Calculating How Deep to Bury Outdoor Electrical Wire

Planning of setting up outdoor electrical wiring for installations that require electrical connectivity features? Then, go through our blogs to stay of what are the latest upgradations in the field of electrical wiring and safety Installations.

Myriads of electrical outdoor wiring need to be done for the operation of water pump, motor, luminaries, and other apparatuses. For all these purposes, its wiring part can be done in two ways – overhead or deep below the ground. This blog would focus on the wiring run in a below the ground trench and learn on how Deep to bury them. Wire burial is an important factor where some cables need little digging while some need to be buried deep underground as per the Pertaining code for burial depths.

You must know that there are several local and municipal laws and regulations that apply on outdoor electrical wiring and cable burial. Before planning, you must also approach the local utilities so they can mark and have the knowledge on where the underground utilities lie on your property. Moreover, some typical electrical installations and cable burials would require construction and electrical permit, so apply for it if required in your municipality.

1. Electrical service cable direct burial- They are underground feeder cable specially designed and manufactured with properties that make it burial possible directly underground without any extra conduit protection. These cables are placed in underground trench constructed at a depth of 24 inches. UF cables buried this far underground have least probability of getting damaged or disturbed even when they are without any shielding. It has thin insulation layer and waterproofing cover providing high mechanical properties. This is a good option for people looking for easy installation of cables without conduit.

2. UF Cables installed above the ground- Although UF cable are designed, rated and approved to be buried underground, you can also use it above ground after getting checked from the electrical inspected. In case you need the electrical cables to be run partially under the ground and the rest above the ground, but you need to avoid splicing the burial cable then the option to run the UF cable full length above the ground. But, you must install the UF cable above the ground only inside a conduit as otherwise they may be subjected to damages from external factors.

3. Enclosing electric wire in PVC Conduit- As per the National Electric Code (NEC), the permissible burial depth of electric service wire encased in any rigid or non metallic covering such as PVC conduit shall be 18 inches. The proper depth trench made for laying cables enclosed in PVC conduit can effectively keep them protected against the danger of being damaged or disturbed by normal digging. But no cable or shielding ensures 100% protection from digging by trench diggers or backhoes.

4. Use of rigid conduit- Rigid conduit system offers good protection from external forces, moisture, etc. when buried at a shallower depth. According to NEC, rigid conduits are durable to protect sensitive cables and circuits when buried it at a depth as shallow as 6 inches.

5. Use of Flexible Metal Conduit- For irregular and curved structural profile, you may use flexible metal conduit so that they can be easily bent at the job site and the excessive number of fittings/ connections can be avoided. In this case you just need to take care that the flexible metal conduits are watertight.

This was a gist on cable burial rules; keep learning more about electric safety via our blogs. Moreover as an industry professional, you can get adequate knowledge on the well and basic standards about external and internal electric protection, structural lightning protection, surge protection, maintenance free earthing system, and lot more from our websites.