Motor terminal box KO reduction

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greeny

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Hi guys,
I was wondering what method everyone uses to reduce the KO for a motor terminal box. For example, a standard 7.5 HP 3 phase motor may have a 1" KO, but is only wired with 1/2" flex. Do you use a threaded hub, hex reducing bushing or reducing tins? Or am I really supposed to order a custom peckerhead?
 
I may have just been "lucky" with my motor installs but often the thickness of the metal of the peckerhead didn't allow enough exposed threads on a fitting when I used re washers alone. I often ended up having to use nipples to get enough thread so often we would use a full size nipple with a coupling and bushing on top just to get a snug fit.
 
augie47 said:
I may have just been "lucky" with my motor installs but often the thickness of the metal of the peckerhead didn't allow enough exposed threads on a fitting when I used re washers alone.
Click to expand...
Have you tried flipping one of the washers over so it's the "wrong" way, or sandwiching more than one washer on each side?
 
I typically deal with dual voltage motors wired for 480. So I really dont want to use 1" flex for a few #14 wires, etc... I hate using reducing washers, especially when going down 2 sizes. They're just too flimsy and then the locknut loosens up eventually, not to mention it's just not a sturdy installation. And then playing that silly game Larry and Augie mentioned about flipping one over to get enough thread for the locknut. I figured there's a better method. Like using a hub to get a threaded entry.
 
is a threaded reducer long enough to get a locknut on each side of the hole? Then flex connector could screw into that...
 
greeny said:
Wireguru, I had thought of that. A hex-head threaded reducer would only require 1 locknnut...
Click to expand...

i had considered that, but thought vibration might cause it to loosen where the other kind of reducer (proper name escapes me at the moment) with a locknut on each side might be less prone to coming loose.
 
Coffeebean, I think you are correct.

Wireguru, there are not enough threads on a normal threaded reducer to work. I could barely get back-to-back locknuts on and that leaves no room for the thickness of the box.

Anyone? I need a better solution than reducing washers . . .
 
when I worked manufacturing industrial refrigeration units
the wielders would wield plates on them and
I would punch them to the right size.:cool:

I try to hub/re-bushing..but will use washers if thats what it takes.
 
Motor KO reduction

Motor KO reduction

You can always install a pullbox. Close nipple it to the motor j box.

I used the following: close nipple into motor j box ,threaded coupling into close nipple, threaded reducing bushing into coupling, flex connector into threaded bushing.

Joe
 
greeny said:
Coffeebean, I think you are correct.

Wireguru, there are not enough threads on a normal threaded reducer to work. I could barely get back-to-back locknuts on and that leaves no room for the thickness of the box.

Anyone? I need a better solution than reducing washers . . .
Click to expand...
I'll try again...Place a 1" coupling on top of the peckerhead (it normally will be adequately snug but put 1x1-1/4 RE washer under it if you like, from inside the peckerhead install a 1 X Close nipple or 1x**nipple (depending on the thickness of the peckerhead) with locknut and plastic bushing then install a RE bushing in your coupling to accept your feed conduit/flex.
Can't knock it off with a hammer.
 
augie47 said:
I'll try again...Place a 1" coupling on top of the peckerhead (it normally will be adequately snug but put 1x1-1/4 RE washer under it if you like, from inside the peckerhead install a 1 X Close nipple or 1x**nipple (depending on the thickness of the peckerhead) with locknut and plastic bushing then install a RE bushing in your coupling to accept your feed conduit/flex.
Can't knock it off with a hammer.
Click to expand...

I just can't help myself from thinking that's cheesy. Sorry . . .

I like the welded plate. The hub with the reducing bushing seems best. Why can't the manufacturer's give us the smaller KO and let people enlarge the KO if necessary? I mean, most 20 HP motors are probably used at 460, not 230.
 
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