolutely no gas or water lines.

Doesnt matter.

Code no longer allows 3-wire feeds. Read my previous comment above.

 

[Jason280]

I understand that the code has changed, but where is the shock hazard if there is no other metal bonded/connected to the panel?

 

[sberry]

There really isn't per sa if its hooked correctly but as soon as someone adds something there is a problem and its already out of code compliance at the time of installation.

 

[wyliesdiesels]

I understand that the code has changed, but where is the shock hazard if there is no other metal bonded/connected to the panel?

Glad u asked.

As i said, if the neutral connection becomes bad or high resistant and u touch the metal structure or conduit and you have a better lower resistant path back to the source(the transformer), neutral current can flow through u. This happens more than u think.

The code didnt change for the mere sake of changing the code.

Is this being inspected?

 

[Jason280]

Not trying to be argumentative, just genuinely curious. There is no metal conduit, the shop is stick built with 2x6" walls, and the only "metal" is galvalume metal siding and roofing (which is all over OSB). The only source/point of conduction outside of the panel itself would be the wiring going to lights and receptacles.

Oh, and no, this will not be inspected.

 

[Pwrgeek]

Not trying to be argumentative, just genuinely curious. There is no metal conduit, the shop is stick built with 2x6" walls, and the only "metal" is galvalume metal siding and roofing (which is all over OSB). The only source/point of conduction outside of the panel itself would be the wiring going to lights and receptacles.

Oh, and no, this will not be inspected.

Oh man you stepped in it now. The code/inspection Nancys are going to be all over you for this one.

I tend to agree that this is a pretty stupid rule. We all install three wire service drops from the utility to our panels all the time and think this is fine. Hell most of us don't even make up the connections on the utility end and trust it to get done right. How is the feeder from a main panel to a truly detached structure sub panel any different? That all being said the current code requires in no uncertain terms a 4 wire feed with an appropriately sized EGC to be installed in this case. For a multitude of insurance, liability, and legal reasons I would recommend installing it.

 

[Norcal]

A 4-wire feed has been required for a number of code cycles, inspected or not, it should be done correctly.

When power was brought out to the building that my shop was attached to a 3-wire feed run, while it was code compliant at the time I have come to regret that decision as it is getting in the way of adding a phone line & data to the shop.

 

[Pwrgeek]

A 4-wire feed has been required for a number of code cycles, inspected or not, it should be done correctly.

When power was brought out to the building that my shop was attached to a 3-wire feed run, while it was code compliant at the time I have come to regret that decision as it is getting in the way of adding a phone line & data to the shop.

Shouldn't hurt a POTS line, and data (assuming you mean Ethernet) between detached structures should be fiber anyway. If you have a VOIP phone then HomePlug can get you around both of these problems.

 

[Jason280]

Thanks for all the information.

I haven't finished up with the wiring yet, trying to find some extra time...and waiting for the weather to clear up (we are actually getting a little snow right now). As far as the splice is concerned, I believe I am going to enclose it in conduit from the panel. Hopefully I will be able to fit it all in 2" conduit, may be a tight squeeze by the time **** connectors and heat shrink are added. I'll probably go ahead and seal in the back side of the conduit (portion buried with the wire) with either spray foam or some type of silicone sealant...should insure the splice isn't exposed to moisture. Plus, luckily for me, the portion of the wire that is being spliced together is covered by the barn, and won't see any rainfall. If I do end up with some problem at the connection, I can always dig the conduit portion up and start over.

 

[sberry]

If it isn't pulled yet add another wire.

 

[sberry]

I tend to agree that this is a pretty stupid rule.

Yes, the whole code panel is pretty stupid, surprised they didn't consult with you to get it right.

 

[sberry]

Jason, because one doesn't fully understand is all the more reason to follow the directions. You are not the only one but a lot of smart people seem to feel because they don't understand they should do things they way they see it. My phone co has some of those,,, I just don't understand so I wont do it and have invited a lot of lightning strikes in to buildings, not one current installer in my local company, the owner either has ever read 880. The old timers back in the day did it right, they must have had some training vs a few days of ride along with another guy that doesn't know.
I hear this quite often,,, But,,,, I just don't understand,,, followed by,,, but I just don't understand,,, but I just don't understand and I say,,, well follow the instructions then,,,, usually followed by,,, but I just don't understand