Service mast

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Al E.

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My local inspector has referenced NEC 230.28 Service Masts as Supports.
"Where a service mast is used for the support of service drop conductors, it shall be of adequate strength or be supported by braces or guys to withstand safely the strain imposed by the service drop."
He says "Provide support on the service mast. A guy wire support back to the roof since the mast is over three feet above the roof".
Question: How do we determine/define adequate strength? (The mast is a 2" rigid metal conduit). And where do we find the 3 foot reference?

Thanks all
 
My jurisdiction has received guidance from the local POCO on this issue. They provide a service standard that details mast supports, size, and location on a structure. Perhaps your local POCO has the same. Around here, you can generally install 2" RMC 4' above the roof line without additional support as long as two straps are provided and the service drop does not exceed 50'.

Otherwise, this is an AHJ call...
 
I've been using 2-1/2" RMC residential masts for years, because that's the largest hub you can normally get for a 100 or 200 amp meter can. This solves lots of these questions about how sturdy the mast is when you go over 2-1/2 or 3 feet. I still don't go over 3' with a mast anyhow without guying it back. It's all a judgement call and mostly between you and the inspector and the poco.
 
Ours is strictly dictated by the POCO. We are allowed 3 feet with out support, 4 and 1/2 if it is 2.5" IMC. Anything higher must be braced. We always have to have at least 2 straps or clamps, at least 8 inches apart.
They don't care if there is a strap near the box, but our AHJ wants one within 12" of the box, even though NEC I believe says within 3 feet of the box.
 
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