> Aha! Now I understand why EN60950 only tells us about the OD of the > conduit: because that's the same as the OD of that part of the > conduit hub that mates with your enclosure! If (big IF) the methods > explained below for the UK also apply everywhere else in Europe, then > I have part of my answer. We would simply make the knockout slightly > larger than the OD of the conduit. > > There is another question still to be answered though. Is the 16mm OD > in EN60950 truly correct, or is it really 16mm ID as discussed > earlier?! > > Thanks, > > Jim Eichner > Senior Regulatory Compliance Engineer > Statpower Technologies Corporation > [email protected] > http://www.statpower.com > Any opinions expressed are those of my invisible friend, who really > exists. Honest. > > > -----Original Message----- > From: Price, Ed [SMTP:[email protected]] > Sent: Thursday, October 07, 1999 5:46 PM > To: '[email protected]' > Subject: FW: Conduit entry dimensions > > > Posted for Eric Monk, [email protected] > > > :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-): > -):-) > Ed Price > [email protected] > Electromagnetic Compatibility Lab > Cubic Defense Systems > San Diego, CA. USA > 619-505-2780 (Voice) > 619-505-1502 (Fax) > Military & Avionics EMC Services Is Our Specialty > Shake-Bake-Shock - Metrology - Reliability Analysis > :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-): > -):-) > > > -----Original Message----- > > From: Eric Monk [SMTP:[email protected]] > > Sent: Thursday, October 07, 1999 5:25 PM > > To: WOODS, RICHARD > > Cc: [email protected] > > Subject: RE: Conduit entry dimensions > > > > Hi Richard and group. > > > > ELECTRICAL CONDUIT SYSTEMS IN THE UK. > > > > Electrical conduit systems in the UK were converted during > metrication to > > their nearest metric equivalent. > > > > Sizes refer to outside diameters. > > > > The more common sizes are 20 mm (3/4"), 25 mm (1") and 32 mm (1 ½"). > > > Larger than this there is a tendency to opt for metal trunking. > > > > 16 mm must be based on the old 5/8" conduit which I cannot confirm > > is still available in the UK, until I receive an updated catalogue. > > > > Knockout dimensions are simply a clearance hole for the applicable > metric > > diameter of the conduit size recommended for the application. > > > > The preferred method of termination at an enclosure is to cut and > thread > > the conduit a distance from the box, equal to the diameter of the > > conduit. > > > > Fit an 'internally' screwed coupling (like an oversize sleeve) to > > the end of the conduit and secure it to the enclosure with an > > 'externally' screwed brass bush inserted from inside of the > > enclosure. (bush is the same diameter as conduit thread) > > > > The brass bush has an hexagonal flange larger than the thread to > > tighten onto the enclosure firmly gripping the edge of the knockout > > hole between the brass bush and the coupling and providing earth > > continuity. > > > > The inside edges of the brass bush are chamfered and smooth to > > prevent damage to cable insulation when cables are pulled through > the > > conduit into the enclosure. > > > > Variations are to terminate into a threaded elbow or T-piece if this > is > > dictated > > by space constraints. > > (ie. bush thro k/o into elbow - conduit into elbow) > > > > An alternative is to bring the threaded end of the conduit through > > the knockout and secure it in the enclosure with a locknut on the > > outside and an 'internally' screwed bush on the inside - but this is > > > not considered good practice. > > > > However the termination is accomplished in practice, the knockout > > dimensions > > are the same - > > Close tolerance clearance hole for the diameter of conduit > > specified for the application. > > > > Regards Eric Monk. Technical Director - E M Consulting Ltd. > > > > INTERTest Systems is the trading name of the test laboratory of E M > > Consulting Ltd. > > > > > > ***** Your best support in "TESTING" situations ***** > > ***** INTERTest Systems UK ***** > > ***** International Product Certification ***** > > ***** ONE-STOP-SHOP for ALL testing ***** > > *** PO Box 321 - Bucks HP9 1XJ - England - ++44 (0)1494 673438 *** > > ***** INTERTest Systems UK is the trading name of ***** > > ***** the test laboratory of E M Consulting Ltd. ***** > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). >
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