# Here's how we back brace a tall riser/mast



## 220/221

POCO makes us back brace 2" IMC over 36". I hate doing it but sometimes we need some extra height to clear an obstacle.

Braces are 3/4" EMT hammered flat and drilled. Braces must be bolted through the rafters. If there is enough room in the attic space it's not too bad. 

I generally I locate the rafters from above with long drywall screws then drill down. 

This one had some room in the attic so I drilled up, tapped in a carriage bolt, bolted down a 4s blank as a washer and bolted the brace to the remaining stud.











The hole is drilled exactly the same size as the bolt for a tight fit and the blank is caulked and bolted down snugly to the shingle to (hopefully) prevent a leak. 

The 4s cover does look a little hacky so I am looking for something as big to take it's place.....maybe something galvanized. I tried washers before but they sucked into the shingle too much and I ended up splooging caulk all over them to seal them up.
.


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## RePhase277

Use your tin snips to cut the corners off the blank, like an octagon. It would look spiffy then.


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## Speedy Petey

I say that's a decent job. 
Why so overbuilt though? We just use wire rope straight back to an anchor. Are you required to triangulate that way?

You also forgot the rubber on the roof boot....not that it rains there.  :laughing:


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## Dennis Alwon

Nice looking job and a great idea. I always just used steel cable but I like your way better.


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## 220/221

> Use your tin snips to cut the corners off the blank, like an octagon. It would look spiffy then.


You think tin snips will cut a blank cover???





> You also forgot the rubber on the roof boot....not that it rains there


We dont use rubber boots here. If it leaks it just runs down to the top of the exterior panel anyway. ...and it IS raining today :thumbup:



> Why so overbuilt though? We just use wire rope straight back to an anchor. Are you required to triangulate that way?


POCO specs. two 3/4 EMT braces, thru bolted, 45 degrees.


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## drsparky

Is the riser EMT?


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## B4T

Some EC around here use shallow kindoff.. looks like it sounds :no:


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## crazymurph

Do you paint it when you are done? A couple coats of Cold Galv would do the trick. I have seen my buddy use a bracket like that to support a Class A chimney. He was using a kit that he bought from his supplier and the kit used 3/4 EMT. He now makes his own and saves money.


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## 220/221

> Is the riser EMT?


IMC




> Do you paint it when you are done?


:no:


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## RePhase277

220/221 said:


> You think tin snips will cut a blank cover???


Absolutely:thumbsup:


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## B4T

220/221 said:


> You think tin snips will cut a blank cover???


 
There is no way you could cut the 4" blank with tin snips and make it look good IMO

Maybe a plumbing supply might have a round flange you could use


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## leland

Nice looking job.:thumbsup: Solid and secure. keep the POCO happy.

But IMC- I would think 'Rigid' nothing less.
We don't get a lot of those installations here, Usualy a good solid side of the house to secure to.

I have seen water cause a lot more damage than electrical in the past.

I would definitely have put a 'boot' on the riser.

After all that- what, maybe a 35% inrease on a service price?

After all... I aint a roofer, I sub that out.


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## McCaa

We do the same thing here in California. However, instead of EMT we use 3/4" IMC for the braces and IMC for the riser too. You think his is overbuilt, you should see mine!


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## 220/221

.


> But IMC- I would think 'Rigid' nothing less


 
I haven't even seen a stick of rigid in twenty years.:laughing:




> I would definitely have put a 'boot' on the riser.


I put a roof jack on it, just not a rubber one. There is like a 1/64" clearance which is caulked.

The panel is outside and the IMC runs into a factory hub.


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## NolaTigaBait

The only place that stocks rigid is Lowe's . The supply house is all IMC. Quite a bit heavier.


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## 480sparky

Which of the 3 black wires is the noodle? :001_huh:


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## RePhase277

Black4Truck said:


> There is no way you could cut the 4" blank with tin snips and make it look good IMO
> 
> Maybe a plumbing supply might have a round flange you could use


Simply untrue. A good pair of snips will cut easily and cleanly through a 1900 blank. Try it sometime. I made some large KO seals from blanks just the other day.


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## 480sparky

InPhase277 said:


> Simply untrue. A good pair of snips will cut easily and cleanly through a 1900 blank. Try it sometime. I made some large KO seals from blanks just the other day.


 
I've never tried to cut a blank cover, but mine will easily cut fender washers.


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## user4818

480sparky said:


> Which of the 3 black wires is the noodle? :001_huh:



The one with white tape on it.


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## 480sparky

Peter D said:


> The one with white tape on it.


 
You must got better peeper's n me, sonny.


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## user4818

480sparky said:


> You must got better peeper's n me, sonny.


:detective:


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## 480sparky

Peter D said:


> :detective:


Damn punk kids these days!


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## crazymurph

NolaTigaBait said:


> The only place that stocks rigid is Lowe's . The supply house is all IMC. Quite a bit heavier.


 
IMC is lighter and stronger than GRC "rigid". GRC is more malleable which makes it more easy to bend and less desirable for a riser mast.


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## TOOL_5150

I sure am glad I dont live where it snows. We are allowed to go much higher with a @" mast wwithout any backbracing.

~Matt


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## John

crazymurph said:


> IMC is lighter and stronger than GRC "rigid". GRC is more malleable which makes it more easy to bend and less desirable for a riser mast.


Wait a minute....
Where pray tell did you get this piece of information?:001_huh:


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## mattsilkwood

crazymurph said:


> IMC is lighter and stronger than GRC "rigid". GRC is more malleable which makes it more easy to bend and less desirable for a riser mast.


what?


