indoor-type electrical power wiring buried under lawn-- how long will it last?

Don't let the city inspector find this, you'll be digging it up with a fine to boot.

Underground AC cables need to be rubber coated, PVC does not count.

So, choose you poison.

donald

I don't think the spiral armored cable is rated for direct ground contact. Not only will the galvanized steel shield rust off, giving you an unsafe ground path back to the panel, the wire insulation is not rated for the moisture of direct burial, and will eventually (if it hasn't already) develop current leaks that will spin your meter.

I think I would replace it with type 12-3-UF with ground (rated for direct burial). This would allow a current rating of 20 amps, but lower voltage loss for a 15 amp circuit, but also would allow expansion to a full 240 volt circuit, if you ever decide to put something larger, like a compressor, in the garage. The cost of the wire is trivial compared to the cost of the slot to lay it in.

I cannot believe this complies with your city codes.

Oh, I'm 100% sure it doesn't. But what I'm trying to do is satisfy my curiosity about why a PVC coated wire would ever develop a current leak just because its in contact with moist soil.

Obviously, if/when I go to sell my house I would have to replace this, or fully disclose it. Unfortunately for me, I bought this house in an estate sale, so there was no living owner to provide me with any disclosures. live and learn...

It won't. But BX isn't designed to be run without the sheath and that won't survive.

We used to either run plastic conduit or we ran Romex 2 feet deep in sand and covered it with cement planks (approved where I was).

The proper way over here is to use UF and install it according to code.

Replace it with schedule 80 gray PVC electrical conduit at the depth required by your local building inspector. That mess you have now could develop leakage to the soil, and have a high voltage gradient that could kill someone.

Don't worry too much you can place cables in water and still comply with the code! A different story though.

The metal protection is good as it gives mechanical protection and should satisfy your local regulations. I assume the metal shielding is around the 2 plastic wires.

In case you don't have metal protection around the plastic. You need a metal slab or plate on top of the wires or a curved metal tile.

The Plastic should be at least PVC R2 or a higher rating. If it is Rubber at least G7 rubber. (Older ones mostly had G5 rubber I noticed).

An unshielded ground wire is pretty normal and agrees totally with the code.

Andy

It depends on soil conditions and the PH, it could dissolve the insulation within a year or so, and once the integrity of the insulation is breached, the conductor will corrode at an accelerated rate. The 6" depth is okay for low voltage but universally out of spec for line voltage which is usually 18". If all you have in the garage is lighting then a quick fix would be to convert to low-voltage and replace the BX with a direct burial UF type of bundle which can *possibly* be pulled through the existing conduit.

Obviously, there's the correct way to do this, and then the way it was actually done.

If you're not going to correct this now, and you don't intend to disable the circuit, perhaps you could at least install a GFCI breaker on this branch circuit....?

-mpm

Thats probably the best idea. If/when the insulation is ever breached, the GFI will kick out before someone gets hurt, and the problem won't go undetected spinning my electric meter

Of course, you know to put it at the entrance panel end, not the garage end, right?

Cheers! Rich

Total rubbish.

The GFCI receptacle in the garage does absolutely nothing to ameliorate the problem. The receptacle can protect from a problem in a device plugged into it, or from a problem dowenstream of itself. It can do nothing to protect from a problem between itself and the power source.

The only right answer is to replace with new, up to code wiring, or just disconnect (at the house end) and abandon or remove the old stuff. Per the US national code "up to code" with regard to burial depth, means, in general: Direct burial UF cable without a raceway must be buried at least 24" deep. If you use rigid metallic raceway listed for underground installation, it must be buried at least 6". If you use non-metalic raceway you have to go 18". You can reduce that to 12" if you GFCI protect the circuit, and if the circuit is no more than 20 amps.

There are specific locations (for example under driveways) with different rules, per 300.5 in the National ELectrical Code

Ed

At last, someone got out the code book.

I was going to do it myself, but I've been trying to digest a nasty-worded contract this afternoon.

So I sent it to my son-in-law ;-)

...Jim Thompson

There are still local codes to worry about. Some soil conditions make the use of metalic conduit in violation of the code because the soil PH.

Very crappy

Andy

Hey hey.

Your answer Mr. Edge complies with the Central European directives which may seem crappy compared to the ones given by Mr. Eddy.

Klaus