Hi:

I would like to bury an electric extension cord that will run about 40 feet from my house to a gazebo. I don't want to hard wire the connection, for a variety of reasons. The primary use will be decorative lights.

My thought is to run the extension cord through a 2 in. pvc pipe, or a flexible conduit, and I need to know how deep I should bury the cord/conduit. Based on a similar question re: hardwiring for a watergarden pump, it appears that 12" to 24" would be the right depth. Can anyone confirm this for me, please?

Many thanks!

There is no approved method of burying an "extension card".
An extension card is not to be used for a permement install.

As answered by Fr. Chuck, you should scrap your idea, now.

What you can do however is use Romex - underground wire (Gray wire). It is much easier to use and does not require the use of conduit. If you have the space on your panel box for another breaker, I would pull your line from the panel to its destination. If you don't like sticking your hands inside the panel box, I would strongly suggest that you get an electrician. Most, I suspect, would either have a ditch witch to dig the trench or can easily rent one for the job.

The trenching should be about 24" deep for a cable that is not inside conduit. At the end of the conduit you must use a water tight junction box and all connections must be inside of junction boxes and easily accessible.

Absolutely correct, extension cord is not allowed as a permanent installation.

"Romex' is incorrect word, as "Romex" cable is a trade name and technically is NM-B cable and is only rated for dry locations indoors.

The proper term for underground cable is "UF", which stands for Underground Feeder. This cable can be buried directly into earth and does not need conduit. If sleeved in conduit, the conduit will need to be of sufficient size to prevent damage to the cable while pulling.


The confusing thing is Romex looks similar to UF cable.

Accuracy is key here.

Extension cords are for "temporary use only" The NEC defines temporary as used for no more than 90 days. Using cords on the ground, not buried, for pumps, holiday lights for no more than 90 days is fine. To answer your question about bury depth of PVC, it is 18" from top of pipe to grade level. I do not recommend you pull an extension cord through it as every conduit will gather water - no matter what. So lets say you pull the cord through, there is water in the pipe which makes the female end drenched with water, you plug it in and could get shocked. You should either use the cord on the ground or consult an electrician to make the installation perminant.
~Matt

TK - My bad!

I apologize for the misuse of the trade name Romex. I realize it is just like saying Kleenex when you really mean tissue.

Question, if you are using conduit, the depth is 18 inches? If you are using UF cable alone, then the depth should be 24 inches, correct?

The correct burial depth for UF [the grey stuff] is 24 inches.

~matt

There are various depths based on conditions.

If the circuit is no more than a 20 amp 120 volt circuit, and protected with a GFI breaker, the cable can be 12 inches deep.

If the circuit is more than 20 amp or 120 volt, or not GFI protected, and is residential one or two family dwelling, it needs to be 18 inch deep.

If not residential, then 24 inch is the correct answer.

This is all found in the NEC 2005 Table 300.5.

See NFPA 70: National Electrical Code®

Found in the Read this First sticky note of the electrical forum. There you will find instructions of how to get to read the actual document.