We recently received an interesting comment on our blog post How Deep Do You Bury Low Voltage Wire? that I thought was worth mentioning in a post of its own.  Patrick has stressed the importance of wire burial depth for landscape lighting before, and obviously it needs to be re-stated as it appears to be a point of disagreement for some people.

The commentator states:

“Not personalizing this is hard because the advice so overly complicates installation of a 12 v system that its likened to mandating the brushing teeth only with the proper sized bristle in tight little circles one at a time, flossing only parallel to the earth and three times daily. The low voltage system is designed to provide a safer voltage carry and can be disrupted by inadvertent digging without serious harm to pets or humans. There is as much need for the pros and the six inch trenches on a 12 volt installation as there is for a monthly trip to the dentist.”

This comment gave us quite a laugh!  In our opinion, burying wire at the proper depth of 6 inches or more, should be better equated to brushing your teeth daily: if you don’t do it as a preventative measure, your teeth (or lighting system) will not last long without serious problems and decay occurring.  For example, in this blog post we mentioned a new client we took on that initially had a lighting system installed by someone who knew nothing about low voltage lighting or the NEC; the system was a dangerous fire hazard.

While we appreciate when our blog readers and those who stumble upon our blog while searching the Internet add their two cents, we wanted to point out that burying wire at least 6 inches in depth is not just our best practice, it is also a regulation under the NEC (National Electric Code) for low voltage lighting.

There is also helpful information on Cast’s website:

http://www.cast-lighting.com/learning/articles/4_1_54

According to article 300.5 of the 2005 NEC Code, low voltage landscape lighting wire needs to be buried to the following depths:

All locations not specified below:  6 inches

In trench below minimum 2″ thick concrete:  6 inches

Under a building:  In raceway only

Under roads, alleys, public driveways and parking lots:  24 inches

Under one- and two-family dwelling driveways and outdoor parking areas and used only for dwelling-related purposes:  18 inches

In or under airport runways, including adjacent areas where trespassing is prohibited:  18 inches

*Note – depth is measured from the top surface of wire to top surface of finished grade or surface material. Where solid rock prevents compliance with these depths, a direct burial raceway can be used, encased in concrete at least 2″ thick on top and extending down to the rock.

We hope this helps clear up any misconceptions about proper wire depth!