Because the code says so? [Linked Image]

Perhaps it's the fact welding tends to remove the required corrosion protection?

Or that improper welding techniques could lead to slag / sharp edges inside the raceway?

I don't have a real answer Steve but to look at another way is why should I weld it when there are so many products designed to support ridge pipe?

Bob

Bob Badger
Construction & Maintenance Electrician
Massachusetts