480 Volt UL pc board creepage distance requirement?

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#1
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Hello all you experts out there!

I'm prototyping a pc board for an Avr driven 480 volt phase control.
Would anyone happen to know the pc board creepage distance required
by UL for that voltage?

Thanks!

Tom Pappano
Tulsa, Oklahoma

Tom Pappano
Tulsa, Oklahoma

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UL508 "Industrial Control Equipment" may apply. From table 34.1, the creepage distance would be 12.7mm (0.5"). However, having said that, you should really read the standard yourself. There are exceptions and other requirements that may or may not be relevant to you. And if you're going for approval, fixing mistakes after the product is done is very expensive.

Arthur

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That helps, I know adding things like conformal coatings can reduce clearances
but I'm just trying a "worst case" sample layout to see how it looks before buying
some more UL $tandards.

Thanks for the info,
Tom Pappano
Tulsa, Oklahoma

Tom Pappano
Tulsa, Oklahoma

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240V requirement ( in australia) is 6 mm creepage gap from memory.

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UL508 doesn't directly give creepage and clearance distances for conformal coated boards, it refers to another standard for that (which I don't have). What does make a big difference is when your circuit has transient suppression devices in it. You may have them already to protect the power semiconductors. For example, in a circuit with short-circuit power of <10kVA and a transient voltages limited to 900V, you can go down to 5.08mm (0.2").

Arthur

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Hi,

adding an air gap - if possible - can decrease the distance.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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KLAUS,

yes .. routing a slot provides improved characteristics

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Thanks for the responses, guys! I will lay out my sample board with 6mm and see
how it looks. That may be a useable distance, we will see when I get some more
standards info. Slots are a possibility, but first choice is to keep the pcb cheap
as possible to fabricate.

Thanks,
Tom Pappano
Tulsa, Oklahoma

Tom Pappano
Tulsa, Oklahoma