My LM3886 HIFI AMP!!!

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The usual recommendation is to have 1 mm separation per 100 V between adjacent non-isolated leads. For 230 V you should use 100 mil (2,54 mm) or more separation. It makes no difference, whether you route a slit into the PCB or not, because the isolator remains to be air.
mains is just not any voltage. Maybe I'm getting old, but don't call VDE and EN standards for 6mm creapage distance? :confused:
 
thank you both!
I had a short glance into the standard yesterday and have an idea now, where my previous rule of thumb may came from.
In short:
There are creepage and spark distances. The creepage distance is not allowed to be lower than the spark distance. While creepage is calculated on the nominal voltage, spark distance has to be determined on line transients which are different for different equipment categories.

have fun!
 
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Again for creepage and clearance refer to the relevent spec, for Europe mains the spacing is 4mm clearance and 8mm creepage, this is between any copper feature. There are no rules of thumb and 1mm per 100V is wrong. This is as important as having a safety Earth, as you are putting people at risk of electrocution if you dont follow the rules.
You can decrease the creepage requirement if you use a slot of 1mm or over betqween the conductive parts, but you cannot reduce the cleanence distance as a hobbyist. This is why when mains is present on commectial equipement, quite often they will use 10mm spaced connectors to g 8mm between ther pads.
Use 3mm with european mains and you are breaking the regs, and will be liable if any problems occur. European mains is not 230 but 253 for these calculations.
 
maybe I should have given post #46 a sharper edge:
Calculating isolation distances according EN 60664 is nowhere that simple as "1mm per 100V".
I won't give you any numbers.
Any manufacturer has to understand and do the calculations on his own.

The humble amateur instead should have a sharp look at european or japanese brand equipment and see how those deal with mains voltage.
 
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Again for creepage and clearance refer to the relevent spec, for Europe mains the spacing is 4mm clearance and 8mm creepage, this is between any copper feature. There are no rules of thumb and 1mm per 100V is wrong.

The relevant spec is EN 60664-1. Table F.1 in the following link shows the relevant distances. Equipment for home audio can be considered pollution degree 2. Material group III is the worst case and from 150 V to 1000 V it shows 1 mm creepage per 100 V.

European mains is not 230 but 253 for these calculations.

Treat it as if it was 300 V and make the air gap 3 mm to get a healthy safety margin.
 
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