Buried cable

[manuel casares]

Hello. Two issues. First, I wish to bury 12-2 (with ground) about a foot deep outside and was curious as to how long it would last.

Second, I installed a "smart electrician" gfci (3 pack/$15) and its green indicator stays on whether tripped or not. Outlet seems to work fine. Does the light always stay on?

:>

[Mark Reinmiller]

Hello. Two issues. First, I wish to bury 12-2 (with ground) about a foot deep outside and was curious as to how long it would last.

Second, I installed a "smart electrician" gfci (3 pack/$15) and its green indicator stays on whether tripped or not. Outlet seems to work fine. Does the light always stay on?

:>

You need to read up on code requirements before doing any work. If you are talking about non-metallic sheathing (i.e. Romex) then you need wiring rated for underground use, which would be Type UF or Sunlight Resistant. Standard Type NM cannot be used outside or underground. Properly rated wire should last a very long time.

As for about a foot underground, I believe that 12" is the minimum depth, if protected by a GFCI. Otherwise it is 24" (or maybe 18"). i cannot recall right now.

Regarding the GFCI, read the instructions. Some have lights that go out when tripped, some have lights that come on when tripped. I forget the specific requirements. A light that is on either way would likely be wrong-why have a light at all? And did you really mean 3 for $15? I think the last ones I bought at HD were about $13/each.

[Bill Kriegh]

There are GFCI receptacles that have an "end of service life" indicator that stays on till the device no longer functions correctly, tripped or not. There are also GFCI devices that have an indicator that is on when tripped and some have one that is off when tripped.

The indicators are also in at least 3 colors with no set rule as to whether a certain color means the device is tripped or not.

With new requirements for GFCI protection coming up it would be nice to see a standard.

[michael Rodney]

Hi Manuel,

I agree with everything said so far.

I am in Canada and I think (from the top of my head) the rules here ay 18" for underground cable, but would have to check my code book for the excat wording. The cable cannot be regular indoor Romex. Instead, it must be rated for underground use. I think if less than a certain depth mechanical protection maybe required, but if not only that the cable is rated for underground use. Once again I have to check the code book to be sure of the actual depths.
You may need to check the codes in the Municipality in question to be sure.


For the GFCI there seem to be little or no standard. Some LED on when tripped, others LED on when not tripped. In Canada the cost will vary a bit from about $13 to $18 per unit depending on brand and where purchased. When bought as a value pack 2 or more in a one package the unit cost is generally better.

[William Cline]

Need to check your electric code. Here in California, the direct burial cable depth is 24" unless protected, eg. concrete or conduit.
Check the GFCI for power at outlet when tripped, possibly wired backwards. Otherwise I'd say the light and possibly the gfci are defective.

[Jim Port]

Those California requirements exceed the NEC depths.

[Jerry Peck]

Need to check your electric code. Here in California, the direct burial cable depth is 24" unless protected, eg. concrete or conduit.

William,

Do you have a table for the minimum depths (coverage) of underground electrical wiring?

I'd like to compare it to the requirements of the NEC.

[Jerry Peck]

CEC Table 300.5 Minimum Cover Requirements, ...
(the requirements are basically the same as the NEC, if not exactly the same as the NEC)

If a 120 volt circuit of 20 amp maximum overcurrent protection and has GFCI protection - minimum cover is only 12 inches (minimum depth to top of cable).

If a control of irrigation and landscape lighting of 30 volts or less and installed with UF cable - minimum cover is only 6 inches (minimum depth to top of cable).

[William Cline]

Jerry, Appears that you have found the CEC Table 300.5. Thanks for the expansion. I sometimes give the short answer.

[Jim Port]

Does that mean the minimum depth is not 24 inches as stated above?

[William Cline]

Yes Jim, it would mean that IF the line were protected by an inline GFCI, the burial depth could be as little as 12". Apologies for not posting a complete answer. There are other protection options with varying depths of cover.