PVC and and footers

[Bill Turax]

Typically when we install an outside line, say a feeder from an existing single family hole to a detached garage for a sub-panel, we install the circuit in PVC conduit 18" deep, 20" to be safe.

there are a few occasions where the existing footer is less than 18" deep. When we encounter this we take the hammer drill and chip it away as needed to get to our 18".

we recently did this and when the inspector looked at our trench he noted that we did not need to do that because the code allows you 18 horizontal inches to get 18 inches deep when exiting the structure. I tried to look up this code in 300.5 but found nothing.
anyone ever heard of this or know where the exact reference is.

 

[infinity]

Look at Note #3 Table 300.5.

 

[Cow]

The article Rob pointed to makes no mention of 18", that must be your inspectors rule of thumb.

In the past, I've simply used two 45's on our stubups, rather than a 90 to clear obstructions like a footing.

 

[Dzboyce]

I had to go out to my pickup and grab my code book. I don’t get where 309.5, note 3 allows 18” to get to minimum cover depth. Seems to me that it comes down to interpretation and common sense. I realize that those don’t necessarily go together.

 

[infinity]

The article Rob pointed to makes no mention of 18", that must be your inspectors rule of thumb.

I agree.

I was simply pointing out that you do not need to chop out the footing which likely creates building code issues.