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Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
This is going to be interesting; for once the shoe is on the other foot!

Folks here know me from my previous work and contracting experience. These days, I'm on the payroll of a fairly serious industrial operation. I've been made "Lord of the Fans."

Well, I have a fan that doesn't work. By all appearances, the problem is likely to be found in the junction box just under the rooftop fan, inside the building.

Mind you, this is the highest roof within 60 miles. The fan has a cap about 6-ft. square and blades about 3-ft. in diameter. A bit more than can be readily manhandled.

Just as bad, they built the plant under this fan, and there is NO accessibility- unless you have a jet-pac.

I did propose an approach, only to be told 'we'll bring in a contractor.' It will be interesting to see how HE does it. Or, perhaps, the 2-yr. old fan will simply be abandoned.

It's also interesting that the safety department has forbidden getting to the fan using the very means used by the original contractor.

Last edited by renosteinke; 09/24/13 07:09 PM.
Joined: Sep 2013
Posts: 43
Member
Are you able to provide a temporary voltage of similar demand to temp up the questioned fan from any available rooftop connection vantage point to confirm if the problem is in fact the fan itself rather than the supply voltage below ..


Anyone claiming to know everything about Electrical, is wrong.
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
That can be done - hasn't been tried, but can be done.

What I really want is a TDR to confirm my suspicions about the location of the problem. Junction boxes are always on the short list of suspects - though cable makers have been known to make poor splices in their products.

Making a wild guess ... if the run is 500 ft, all but small sections (totaling maybe 10 ft.) is visible, run in the open, on cable tray. The only junction anywhere is in the box right under the fan.

I've got power leaving the starter, but not making it to the fan. It's that simple. Makes me wonder if the fan ever really did work.

FWIW, the cable / starter / fan IS identified incorrectly. This makes me speculate that the installer knew there was an issue somewhere.

22 fans on this part of the complex, and I have issues with 5. At least 4 are marked incorrectly. None have been greased, ever. One had the belt sheaves wildly out of line (loose set screw). I'm not impressed by the various contractors they've had "maintaining" these fans.

Joined: Sep 2013
Posts: 43
Member
Before I slap a jet pack on I'd simulate a good known voltage right at the fan .. at least you won't waste your time or endanger yourself unnecessarily, I've trouble shot other loads in a similar manner .. it's so cool when you can isolate a system on what the problems are not .. good luck reno ..

Last edited by MarkC10; 09/25/13 07:51 PM.

Anyone claiming to know everything about Electrical, is wrong.
Joined: Jul 2004
Posts: 9,673
Likes: 7
G
Member
How high up is this? Man lift range or "hook and ladder truck"?


Greg Fretwell
Joined: Apr 2002
Posts: 7,283
Likes: 3
Member
Reno:

This intriges me:
"It's also interesting that the safety department has forbidden getting to the fan using the very means used by the original contractor."

Could this 'means' be taking the big cover off from the roof to access the fan??

I had something similar back in the day. Vacant bldg, 45' slab to deck; unmarked panels; we dumped the main and did an attack from the rooftop.



John
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
Actual height to ground isn't anything exceptional. The issue is that other stuff, such as production equipment, gets in the way. Then, supposing you get up there, the depth of the trusses puts the box out of reach of someone in a basket.

Even if you let a trained monkey scale the cable tray, the final run is off to the side, so you could not reach the box, or see inside.

I see no point in worrying about the fan itself, when we KNOW power isn't getting to it.

The original contractor put a 20-ft. little "Genie" 1-man lift atop one of the overhead cranes.

The fan assembly easily weighs 300 lbs, with nearly half of that for the motor alone. I proposed taking the fan apart and constructing a platform to hang either off the curb, or the trusses below.

I also proposed making a sled to transport equipment - like replacement motors- across the sheet metal roof. No dice, I was told- "Engineering" says we can't do that, because it's "not a structural roof deck." Yet, somehow, it's OK with engineering for me to put that 140# motor on my shoulder and walk across the deck!


Joined: Jul 2004
Posts: 9,673
Likes: 7
G
Member
I suppose I could come up with something using the cranes but I am sure they are not "man rated" so it would be illegal.

Maybe have them build a catwalk off the trusses.
This is not going to be the last time this comes up

I suspect you could get a truck crane to get equipment up on the roof.


Greg Fretwell
Joined: Apr 2002
Posts: 7,283
Likes: 3
Member
Reno:
Have you or anyone considered any rental equipment?

This is one of many; depending on your area.

http://www.jlg.com/en-US/Model.html...uId=d39badf6-70c2-4fa3-a03c-268cb1f085d7


John
Joined: Sep 2013
Posts: 43
Member
I don't know why the designers did not consider the connection point at the roof, Isn't there a disconnect .. It obviously didn't get inspected because no inspector would allow a splice point that was not readily accessible.

Chances are a poor connection finally arced apart from the excessive load upon a poor connection, finally oxidizing to the point of an open.

I'd sell them on keeping all the fan circuits up on the roof using strut and either simple EMT or better yet rigid..

Careful on that poor design, it sounds dangerous either way.

Maybe get a crane, pull the unit, get the slice point on the roof and start from there.

Good luck, it sounds like a major hassle. But a nice challenge ..


Anyone claiming to know everything about Electrical, is wrong.
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