Liability in amp building

[tjauernig]

I do UL calculations/studies all the time at my day job with Siemens. Fault current is the biggest conscern.

UL looks at the amp as a load consisting of power and control. Everything after the power transformer is control, and not subject to a fault current rating. Put a properly rated Ground fault interrupt module on your power supply, and the amp will be shut down if there's trouble.

ALSO - big one here! If you're gonna sell, two things:

1. Get an LLC

2. Put a label in the amp, that states. NO user servicable parts inside.

CE is a whole different issue, that goes a lot more in detail than UL.

There's also quite a few "boutique" brands that do not bear the UL mark.

UL is a finicky organization, and I agree with some of the previous comments about testing methods. Some of their testing criteria are situations where electricity just doesn't work that way.

And, UL or not, if you're amp kills somebody, don't for one minute think a UL sticker will keep you from getting sued.

Then there is the cost of the whole UL thing. Only the big boys (Fender , Boogie, etc) can afford the sticker.

I could type for days on this UL stuff.....I've lost track of how many arguments I've had with UL in the last 10 years.

Also, one more tip, if at all possible, buy UL "listed", NOT "registered" parts when you can. But, in the amp building world, they are tough to find.

[CathodeBiased]

:I saw on another posting where a guy said he quit building amps for fear of being sued.

Product liability was one of the big reasons why tube technology was put out to pasture. Solid-state technology has the advantage of having no user serviceable parts and lower operating voltages (i.e., solid-state devices are less likely to "arc").

[tjauernig]

Lower voltages is the reason a lot of EU countries use DC stuff in ther industrial world. Less liability and such. But, even then most countries only allow a "qualified" tech into the machine control panels. Some sites I've been on (ie. Isreal, Ireland, England) won't even allow the engineer that designs/builds the panel to go inside it once it lands on site.

Fact is reliability has nothing to do with solid state vs. tubes at all. A well designed product of either type will withstand use well. Cost was the basis for the switch. Small parts, mounted on circuit boards, built by automated machines.

You still have a power supply to convert AC to DC, and the amp still runs DC. Very different voltages, but when it comes to current, and how little it takes to stop your heart, the liability is the same. And in the case of DC, the arc can actually be greater than with AC depending on the situation and the products/application used.

If you studied UL codes, you'd realize they are written to defend which ever side of the argument they (UL) feels like supporting. I can't tell you how many times the local inspector has said to me, "well, it's all subject to interpretation of the inspector involved". I've thrown a few inspectors off the site for that remark. It's write or it's wrong period. I've also had panels pass an inspection, only to build another one just like it a week later, and the same inspector fails it. Talk about a kick in the yams!

UL is a pain in the ass, that's one thing that is for sure. The other is that anyone can sue you for anything in the world today.