# Installing underground electric properly



## nywoodwizard (Sep 10, 2005)

I had a customer who han an electric boat lift wired,its probably around 50 from the house. My question is : Its a 220 line,should this wire have been installed in some type of conduit for safty reasons ? The fact of the matter is it was not and it also was not wire suitible for burying, simply 10-3 romex for interior use. The reason i know is we clipped it digging some holes in the yard for fencing, nicked a little of the sheathing off and about 1/4" of one hot leads was exposed , i brushed on some wire sealant to protect from anyone touching it and told the customer he should of had it install in some conduit and have an electrician come look at it.


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## Andy in ATL (Aug 17, 2007)

Conduit isn't the biggest problem. The romex is the biggest problem.


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## CE1 (Dec 30, 2005)

nywoodwizard said:


> told the customer he should .............have an electrician come look at it.


Best advice you could of given. :thumbsup: Just wish more people would. It would eliminate a lot of headaches in the long run.

Carry On!


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## goose134 (Oct 10, 2007)

It happens a lot with UF cable. Someone goes digging in the yard to bury a pet or plant a tree and the garage goes out. I've done these for friends and myself and put it in GRC every time. Go ahead and hit it with a shovel, it's not going anywhere. Plus you don't have to dig as deep!


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## gravtyklz (Dec 24, 2005)

goose134 said:


> It happens a lot with UF cable. Someone goes digging in the yard to bury a pet or plant a tree and the garage goes out. I've done these for friends and myself and put it in GRC every time. Go ahead and hit it with a shovel, it's not going anywhere. Plus you don't have to dig as deep!


You're right about the shovel part. But if someone is using a machine to dig....unless they're being extremely careful they could easily crush through pvc conduit.


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## Celtic (May 23, 2007)

gravtyklz said:


> You're right about the shovel part. But if someone is using a machine to dig....unless they're being extremely careful they could easily crush through pvc conduit.


GRC is not PVC....









GRC (Galvanized Rigid Conduit)












PVC (aka RNC ~ Rigid Nonmetallic Conduit)


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## gravtyklz (Dec 24, 2005)

Celtic said:


> GRC is not PVC....
> 
> 
> 
> ...


I completely missed the GRC part. 

I was thinking conduit in general....and pvc in general.


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## Magnettica (Dec 19, 2006)

The good thing about the ridgid is that you only have to down 6" from grade.

The bad news is that it's a bit more expensive and harder to bend.

IMO, if someone else is digging the trench I'd use the PVC.

Using UF for this particuliar application IS NOT the way to go.


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## Celtic (May 23, 2007)

Magnettica said:


> The good thing about the ridgid is that you only have to down 6" from grade.
> 
> The bad news is that it's a bit more expensive and harder to bend.


...more bad news is that in order to get that 6" depth you'll also need 2" of concrete.


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## nywoodwizard (Sep 10, 2005)

Does the metal conduit or couplings underground get sealed? If you use any type of conduit does the wire type still matter since its not exposed to the elements or sun light ? I may as well learn something while i'm here


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## wayni (Nov 12, 2007)

nywoodwizard said:


> Does the metal conduit or couplings underground get sealed? If you use any type of conduit does the wire type still matter since its not exposed to the elements or sun light ? I may as well learn something while i'm here


*NEC Article 300.5 (B)*

*Listing. *Cables and insulated conductors installed in enclosures or raceways in underground installations shall be listed for use in wet locations.


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## Celtic (May 23, 2007)

nywoodwizard said:


> Does the metal conduit or couplings underground get sealed?


Just tighten them up..wrench tight is nice.



nywoodwizard said:


> If you use any type of conduit does the wire type still matter since its not exposed to the elements or sun light ?


Sure the wire type matters...sun is not the enemy here...water is.
Conductors with a "W" in their insulation type would be allowed, ie ~ THHN/THWN allowed, Romex (NM-B) not allowed.


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## nywoodwizard (Sep 10, 2005)

Celtic said:


> Just tighten them up..wrench tight is nice.
> 
> 
> 
> ...


My thirst for electrical knowledge has been quenched :thumbsup:


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## BoydS (Dec 7, 2006)

GRC (Galvanized Rigid Conduit)

Gosh, and I always called it RGS conduit (Rigid Galvanized Steel).


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## Magnettica (Dec 19, 2006)

Celtic said:


> ...more bad news is that in order to get that 6" depth you'll also need 2" of concrete.



I disagree. The OP says this boat lift is 50' from his house. So unless he has an airport runway or a street in his backyard I think he's ok going down 6" without the concrete.

Table 300.5 (All Locations Not Specified Below column)

What do you think?


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## Celtic (May 23, 2007)

BoydS said:


> GRC (Galvanized Rigid Conduit)
> 
> Gosh, and I always called it RGS conduit (Rigid Galvanized Steel).


I got sick of being yelled *at* for saying RGS  ...
".RGS is not in the NEC....blah blah blah...angry words...more angry words...."
Ok, so get over it already, I says to man.
...followed by more angry words.
On the plus side, I did _almost_ get the man to burst a very large pulsating vein in his forehead :laughing:


I was sooooo tempted to ask for a "MIGB" :whistling ...but it was payday :thumbsup:


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## Celtic (May 23, 2007)

Magnettica said:


> What do you think?


I think it said 120v ckt ....opps


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## Magnettica (Dec 19, 2006)

Celtic said:


> I think it said 120v ckt ....opps



The OP said it was a "220 line" so note #4 of Table 300.5 is out.

I'm not sure when to use concrete.

The last time I used ridgid in residential was a couple of years ago for a halogen flood lamp shining up on a tree. 6" deep, no GFCI protection.


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## goose134 (Oct 10, 2007)

> ...more bad news is that in order to get that 6" depth you'll also need 2" of concrete.


I'm not sure I know about this one. Is this a location specific requirement, or a general rule? Also, another sweet touch on the rigid (especially in concrete) is copper pipe dope. KOPR shield I belive is the name of it. Helps against corrosion on the weakest part (especially if you cut your own threads).


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## Magnettica (Dec 19, 2006)

I've used a threading machine less than half-a-dozen times.

I use threadless couplings instead and pull a seperate EGC just in case.

Not that there's anything wrong with threading the pipe, it's just that it's a skill that I'm not too good at.


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## Celtic (May 23, 2007)

Magnettica said:


> I've used a threading machine less than half-a-dozen times.
> 
> I use threadless couplings instead and pull a seperate EGC just in case.
> 
> Not that there's anything wrong with threading the pipe, it's just that it's a skill that I'm not too good at.


This:









and this:










...but preferably these:





























Separate the men from the monkeys :thumbsup:


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## constructionldr (Nov 14, 2007)

I handle the wiring of alot of boat lifts in Lake of the Ozarks in MO. While some peeps like to save money and use uf ...its not a good idea. Believe me with all the new gadgets and tech. iinvisi fence/ fiber optic etc...we use pvc, bell ends/couplings and glue. Nice moisture barrier no concrete and go. We do use rigid in rocky conditions (where ground is too rocky to dig appropriate depth. PVC is the key

Just my two cents


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## goose134 (Oct 10, 2007)

I'm still curious about the 2" concrete fill. Is this a location specific code, or what? Aside from fire rating your FCP, fire pump and affiliated raceways, I've never heard of having to put GRC in concrete.


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## Magnettica (Dec 19, 2006)

The 2" concrete requirement is used for specific applications. 

For instance, service entrance conductors that enter a building underground, but not at the point of entrance. Inbedded in the 2" of concrete they are considered to be outside the building. 

230.6 (1)(2)


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