So I have seen People bolt Through the vibration isolation pads. In fact that was how I was taught to bolt down my transformers. Now it has been brought to my attention that that could potentially void the listing of the pads seeing how that requires drilling through the pad? I also feel like bolting trough will keep the pads from moving. This concerns me when they are mounted overhead. Any clarifications on this will be appreciated.
transformer Isolation pads ?
- Thread starter sparkyjr
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chris kennedy
Senior Member
- Location
- Miami Fla.
- Occupation
- 60 yr old tool twisting electrician
Never knew they had to be listed???
That's what I had thought I have never found a UL listing.
- Location
- Illinois
- Occupation
- retired electrician
The small ones inside the transformer have bolts though them. I don't see an issue as long as you are not compressing the pads with the bolts, but that also applies when you don't have bolts through the pads. However the pads are rated for "x" pounds per square inch and the hole would take some area out of the pad.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
Does the manufacturer have instructions on this?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
We use these (four waffles) for smaller transformers. I don't see an issue if you make a hole in the center of 4 of the waffles.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
I'm slightly confused--if these pads are for vibration isolation, then bolting the transformer through them defeats their purpose. The bolts can carry vibrations directly from the case of the transformer to the supporting structure underneath. Or if the bolts are to a fixed structure like a slab, then the bolts hold the transformer rigidly, resulting in greater air borne vibrations (noise).
There are vibration mounts made in which bolts are used as a backup only. The primary support path is through the rubber/isolation material only, and the support has some range of motion that way. The bolt acts as a limiter to extreme motion or in case the isolation material fails.
Cheers, Wayne
There are vibration mounts made in which bolts are used as a backup only. The primary support path is through the rubber/isolation material only, and the support has some range of motion that way. The bolt acts as a limiter to extreme motion or in case the isolation material fails.
Cheers, Wayne
- Occupation
- Licensed Electrician
I'm confused why anybody would be afraid to drill a hole in rubber pad.
You have to bold down the Xformer regardless so it doesn't walk from vibration. As long as you don't completely crush the pad it will still absorb a good amount of vibration and if it is hanging in the air as this one is its a must last thing I need is it falling in someone. =lawsuit
This is a job I have taken over they are already hanging I would have bolted through no matter what I'm just wondering if I should pull them down and move the pads. A lot of work for some thing that is already done if you get my drift. When I asked the other lead why he did it this way that was his answer he was told by another foreman he was wrong by bolting through and Told he had to fix it.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If the transformer is sitting on a pad, you can put a bolt next to the isolation pad and leave it loose in a loose hole, just there to keep the transformer from walking or from sliding in an earthquake or if hit by a truck.
That way the vibrating motion will be absorbed by the pad.One other hand, if you are hanging a transformer bolting to hold the weight, whether you also compress the pad or not, will transmit vibration through the bolt.
One way to avoid this is to have the upper end of the support bolt end attach to a backing plate which has a pad under it. Now the weight is resting on the isolation pad instead of a metal to metal connection through the bolt.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
I really think you are overthinking it. As long as you are bolting the transformer down you are going to have the bolt to transfer vibration, whether it goes through a hole in the pad or beside the pad. Just drill it (or leave it that way) and be done with it.
Why would you need isolation pads under a dry transformer anyway?
The core of the transformer is already on isolation pads. The factory bolts need to be loosened so they become effective.
I also wouldn't hesitate to drill through them if they are required for the project. They are redundant.
The core of the transformer is already on isolation pads. The factory bolts need to be loosened so they become effective.
I also wouldn't hesitate to drill through them if they are required for the project. They are redundant.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
- Status