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Securing 3/8 rod to overhead concrete #204082
11/09/11 02:29 PM
11/09/11 02:29 PM
S
sparkync  Offline OP
Member
Joined: Oct 2002
Posts: 830
NC
Have a job tying in a big chiller. They moved out the old one and brought in a new one. There are 2 sets of 3" emt fed from overhead with (3) 500 MCM in each conduit and a ground in each one. I'm going to have to shorten the pipe overhead and re-feed them down to the new chiller. There are no supports right before it will have to go into the new chiller. I got some 3/8 rod and plan on using some unistrut to hold it, but am having a problem getting the right anchor bolt to go into the concrete overhead. I got a 3/8 sleeve type bolt and some 3/8" rod couplings, but the problem is the threaded part of the sleeve is 5/16" and the coulplings won't fit. I normally don't do this big stuff, but got the job through a friend. Any advise from you commercial and industrial guys would be greatly appreciated. Thanks a lot. Steve...

Work Gear for Electricians and the Trades
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204083
11/09/11 02:36 PM
11/09/11 02:36 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,050
Brick, NJ USA
A trip back to your hardware supply for sleeve anchors with 3/8 studs, as opposed to 3/8 hole diameter will solve this. You may also have to obtain the correct masonry bit for the anchors.

You also may consider mounting strut to the concrete, dropping rod down to another piece of strut, then you could use the anchors you have.





John
Re: Securing 3/8 rod to overhead concrete [Re: HotLine1] #204084
11/09/11 03:00 PM
11/09/11 03:00 PM
S
sparkync  Offline OP
Member
Joined: Oct 2002
Posts: 830
NC
John, that was my thought, but my electrical supply house didn't have any sleeves with 3/8 threads:( Kind of thought that was what they was supposed to be, "a supply house"
Thanks, I'll probably be looking at one of the other supply houses in the area.
PS. 3 electrical supply houses and none have a sleeve with 3/8" threads... I may have to go with 1/2" rod or something else. I must be doing something wrong:(

Last edited by sparkync; 11/09/11 03:03 PM.
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204085
11/09/11 05:44 PM
11/09/11 05:44 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,050
Brick, NJ USA
I used to get most of my hardware from WW Grainger or McmasterCarr. That was after the local hardware guys vanished as result of the big boxes.

The 1/2 & 1/2 combo may work, if ya can get your hands on the parts.



John
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204086
11/09/11 06:02 PM
11/09/11 06:02 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,322
Estero,Fl,usa
The big box will have a 3/8-18 Red Head.
(at least they do here). I am still not sure how good the "pull out" strength is.


Greg Fretwell
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204087
11/09/11 08:27 PM
11/09/11 08:27 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,050
Brick, NJ USA
Greg:

If I remember correctly, the sleeve anchors have a greater pull out than the 'red heads'. Sparkync might also see if there is a local Hilti store (or salesman) down his way.

I had a reference cd with all kinds of pull out & other data, but....darn if I can put my hands on it now.



John
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204088
11/09/11 09:08 PM
11/09/11 09:08 PM
T
Tesla  Offline
Member
Joined: Jun 2004
Posts: 1,273
Sacramento, CA
The typical Red Head powder driven pin can sustain 134 lbs per pin...

The typical 1/4" generic wedge anchor with 1.125" embedded can sustain 110 lbs per fastener...

So Red Heads are WAY under-strength for your situation.

Out my way anything as massive would require 3/8"-16 threads per inch...

If not 1/2" - !


Tesla
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204089
11/09/11 09:33 PM
11/09/11 09:33 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,050
Brick, NJ USA
Data from www.concretefastner.com

1/2" sleeve anchor (3/8 stud) 2000 PSI concrete....tension 2200 lbs (4:1 safety factor = 550 lbs each)

same in 4000 PSI concrete....4350 lbs (4:1 safety factor = 1087 lbs ea)

Spacing distances between the anchors factors into the precise engineering calcs also, but you should be OK with this.

BTW, the website above also sells anchors.



John
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204090
11/09/11 10:00 PM
11/09/11 10:00 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,322
Estero,Fl,usa
We must have a terminology thing here. To me a Red Head is a sleeve anchor, not a shot pin.

http://www.itwredhead.com/mechanical.php



Greg Fretwell
Re: Securing 3/8 rod to overhead concrete [Re: sparkync] #204091
11/09/11 10:36 PM
11/09/11 10:36 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,050
Brick, NJ USA
Greg:

Terminology issues for sure!

I hope when I said 'Hilti', that was not taken as a powder type anchor. They also sell mechanical anchors.



Last edited by HotLine1; 11/09/11 10:55 PM. Reason: Added comment re: Hilti

John
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