Silicone Bronze Hardware

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A-1Sparky

Senior Member
Location
Vermont
I'm wondering if I should be using silicone bronze hardware (nuts, bolts, washers) for mechanical lug mounting in transformers/switch gear or is standard grade 8 steel acceptable? I've seen tons of installs with standard hardware with seemingly no ill-effects. Is the extra money worth it? Thanks in advance.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
The bolt is just there to hold the lug to the tongue or bus bar. the current mostly flows directly between the lug and the tongue or bus bar.

As long as the materials are compatible, there is no need to buy expensive bronze hardware.

Must lugs I see these days and most tongues are tin plated, so std zinc plated steel should be fine.
 
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A-1Sparky

Senior Member
Location
Vermont
Thanks for the replies, guys. So, when, if ever, would you use silicone bronze hardware? I recently had to check a transformer's mounting hardware for the proper torque, and read that the hardware was all silicone bronze. It got me thinking that maybe it was a better choice as far as conductivity goes.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Thanks for the replies, guys. So, when, if ever, would you use silicone bronze hardware? I recently had to check a transformer's mounting hardware for the proper torque, and read that the hardware was all silicone bronze. It got me thinking that maybe it was a better choice as far as conductivity goes.

I would use them in a couple of places.

1. Where there was a material compatability issue.
2. Where the bolt, nut, or washer was a significant part of the actual electrical connection and not just there to hold the electrical connection in place.

On one occassion, I had to have our shop stack lugs that did not stack real well. A bronze washer between the two lugs as a spacer fixed the problem. In that case, there was actual electricity flowing through the washer so it made sense to me to make it as conductive as possible.

normally there is not all that much current flow through the hardware.
 

A-1Sparky

Senior Member
Location
Vermont
I would use them in a couple of places.

1. Where there was a material compatability issue.
2. Where the bolt, nut, or washer was a significant part of the actual electrical connection and not just there to hold the electrical connection in place.

On one occassion, I had to have our shop stack lugs that did not stack real well. A bronze washer between the two lugs as a spacer fixed the problem. In that case, there was actual electricity flowing through the washer so it made sense to me to make it as conductive as possible.

normally there is not all that much current flow through the hardware.


It makes sense that there normally wouldn't be that much current flowing through the hardware...I just had to consider it a little more. Thank you for the insightful reply.
 

SG-1

Senior Member
Follow the instructions supplied by the equipment supplier. We call for grade 5 or better hardware. 25 years ago I used to see a good bit of silicone bronze ( everdure ) hardware, but not anymore. I cannot recall seeing any for many long years. If my memory is correct it was used in orders that also required tropilization.

Besides providing the clamping force for the joint, it needs to be able to survive the mechanical forces of a fault. There may be seismic requirements to meet as well.
 
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