The big transformer question.............

[silversaddle1]

We will always cut the copper coils out of the larger transformers (anything over 80 pounds as a rule) and just sell the smaller ones as whole units. I have always wondered about the difference in value whole vs. stripped. So today I am caught up on my work in the shop, and after just scrapping some telecom racks, I have this 65 pound transformer sitting on the bench. What the hell, today I find out.

So with the three most basic tools of the scrapman's trade (sawzall, hammer, and big screwdriver) I begin to strip out the transformer. What I discovered suprised even me.

If I would have just tossed the transformer in with the others I would have got paid .40 cents a pound. So .40 x 65 pounds = $26.00. Not bad, but read on.

By stripping the transformer, here is what I ended up with.

42 pounds steel core x .13 cents a pound $5.46
5.5 pounds #2 copper (secondary coil) x $3.80 per pound $20.90
16.5 pounds #1 copper (primary coil) x $4.05 per pound $66.82
TOTAL $93.18

So if you subtract the two totals, I see I made $67.18 for about 40 minutes work!

Not too bad!

 

[Anonymous]

In most cases you will make more by stripping them......however don't forget that the copper content is contingent on the voltage,amperage,and resistance of the transformer.
I don't think I have ever seen one where I did not make a good profit by stripping it,but I have stripped some where it is hard to justify the time and labor,for the profit.

 

[Reno Chris]

Right - you guys do know that commercial transformers built before 1980 commonly contain PCB laced transformer oils. PCBs are a really nasty hazardous chemical (Polychlorinated Biphenols). Cancer causing nasty stuff, and the fine for improper disposal of PCBs would be maybe 500 to 1,000 times what you'd get from the copper scrap - heck in many places you could probably do jail time for PCB disposal into the normal household trash stream.

I'm not trying to pick a fight or anything, just pointing out a very serious issue with commercial transformer disposal and recycling. Many operators would gladly have you haul away their PCB contaminated transformers - because proper disposal of the PCBs cost far more than even a $100 scrap payment.

Hopefully your transformer is much newer.

 

[Harold_V]

Right - you guys do know that commercial transformers built before 1980 commonly contain PCB laced transformer oils. PCBs are a really nasty hazardous chemical (Polychlorinated Biphenols). Cancer causing nasty stuff, and the fine for improper disposal of PCBs would be maybe 500 to 1,000 times what you'd get from the copper scrap - heck in many places you could probably do jail time for PCB disposal into the normal household trash stream.

I'm not trying to pick a fight or anything, just pointing out a very serious issue with commercial transformer disposal and recycling. Many operators would gladly have you haul away their PCB contaminated transformers - because proper disposal of the PCBs cost far more than even a $100 scrap payment.

Hopefully your transformer is much newer.

Readers will be well served to pay attention to your admonition.

I have been personally involved in the (legal) disposal of PCB's on two occasions. Trust me---it's complicated and expensive. Here's an accounting of the first encounter:
I was given two induction furnace power supplies several years ago. The were early technology, transformers with capacitors and mercury spark gaps to develop the required frequency. The donor played up the mercury, as if it was the only problem, and had me sign a waiver limiting his responsibility. A letter to Ajax Magnethermic quickly revealed the fact that both of them contained PCB's, and, fortunately for me, the fact that each of them had minor leakage made transfer of title illegal (according to federal regulations). I contacted the donor (out of my state) and informed him that I had no alternative but to dispose of them legally, which I would manage, but he was to pick up the tab. Otherwise, EPA would get involved (I had already discussed the issue with them and had withheld his name in an attempt to eliminate any legal entanglements). He agreed, and paid the tab. Cost for disposal was slightly over $3,000, and that with me providing all of the ground work at no charge. The oil was sent to a licensed incinerator, but the solids were sent to a landfill in Coffeyville, Kansas, where they are buried with an address. Should they ever require attention, they are registered in the name of the donor, who would be responsible for all expenses.

Do avoid oil filled transformers, in particular if they were made from the 30's forward, until most likely the late 70's. Not sure of the later date, just use good sense. It might pay to note that PCB's were looked upon as a miracle dielectric, so it's entirely possible even earlier transformers may have had the oil replaced with a PCB, which was made under various trade names.

Harold

 

[silversaddle1]

Thanks for the heads up. I should have stated that these are air cooled dry wound transformers.

 

[adam_mizer]

Sounds like you did well.
But I have a question.
Both primary and secondary are or should be number 2 copper. I mean didn't they both have a type of insulating varnish, formvar, polyamide, or one of the many others?

 

[skippy]

Heh, I wonder what % of PCB potted fluoro ballasts are properly disposed of....

 

[silversaddle1]

The primary coil is a lot thicker than the secondary coil. Yes, it has a coating of varnish on it right now, but a while in the burn barrel with some scrap wood will burn the varnish right off, with little or no smoke. And I have a lot of scrap wood around here. :lol:

 

[escrap]

Scott,

Thanks for the break down. We currently have a 250 pounder in our transformer box, I would sure love to break it down and see what I have, only trouble digging through the box to get to the bottom. Decisions decisions. lol

 

[silversaddle1]

Scott,

Thanks for the break down. We currently have a 250 pounder in our transformer box, I would sure love to break it down and see what I have, only trouble digging through the box to get to the bottom. Decisions decisions. lol

Zack,

I know, right?!! That's just it, a guy can do pretty good stripping them, but the time involved is the sticker. A 250 pounder would be stripped for sure around here.