Thread: Flashing for square service mast on comp shingle roof?

Anyone ware of a product intended to do this - like the EMC mast flashings, but for a square mast?

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My first question is: What is the square mast made of and is it approved and listed for use as an electrical riser mast?

It would first and foremost have to be a listed raceway, and I am trying to recall a square listed raceway approved for use by the NEC ... but am coming up blank.

If it is not a properly listed raceway, or the raceway is inside of a square outer covering, then I would have to question "Why?" is it over the raceway and how is it secured to the raceway and how is the raceway now properly supported and secured.

Only if the square mast ends up being approved for use is there a need to figure out how to flash it, but I suspect that part of the problem will go away when the firsts part(s) mentioned above are addressed.

#1 Master Flash Square Tube Retrofit Flashing
Fits 2-1/2" to 4" sq.

Originally Posted by Jerry Peck

My first question is: What is the square mast made of and is it approved and listed for use as an electrical riser mast?

It would first and foremost have to be a listed raceway, and I am trying to recall a square listed raceway approved for use by the NEC ... but am coming up blank.

If it is not a properly listed raceway, or the raceway is inside of a square outer covering, then I would have to question "Why?" is it over the raceway and how is it secured to the raceway and how is the raceway now properly supported and secured.

Only if the square mast ends up being approved for use is there a need to figure out how to flash it, but I suspect that part of the problem will go away when the firsts part(s) mentioned above are addressed.

"First and foremost .. a listed raceway" is not always true. A wood service mast will not be a raceway. According to an inspector here in BC, a square wood service mast may be acceptable if a standard metal pipe mast (such as a CSA certified mast kit) cannot provide the required roofline or roadway clearance. Usually one or more guy lines are required for the wood mast. The service conductors are in a service cable or run in a conduit, in both cases fastened to the mast. I have seen such masts locally mostly on small old bungalows. The preferred location for a square wooden mast, or any mast for that matter, is on a gable end so there is no roof penetration to flash, but if the mast penetrates a roof overhang then there should be flashing. A mast through a roof is more vulnerable to damage from sliding snow and ice than a gable mounted one. The inspector also said that some inspectors have taken the position that a wooden service mast is part of the building structure and that the timber size and fastening must be approved by the building inspector, as those are not subject to the Electrical Code. Only the location and height of the service mast are subject to the Electrical Code, as is all the electrical stuff fastened to the mast.

The retrofit flashing mentioned in a different post is nice but will not fit a 6 in x 6 in size mast. A mast smaller than that (e.g. 4 in x 4 in) would likely not be strong enough - I do not recollect seeing any.

Originally Posted by Frank Norman

"First and foremost .. a listed raceway" is not always true. A wood service mast will not be a raceway.

Ummm ... a wood mast is ... of course, not a raceway, in which case it would not be going up through the roof as the service entrance conductors would not be going through the attic overhang area.

The service conductors are in a service cable or run in a conduit,

Correct, and flashing that conduit through the roof is what is being discussed here, at least that is my understanding of the discussion.

I've seen pitch pockets installed on comp roofs around square masts once in awhile. Not a common item around here.

Originally Posted by Michael Thomas

Anyone ware of a product intended to do this - like the EMC mast flashings, but for a square mast?

IIRC, RGS and not EMC was the minimum in your area for OH service mast, 6' H max on sloped roof; steel channel supporting mast application to be secured to ext. structural wall for support, not roof structure. Plumbing or vent square tube alum/edpm wouldn't be mast-approved flashing alum. would deteriorate quickly w/exp to galv steel & copper treatment granuals on comp roofing esp with acid rain/polution envir NE Ill. Many of the PT posts if still allowed for support of other than temp connections, not compatible with steel - galv or not quick deterioration esp. in acid rain/polution envir. Uknwn if lead formwork still allowed in the cty.

Might want to dbl check the up-to-date ultility regs/reqs and the muni adoptions/more-restrictive ammendments.

Originally Posted by Jerry Peck

Ummm ... a wood mast is ... of course, not a raceway, in which case it would not be going up through the roof as the service entrance conductors would not be going through the attic overhang area.
.

I have seen a wood mast, about 3-4', at the peak and end roof edge with the service entrance conductors to a conduit on the side of the house. The mast went at least it's exposed length or more into the framing for support. It used custom flashing to match the peak with a flashed cap.

Originally Posted by Rich Goeken

I have seen a wood mast, about 3-4', at the peak and end roof edge with the service entrance conductors to a conduit on the side of the house. The mast went at least it's exposed length or more into the framing for support. It used custom flashing to match the peak with a flashed cap.

How were the service entrance conductors run down that mast and into the structure to the service equipment - down through the roof and the flashing?

Ever try to flash a piece of wood so that it was waterproof?
Wood takes in water, checks and cracks, rots, etc., and makes it extremely difficult to get any type of waterproof penetration through the roof, maybe for a short while, but they do leak, and will leak, due to the nature of the wood itself.

Originally Posted by Jerry Peck

Ummm ... a wood mast is ... of course, not a raceway, in which case it would not be going up through the roof as the service entrance conductors would not be going through the attic overhang area.

Frank is from my side of the globe, so he knows that square wooden masts do go thru roofs, especially older hip roofs, and the service conductors do as well. The mast is bolted to an exterior wall or framed up inside the wall cavity.
The CEC does not allow the service drop to cross the roof, so a mast is often required. The power company will attach a bridle to the lines between poles to get an approach to the house that stays clear of the roof. Most wooden masts are flashed better than this one. The craftsman would insert flashing into a saw kerf, a shallow saw cut.

Originally Posted by Jerry Peck

How were the service entrance conductors run down that mast and into the structure to the service equipment - down through the roof and the flashing?

Ever try to flash a piece of wood so that it was waterproof?
Wood takes in water, checks and cracks, rots, etc., and makes it extremely difficult to get any type of waterproof penetration through the roof, maybe for a short while, but they do leak, and will leak, due to the nature of the wood itself.

Geez Jerry..... I can just see you on the dunes and saying to Orville----"It's just won't fly!"

The mast was in good shape, well taken care of, at least 20 years old. As I said, the mast was on the peak at the end of the roof, the conduit came up the side of the house and the head ended at the peak. The power company attached to the drops with about 2-3' loops. They were happy.
The post was flashed on the roof with the counter flashing cut into the post.

Originally Posted by Rich Goeken

Geez Jerry..... I can just see you on the dunes and saying to Orville----"It's just won't fly!"

Actually, Wilbur told me to "Release the rope and stand clear!"