HELP! Re-torqueing Connections

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Please help! i thought I remember reading somewhere on here it was advised AGAINST REtorqueing of connections on breakers for maintanance for risk of doing more damage. But after reading the 'Standards and practices of proper maintainace,' (I may be off on the title ) it says it MUST be retorqued. Does anyone have any other info on this?? Thanks.
 
I have been on several preventative maintenance jobs where I have had to re-torque the gear. If there is information against this practice, I would be interested in reading it.
 
ANSI and IEEE agree on this, breaker connections should be either, retorqued, IR scanned under load, or tested with a microhmeter. The markings on the bolts tell you the values they should be torqued to. We usuallly do the microhmeter method during switchgear maintenence, and we torque and record values for equipment we ship.

The thread you are refering to was talking about screws in terminal blocks, those types of "connections", which should not be "retorqued" (I use that term loosely because most electricians dont use any calibrated torquing tools when they use this term, they just tighten the screws down with a screwdriver), but rather should have thier compression washers checked or IR scanned under load.
 
Interesting because there has been info posted here that there is no way to 're-torque' a wire termination short of removing the conductor, cutting it off, re-stripping it and then put it back into the termination and finally bring it to torque.

It has been said that to keep re-torquing wire terminations causes cold flow and the eventual destruction of the conductor due to crushing.

I am not pretending to know the answer here, I am only pointing out there have been good arguments on both sides of this issue.
 
What do you mean by re-torquing?

A) Breaking the connection open then starting from scratch, retighten it to the specified torque rating.

Or

B) Putting a torque wrench on a previously torqued connection and pulling on the wrench until the torque reading is reached.
 
jim dungar said:
What do you mean by re-torquing?

A) Breaking the connection open then starting from scratch, retighten it to the specified torque rating.

Or

B) Putting a torque wrench on a previously torqued connection and pulling on the wrench until the torque reading is reached.
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I would say B. I've seen this done as preventive maintenance without any problems.
 
infinity said:
I would say B. I've seen this done as preventive maintenance without any problems.
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In my opinion B is absolutely wrong.
Almost every cable connection I have seen that has been regularly retorqued in this manner has eventually failed. Granted it took some devices 15yrs before they failed.

I have never seen a set of testing instructions that recommends this practice.
 
jim dungar said:
In my opinion B is absolutely wrong.
Almost every cable connection I have seen that has been regularly retorqued in this manner has eventually failed. Granted it took some devices 15yrs before they failed.

I have never seen a set of testing instructions that recommends this practice.
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Well I guess that it depends on who you ask and when the re-torquing became taboo. 15 years ago this was SOP for a huge data center that I worked in. Yearly maintenance did just that, re-torqued every CB, neutral and feeder. Never heard of a problem and it was an accepted practice at the time. Maybe those connections are beginning to fail right about now. :rolleyes:
 
chris kennedy said:
The instructions that come with torque wrenches would suggest you break the connection loose before retorquing.
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Actually it depends on the type of connection and the manufactures recommendations

Some have a re-torque values that are less than the original torque specifications.

If a connection was over tightened upon original installation, re-torque does nothing other prove it is not lose and this should IMO be caught on an IR inspection.

During an EPM it is not practical to losen and retighten connections.
 
Rob I used to do that as well, for example once a year we would shut down Sunmicros campus and re-torque all the large equipment. We made good money doing it and Sunmicro thought it was the right thing. Now I am wondering if it really was the right thing.

It makes sense to me that if I get a 1/4" turn out of the connection every year that something is deforming and that is likely the conductor getting flatter and flatter.
 
jim dungar said:
I have never seen a set of testing instructions that recommends this practice.
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ANSI/NETA have this in many sections of both the ATS and MTS testing procedures.

7.Inspect bolted electrical connections for high resistance using one of the following methods:
1.Use of low-resistance ohmmeter in accordance with Section 7.1.2.3.
2.Verify tightness of accessible bolted electrical connections by calibrated torque- wrench method in accordance with manufacturer?s published data
or Table 100.12.
3.Perform thermographic survey in accordance with Section 9.
 
zog said:
2.Verify tightness of accessible bolted electrical connections by calibrated torque- wrench method in accordance with manufacturer?s published data
or Table 100.12.
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I have not seen the manufacturer's data that says to keep tightening the connection.

I have seen brass connectors and aluminum lug bodies that deformed and split after continuous tightening.
 
Jim,
I think you and Zog are talking about different types of connections. I think he is talking about things like bus bars or a wire terminal connection to the bus bar or breaker. I believe you are talking about a mechanical wire termination where the screw you are re-torquing applies direct or indirect pressure to the conductor itself. It is my understanding that the second type of connection should never be re-torqued.
 
The focus seems to be the affect of re-torquing on the material being fastened.

Let's not ignore the adverse effect on the fastener itself. For example, head bolts on a racing engine are never retorqued, not because of clearance with the head or gasket, but because the fastener deformation is calculated into the torque value. Further retorquing goes out of the engineered range of the fastener.
 
jim dungar said:
I have not seen the manufacturer's data that says to keep tightening the connection.

I have seen brass connectors and aluminum lug bodies that deformed and split after continuous tightening.
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Which is why some connections have a re-torque value that is less than the original value.

But in theory I would think that as long as you stop at the prescribed value utilizing a calibrated torque wrench your connection is still better than 99% of the connections that are grab on and pull till you sweat tightened.
 
don_resqcapt19 said:
Jim,
I think you and Zog are talking about different types of connections. I think he is talking about things like bus bars or a wire terminal connection to the bus bar or breaker. I believe you are talking about a mechanical wire termination where the screw you are re-torquing applies direct or indirect pressure to the conductor itself. It is my understanding that the second type of connection should never be re-torqued.
Click to expand...

Exactly, that is what I posted before and am trying to explain now.
 
jim dungar said:
What do you mean by re-torquing?

A) Breaking the connection open then starting from scratch, retighten it to the specified torque rating.

Or

B) Putting a torque wrench on a previously torqued connection and pulling on the wrench until the torque reading is reached.
Click to expand...


I believe B) is the more appropiate one. Ive been doing some maintainance and this concerns 'RE torque' main breakers (800, 1200 am0 etc) . Also the buss bar connections of the some of this 500 mcm wire using allen wrenches. This is old gear, some as old as 25 years.

I then recall someone saying that to retorque to the original spec on these connections is not the best thing to do. I have yet to read that 'officially' somewhere. I have the 'standards for maintainance' book and it says to RETORQUE. So I suppose we will continue to follow this practice.
 
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