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## crazymurph

John said:


> Wait a minute....
> Where pray tell did you get this piece of information?:001_huh:


 
Have you used either of the materials? If you were to use both side by side you would see the difference.


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## Shado

http://www.alliedeg.com/pdf/atc_1702_imc_12p_guide.pdf

Sounds odd....but...this seems to confirm it. :001_huh:

Look at page 8...


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## macmikeman

Bender springback values on the 555 bender confirms that IMC is more resistant to bending.


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## ampman

do you make the final connection and if so do you use a service wedge


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## 220/221

> I've never tried to cut a blank cover, but mine will easily cut fender washers.


To fit them in Unistrut? :thumbsup:





> I sure am glad I dont live where it snows. We are allowed to go much higher with a @" mast wwithout any backbracing.


Heh heh, I don't think snow is the issue.:laughing:




> do you make the final connection and if so do you use a service wedge


 
POCO does the connections and they do use service wedges. 

We are not even allowed to look at it.....although on this one I temp'd a GFCI recep for a day so I didn't have to listen to the carpenter's generator. :jester:


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## 480sparky

220/221 said:


> To fit them in Unistrut? :thumbsup:......


Absotively posilutely!


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## cdnelectrician

Tin snips will cut through a blank cover no problem!


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## Magnettica

Sorry, but that bracing with the 1900 blank plate is going to leak water into the attic.


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## ampman

220/221 said:


> To fit them in Unistrut? :thumbsup:
> 
> 
> 
> 
> 
> Heh heh, I don't think snow is the issue.:laughing:
> 
> 
> 
> 
> 
> POCO does the connections and they do use service wedges.
> 
> We are not even allowed to look at it.....although on this one I temp'd a GFCI recep for a day so I didn't have to listen to the carpenter's generator. :jester:


 that noise gets old after a while


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## 220/221

> Sorry, but that bracing with the 1900 blank plate is going to leak water into the attic.


 
That's always been my biggest concern. I'm not sure how to penetrate the roof, thru a rafter without somehow comprmising the integrety of the roof.

This installation is the best I have come up with. Any sugestions will be appreciated...or at least considered.:laughing: Maybe I should just glob on more sealant?

I drilled a 3/8 hole and used a 3/8 carriage bolt from the bottom so the fit was tight. I applied a liberal amount of caulk/sealant around the bolt, under the blank and tightened down a nut till the sealant squeezed out and the blank was tight to the shingle. I then slipped the brace over the protruding stud and nutted it on.

I figured that when the reroofed, they could unbolt the braces, roof around/over them and reattach them. If I globbed sealant all over it, it would make it difficult to do this.

I am open for suggestions.


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## Bob Badger

NolaTigaBait said:


> The only place that stocks rigid is Lowe's . The supply house is all IMC. Quite a bit heavier.


What kind of lame supply house do you go to? :blink:


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## user4818

Bob Badger said:


> What kind of lame supply house do you go to? :blink:



The one I go to has been running out of basic items like deep 4" squares lately.


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## 480sparky

I can well imagine the streaks of rust that will be spreading across that roof in a couple years.

If that were my house, I'd demand it be redone in a manner that would not leave rust-stain streaks down the shingles.

Not to mention that in a few years, there will be very little left of that blank cover. What's the point of installing a service intended to last 50 years if one component will only last a tenth of that?


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## user4818

480sparky said:


> I can well imagine the streaks of rust that will be spreading across that roof in a couple years.
> 
> If that were my house, I'd demand it be redone in a manner that would not leave rust-stain streaks down the shingles.
> 
> Not to mention that in a few years, there will be very little left of that blank cover. What's the point of installing a service intended to last 50 years if one component will only last a tenth of that?


Maybe in Eye-O-Wuh, but I don't think rust streaks are much of a problem in the desert.


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## LJSMITH1

220/221

I would put a boot on that mast penetration since it is going through a roof cavity. The water running down the mast will not always stay on the mast. It may run down the inside of the flashing onto the roof sheathing and then into the cavity. The soffit is solid, so any water that does get in, will also stay in and cause rot or mold. 

As for the EMT supports, I would have used Stainless lag eyes with asphalt sealant around the base and stainless or galvanized cable. Limited or no rust to worry about and no real fabrication. Antenna Mast installers did this a lot in my area and you can barely see the guy wires.










Other than that, nice install!


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## 220/221

> I would put a boot on that mast penetration since it is going through a roof cavity.


 
It* has* a roof jack. If you mean a rubber boot, they are just not used here often.





> If that were my house, I'd demand it be redone in a manner that would not leave rust-stain streaks down the shingles.


No rust streaks here. Galvanized metal hold up well here unless it's underground.




> As for the EMT supports, I would have used Stainless lag eyes


Not allowed by POCO here. Must be bolted thru the rafter/framing.


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## LJSMITH1

220/221 said:


> Not allowed by POCO here. Must be bolted thru the rafter/framing.


What about a stainless eye bolt with a nut and a couple of stainless washers bolted through the framing?


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## 220/221

Wire isn't allowed. As goofy as it sounds, POCO specs say 3/4 EMT :jester:


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## LJSMITH1

220/221 said:


> Wire isn't allowed. As goofy as it sounds, POCO specs say 3/4 EMT :jester:


 
Wow...live and learn. I woudn't think that they would be so picky.:thumbsup:


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