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Topic Title: PCB Mains Line E to L/N Spacing when potted?
Topic Summary: Does potting a PCB (100% encapsulation) change the minimium line spacing?
Created On: 15 February 2013 09:34 AM
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 15 February 2013 09:34 AM
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jonrossmorgan

Posts: 2
Joined: 19 June 2003

I am starting to layout my 1st mains (90-260VAC 1Ph) PCB that will be fully encapsulated within epoxy potting compound (PX804C Flame Retardant 18kV/mm), and obviously this is a Class 1 device. Space will be limited, so I was wondering if the epoxy insulation will allow me to reduce the 8mm E-L/E-N Spacing? There is an exposed 'Earthed' Heat sink that will protrude through the epoxy, and low voltage terminals <32VDC. I do not have a issue with the mains to DC spacing, just the L/N/E spacing. Logic would tell me that the potting would act as a very good basic insulation, with little creepage possibility, so a much smaller spacing would be allowable. I cant specifically find this situation referenced, any advice would be greatly appreciated. Kind regards Jon

Edited: 15 February 2013 at 10:12 AM by jonrossmorgan
 15 February 2013 04:11 PM
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cblackha

Posts: 76
Joined: 21 January 2003

>8mm E-L/E-N Spacing

That's high - which standard are you using / what directives do you need to comply with?

Charlie
 18 February 2013 09:44 AM
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jonrossmorgan

Posts: 2
Joined: 19 June 2003

I used to work in Military with high pollution levels, but now I'm in commercial I suppose that level of isolation is not required.
I haven't got a copy of any regulations here, what standards should I be looking at for a normal commercial/domestic CE marked product?
( EN60065?)
As far as I can tell EN60065 requires 3mm spacing on class I, is this good enough? Bearing in mind there is no pollution and high dielectric insulation (potting)
 19 February 2013 07:49 PM
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cblackha

Posts: 76
Joined: 21 January 2003

Pick the most appropriate Harmonised Standard for your product from http://ec.europa.eu/enterprise...-voltage/index_en.htm

60065 would be correct standard for AV and similar equipment, alternatively 60950-1 could apply.

Cheapest, reputable, place for standards is Estonian Standards Centre: http://www.evs.ee/Esileht/tabi...ge/en-US/Default.aspx

I don't have a copy of 60065, and there are normally a few things that feed into the creepage/clearance requirements, but 3mm is in the right ball park.
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