DSH 627 Clearance, creepages distances and solid insulation

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DSH 627 8 r6 w+ A2 g& _ 2 Z0 {- P9 D! w# l6 `

Clearance, creepages distances and solid insulation

21.2 and 29.3 ) S$ Z6 d  g" V0 r) p- [

60335-1(ed.4) & p& N# E: x5 B  e

2 Z$ @( B. @3 P8 F) x/ D; XQuestion:
Sub-clause 29.3 states the requirements for the thickness of solid insulation do not apply to inaccessible insulation providing the other requirements stated within the sub-clause are met.
The question is about a product where a thin insulation sheet used within the product met the requirements of the standard for inaccessible insulation once the product had been installed. However, during installation the inaccessible insulation is accessible and, although electrically the insulation meets the requirements, mechanically we found it could be easily damaged.
The product is an instantaneous water heater that is permanently plumped into the water supply and electrically connected to fixed wiring. A professional competent person normally installs the product.
4 H: X3 X4 v0 Y& O" z/ PThe question is if this insulation is adequate even if it can easily be accidentally damaged but meets the requirements of the standard if it is not considered an accessible part.
! K5 D! ]2 k( s3 E7 q. HDecision:
% ~4 }$ ~' _, |, rTaking into account the definition of accessible part (3.6.3) and the test of 21.2, if there is a risk of insulation damage, the scratch test shall be performed on the insulation which is accessible during installation. When verifying if it can be easily damage, instruction given as required by sub-clause 7.12.1 is also taken into account.

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