Foot pounds of Torque for breakers and lugs.

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busman said:
... The largest torque I remember using was 300 in-lb which is 25 ft-lbs. Most wrenches marked in ft-lbs will not measure that low.
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Hmmm... haven't torqued any busbars with large bolts lately, huh?

Just torqued up some last week. The [Italian] engineers provided torque specs in N-m, but were kind enough to also convert to in-lbs. Unfortunately, our torque wrench was calibrated in ft-lbs :roll: As I recall, when converted the torque spec'd for largest bolt size used (M16, I think) was over 100 ft-lbs. :confused:

Additionally, the lowest torque setting on our wrench is 15 ft-lbs.
 
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Smart $ said:
As I recall, when converted the torque spec'd for largest bolt size used (M16, I think) was over 100 ft-lbs. :confused:
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Since you said this was overseas stuff, did it not use Bellville washers, maybe? I notice the torque spec often does seem higher on bus connections without Belleville washers or Belleville-type nuts.

My present gripe is with the bus connections in Milbank ganged meter sockets. They strip out about 2 pounds beyond the torque spec. No nuts on the back side. The two overlapping sections of bus have the front piece with a clearance hole and the back piece with a tapped hole, and it's all aluminium.
 
mdshunk said:
Since you said this was overseas stuff, did it not use Bellville washers, maybe? I notice the torque spec often does seem higher on bus connections without Belleville washers or Belleville-type nuts.
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That is correct. No belleville washers or nuts.
 
mdshunk said:
My present gripe is with the bus connections in Milbank ganged meter sockets. They strip out about 2 pounds beyond the torque spec. No nuts on the back side. The two overlapping sections of bus have the front piece with a clearance hole and the back piece with a tapped hole, and it's all aluminium.
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I'd gripe, too.

Would it be a violation to put jam nuts on the backside?
 
Smart $ said:
Would it be a violation to put jam nuts on the backside?
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Beats me, but that's how I fix 'em. The bolt is long enough.

I might have exaggerated when I said 2 pounds. It might be as high as 3 pounds.
 
stuartdmc said:
I ran a 225amp feed 400ft with (2) 2?conduits - 4 #2/0 THHN copper each, to a 225 amp dock powered pedestal. To prevent an extreme voltage drop I up sized my wire and ran parallel runs. The problem is that I have installed my OCPD in line prier of going down to the dock , and now, I am finding out that the 225A circuit breaker within the Disconnect will not accept two 2/0 wires or double lugs. So, what I?ve done is, I?ve cut in a junction box to tap and extend each conductor, both line and load with a single 4/0 wire going too and from the circuit breaker. This connection is made using a ?Greave? connector rated for 250kcmil to a # 6 AWG.
This is what the inspector needs to see the torque on as well as the circuit breaker,

Oh, the main 225A circuit breaker won?t accept the two wire?s as well.
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It was at that point that I realized that I didnt want a pickle I just wanna ride my motorcycle. ONLY THE OLDER GUYS will remember this one. Arlo Guthrie
 
quogueelectric said:
It was at that point that I realized that I didnt want a pickle I just wanna ride my motorcycle. ONLY THE OLDER GUYS will remember this one. Arlo Guthrie
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There was only one thing that Ray could say, "And I don't want to die.....just want to ride my motorcy.........cle." :cool:
 
mdshunk said:
Since you said this was overseas stuff, did it not use Bellville washers, maybe? I notice the torque spec often does seem higher on bus connections without Belleville washers or Belleville-type nuts.

My present gripe is with the bus connections in Milbank ganged meter sockets. They strip out about 2 pounds beyond the torque spec. No nuts on the back side. The two overlapping sections of bus have the front piece with a clearance hole and the back piece with a tapped hole, and it's all aluminium.
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Belleville washers are concave spring steel, aren't designed to be fully colasped, wouldn't provide full area contact and wouldn't provide a solid connection. Belleville nuts? Sure you don't mean a skirted nut, a nut with a built in washer?
 
locnuts_bwn.jpg


Belleville Washer Nut

Large flange distributes torque load and restricts compression of material.

Spring steel washer maintains surface contact as material expands and contracts.

Prevailing torque remains high even when connection is subject to vibration.​


From here
 
iwire said:
locnuts_bwn.jpg


Belleville Washer Nut

Large flange distributes torque load and restricts compression of material.

Spring steel washer maintains surface contact as material expands and contracts.

Prevailing torque remains high even when connection is subject to vibration.​


From here
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I didn't think that you'd want a springy connection but, heck, I'm not a electrician! In that case, torque specs would be very important.

If that type of nut wasn't used, I'm sure torque specs would be much higher.
 
wptski said:
I didn't think that you'd want a springy connection but, heck, I'm not a electrician!
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'Springy' hardware is commonly used for bolted electrical connections. The spring is intended to maintain the same clamping force regardless of the expansion and contraction of the material. :smile:
 
iwire said:
'Springy' hardware is commonly used for bolted electrical connections. The spring is intended to maintain the same clamping force regardless of the expansion and contraction of the material. :smile:
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Have seen spring washers 2"-3" in diameter used in a huge stack! Talk about clamping force.:rolleyes:
 
wptski said:
Belleville washers are concave spring steel, aren't designed to be fully colasped, wouldn't provide full area contact and wouldn't provide a solid connection.
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I disagree, mainly because there was a period of time when ITE switchgear came with alternate torque instructions to tighten the bolts until the Belleville washer flattened, then back off 1/4th turn (the washer was still pretty much flat when you backed off). The Belleville washer isn't the contact area anyhow. The bus-to-bus contact area is what matters. The Belleville washer just keeps tension on the connection through heating and cooling cycles.
 
mdshunk said:
I disagree, mainly because there was a period of time when ITE switchgear came with alternate torque instructions to tighten the bolts until the Belleville washer flattened, then back off 1/4th turn (the washer was still pretty much flat when you backed off). The Belleville washer isn't the contact area anyhow. The bus-to-bus contact area is what matters. The Belleville washer just keeps tension on the connection through heating and cooling cycles.
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You were adusting the Belleville washer to be within it's spring range then. If it was a seperate piece, they could have you rotate it till washer made contact and so much of a turn tighter after that.

It's like adjusting hydraulic lifters on a gas engine, with it running hot, you loosen till they start clacking or zero lash and tighten so many turns down to what the specs were.
 
wptski said:
It's like adjusting hydraulic lifters on a gas engine, with it running hot, you loosen till they start clacking or zero lash and tighten so many turns down to what the specs were.
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I'll have to take your word on that. :) All I know about engines is that they're under the hood.
 
I own a variety of torque wrenches, Snap-On 1/4", 3/8' and can be order in FT/lbs or Inch/lbs, the 1/2" are all ft/lbs. Then one of my diesel mechanics has one 48" long, by Snap On when I asked him what that puppy cost me he just smiles.
 
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