bending service entrance

[George Stolz]

It's my job and a the final installation is a reflection on me and my work, not just my apprentice's. I'm nice to them and not an ***, but I let them know what I want and what I don't want.

Amen.

Just as when I was an apprentice, I was in a shop with 5 JW's and I knew what each of them wanted and expected.

Ugh. I'm glad you stuck it through! I floated around a bit for a while apprenticing, and it was the pits, especially with a day with a "vocal guy" (***).

 

[dnem]

When contractors bring their feed in thru an expansion joint coupling in the conduit, they need to have expansion loops in the wire.

Many installations with expansion fittings do not require extra wire. The conduit is doing the expanding not the conductors.

It all depends on if we're talking about ambient thermal expansion or ground movement. If it's 300.5(J) ground movement, we require expansion loops, if an expansion joint is used.

But there are some situations where we don't require an expansion joint for ground movement.
I copied our list

Where Not Required
On any of the following:
1] On conduit trade size 1 inch or smaller
2] On risers supported by poles, stakes, or stands that are not attached to building structures
3] On risers not attached to horizontal runs
4] On risers attached to horizontal runs that are 40 inches or deeper from final grade
5] On risers that come up thru a concrete slab

David

 

[JohnE]

David,

How much of a loop do you require on the conductors? Enough for the ground to move 1",2", or more? I don't use these loops with an expansoion coupling, but do put enough "bend" to allow for about 2" of ground movement. I'm talking about when we enter a plain meter enclosure in a typical residential underground service. Meter only, not meter/ main.

John

 

[infinity]

Where Not Required
On any of the following:
1] On conduit trade size 1 inch or smaller
2] On risers supported by poles, stakes, or stands that are not attached to building structures
3] On risers not attached to horizontal runs
4] On risers attached to horizontal runs that are 40 inches or deeper from final grade
5] On risers that come up thru a concrete slab

Is this list from a local requirement?

 

[dnem]

Where Not Required
On any of the following:
1] On conduit trade size 1 inch or smaller
2] On risers supported by poles, stakes, or stands that are not attached to building structures
3] On risers not attached to horizontal runs
4] On risers attached to horizontal runs that are 40 inches or deeper from final grade
5] On risers that come up thru a concrete slab

Is this list from a local requirement?

It's not a local code. We don't have any local additions to the code. It's the decision of our chief ESI on interpreting the phrase in 300.5(J) "Where direct-buried conductors, raceways, or cables are subject to movement by settlement or frost ....."
Where are they subject to ground movement ? The chief made the call. Number 4 is based on the freeze depth in our part of the country.

The last part of 300.5(J) covers the wire loops "..... cables shall be arranged so as to prevent damage to the enclosed conductors or to the equipment .....". As far as how much of a loop is needed, I think it's more of how much room there is in the enclosure. I would doubt that most enclosures have room for more than 4 inches of extra wire. The "Edison heart" in the meterbase or the "ears" in the top of the panel probably only have about 4 inches of slack to give up.

David