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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 11th Jul 2021, 3:59 pm   #1
newlite4
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Default Black & Decker PI utility drill

Just checking over this mid fifties 1/4" drill and although working, it is failing PAT on insulation. Upon dismantling, there are two Dubilier 0.005uF/250VAC caps in each supply feed to the motor. They are both clamped onto the case with P clips (probably feed through types). The cap in the neutral feed measures 11Mohm and the cap in the live feed measures 1.2Mohm (it would be this cap that is flipping the PAT tester into "insulation fail").
Do I need to replace these caps for interference suppression, or could I just permanently remove them or insulate them from case in order to pass PAT?
Neil
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Old 11th Jul 2021, 4:41 pm   #2
The Philpott
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Default Re: Black & Decker PI utility drill

For a customer, workplace or personal use?
Insulating them from the case or removing them may pass PAT (being a non-invasive test) but then you've got the uneasy feeling that you've changed the tool from it's original spec..

Dave
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Old 11th Jul 2021, 4:48 pm   #3
newlite4
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Default Re: Black & Decker PI utility drill

Hello Dave, this would ultimately end up on my stall, so I need to ensure that even though it is a vintage collectible and may not be used, it needs to be made safe to use if the next owner wishes to demonstrate it. I would never knowingly sell dangerous goods and always PAT test earthed items.
Neil
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Old 11th Jul 2021, 4:53 pm   #4
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Default Re: Black & Decker PI utility drill

The issue could be that (assuming said drill is earthed) AFAIK 1.2Mohm is allowed for Class I appliances (earthed) but not fir Class II (unearthed) metal cased appliances, it certainly was that the limits on our older Fluke 6200 were 1Mohm for Class I and 2Mohm for class II appliances.
Naturally as some of the cheaper PAT machines only give a pass/fail (like the Seward Prime Test 50) they have to be set to pass only at the higher 2Mohm limit and as such will fail some devices that would otherwise pass.
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Old 11th Jul 2021, 5:00 pm   #5
paulsherwin
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Default Re: Black & Decker PI utility drill

From a safety point of view it would be simplest to remove them, but that isn't going to make any owner popular with his neighbours. Can't you just replace them with a couple of X2s?
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Old 11th Jul 2021, 5:09 pm   #6
newlite4
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Default Re: Black & Decker PI utility drill

Yes Paul, replacement with X2 caps would be the ideal, problem is that the original caps are designed specifically for this application. The outer body (grounded pole) is fixed to the appliance case whilst the supply feeds through the centre which is the inner pole of the cap, this makes it fairly safe to fit as the mechanical integrity prevents any danger of the supply touching the case.
Neil
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Old 11th Jul 2021, 5:23 pm   #7
paulsherwin
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Default Re: Black & Decker PI utility drill

The supply will touch the case if the caps fail short circuit, which is basically what's starting to happen.

You should be able to sort it out with a bit of shrinkwrap.
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Old 14th Jul 2021, 8:55 am   #8
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Default Re: Black & Decker PI utility drill

Well, it is all back together, with some challenges! I had some LCR class Y 250VAC caps in stock (these are the type that you fit from live and neutral to earth whereas class X fit between live and neutral) which were suitable to fit in the tight space behind the switch. Using heatshrink and lengths of stiff tinned copper wire, I was able to craft two capacitor modules that were not dissimilar to the original types. On test the drill passed PAT and with an AM radio next to it whilst running there was no interference.
Neil
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