SUPPORT/ STRAP TO BLOCK WALL

[Alwayslearningelec]

What is that piece that the starp is attached to. I guess that is use when attaching to a block wall??? Thanks.

 

[infinity]

Slang term is a back strap or sometimes called a conduit spacer, it goes behind the raceway. More prevalent on RMC installations than EMT.

 

[qcroanoke]

Slang term is a back strap or sometimes called a conduit spacer, it goes behind the raceway. More prevalent on RMC installations than EMT.

http://www.foxelectricsupply.com/content/products/ProductCatalog.asp?qscategoryId=26183

 

[petersonra]

in technical terms it is called a thingamajiggy.

for emt it is a type 1 thingamajiggy. for rigid it is a type 2. it is important to use the correct type.

 

[Alwayslearningelec]

Slang term is a back strap or sometimes called a conduit spacer, it goes behind the raceway. More prevalent on RMC installations than EMT.

What is the purpose of them? Is it just to keep the conduit from the wall? If so why just RMC for the most part? Thanks

 

[infinity]

What is the purpose of them? Is it just to keep the conduit from the wall? If so why just RMC for the most part? Thanks

It provides a space equivalent to the of the distance from the back of the box to the edge of the KO. The conduit can run straight into the box without the need for bending a box set.

 

[jumper]

in technical terms it is called a thingamajiggy.

for emt it is a type 1 thingamajiggy. for rigid it is a type 2. it is important to use the correct type.

Are thingamajiggys listed? I thought only whatmacallits, doodads, and gizmos were.

 

[petersonra]

Are thingamajiggys listed? I thought only whatmacallits, doodads, and gizmos were.

I challenge you to find anywhere in the code where any of these are required to be listed.

 

[Alwayslearningelec]

It provides a space equivalent to the of the distance from the back of the box to the edge of the KO. The conduit can run straight into the box without the need for bending a box set.

Aaaaahhh...makes sense. So that would be true for all surface run conduits? Thanks.

 

[Alwayslearningelec]

It provides a space equivalent to the of the distance from the back of the box to the edge of the KO. The conduit can run straight into the box without the need for bending a box set.

Aaaaahhh...makes sense. So that would be true for all surface run conduits? Thanks.

 

[hbiss]

Looks to me like that backstrap was used by a hack to keep the strap from falling into the big hole they made for the anchor, not to space the EMT off the wall. I would have use a suitably sized fender washer. Also, maleable backstraps are made to work with maleable straps, not stamped straps like that one.

-Hal

 

[shputnik]

Looks to me like that backstrap was used by a hack to keep the strap from falling into the big hole they made for the anchor, not to space the EMT off the wall. I would have use a suitably sized fender washer. Also, maleable backstraps are made to work with maleable straps, not stamped straps like that one.

-Hal

Pure speculation about the large hole...no?

Personaly I would have liked to see a box offset instead of that or a mini but there is a lot more important things to worry about then a spacer for a ridgid clip.
:?

 

[cadpoint]

The strap is also used to creat an air gap where there are extreme temperature differences.

Cold boxs inside another structure is a prime example, somethings they might be a hot box as well...

 

[dicklaxt]

LOL Lots of guessing going on here guys,,,,,here's the real answer.

I got you youngsters on this one ,,,its called a clampback and was originally intended to be used to keep rigid aluminum conduit off concrete surfaces as the concrete had a lot of chlorine/chlorides,,,,,,,,,,chlorine and aluminum was thought not to mix and would cause a lot of corrosion and concrete failures.Its a long standing running gun battle between the cement folks and the aluminum conduit makers. Its one of those things that will always be around and will probably never be agreed on.

Thats the true start of it all.

The Old Man said that:thumbsup:

 

[masterinbama]

Often specified in wash down areas of food processing plants.

 

[hbiss]

Pure speculation about the large hole...no?

Looks big to me. And sloppy.

I got you youngsters on this one ,,,its called a clampback and was originally intended to be used to keep rigid aluminum conduit off concrete surfaces as the concrete had a lot of chlorine/chlorides,,,,,,,,,,chlorine and aluminum was thought not to mix and would cause a lot of corrosion and concrete failures.Its a long standing running gun battle between the cement folks and the aluminum conduit makers.

Yup, I can believe that. I've found my share of aluminum conduit turned into toothpaste by concrete. I remember one buried run that crossed under a concrete patio. It wasn't even in contact with the concrete and when I went to pull new wiring there was nothing there except a paste. I believe it's the alkali that leaches out of the concrete when it gets wet that causes it. Ever spill lye (Drano) on aluminum? Same effect.

Often specified in wash down areas of food processing plants.

Keeps the conduit spaced off the wall so nothing gets trapped behind it.


-Hal

 

[uwireme]

Was required for a sewage treatment plant so "it" would not build up on top of the conduit after wash down. I did not want to be there when they tested tested it.

 

[Alwayslearningelec]

LOL Lots of guessing going on here guys,,,,,here's the real answer.

I got you youngsters on this one ,,,its called a clampback and was originally intended to be used to keep rigid aluminum conduit off concrete surfaces as the concrete had a lot of chlorine/chlorides,,,,,,,,,,chlorine and aluminum was thought not to mix and would cause a lot of corrosion and concrete failures.Its a long standing running gun battle between the cement folks and the aluminum conduit makers. Its one of those things that will always be around and will probably never be agreed on.

Thats the true start of it all.

The Old Man said that:thumbsup:

THanks...visually(installed) how to you tell the difference between rigid galvanized and rigid aluminum?

 

[dicklaxt]

THanks...visually(installed) how to you tell the difference between rigid galvanized and rigid aluminum?

I don't understand the need for knowing the difference after installation its before that mattered. I can tell the diff in the two by looking,,,,,galvanizing leaves a definite trail by its surface finish/looks while aluminum is smooth.I think I could tap it with a screwdriver and get a duller sound with aluminum.I'll have to go try that,I have some in the garage.

The use of clamp backs were needed on aluminum conduit at the time years ago when the controversy was cooking on high and all the owners were wanting to avert future problems with the possible corrosion.The battle died down somewhat over the years after many studies proved it was not as big a problem as most believed under normal conditions,true enough, it is a real problem when other chemicals get in the mix and clamp backs may or may not be a solution. The manufacturers were all tooled up to make these and didn't want that investment to die on the fine so other uses were found to keep them in the need column as we see it today.

If my memory serves me correctly the original clamp backs were made from malleable iron that was Cadmium Plated and are now Zinc Plated steel as it is used more extensively with other materials.

dick