Valve radio failed pat test!

[Tim]

Hi all.
I have a radio in the tea room at the local BT exchange, which I have repaired and left on top of the fridge for the lads to use. It is a Philips B3G63A, AC set with VHF.
I came in one day to find a "Failed" sticker applied and the mains plug cut off.
As well as being surprised and horrified(that I may have let an unsafe radio through) I was also mystified.
I tested the set in question with a megger. Earth wire in mains cord OK, and continous to chassis. No detectable path from either live or neutral to chassis.(Tests made with on switch ON)
Why did it fail?
Something else mysterious. The volume knob was slightly pulled off(just far enough for a crocodile clip?) so maybe the inside of the concentric control is somehow insulated from chassis. I haven't confirmed this yet, but will look into it.
I will leave them a melted(but working) Fidelity Rad 18 as REVENGE!!
What does the team think?
Tim

[Station X]

The trouble with old radios, even AC ones, is that they don't fit any of the classes of appliance defined for PAT Testing (sic). A fridge or washing machine is easy. You clip the earth lead to the exposed metalwork and carry on from there. Double insulated appliance such as electric drills are easy as well. No earth test needed. Old radios don't fit either category. The tester probably treated the shaft as exposed metalwork, hence the failure.

The trouble is that testers just steal the mains plug or fuse and stick a failed sticker on without further explanation. After an attempt was made to rip me off by failing a perfectly good heater "I can sell you a new one at a bargain price guv" I started using another tester who issues a proper test report with readings for every appliance.

Graham.

[G0PKH - Pete]

Hi Tim


Like you, I would find the fact that the volume knob was slightly pulled off suspicious.

I would tend to think that maybe the earth bonding test was carried out between the earth lead in the plug and the pot spindle, rather a solid chassis connection.

This is likely to be the reason it failed, as the resistance between the spindle and chassis would not be particularly good.

This rather questions the competance of the person doing the testing, were there any other more convenient places to attach the PAT tester to chassis directly, I wonder.

Pete

[radiomanic]

PAT testers are notorious for failing good equipment. They are made of course to be opperated by a 'nominated' employee so that an employer can ensure his equipment comply's with the Electricity at Work Act. 1989.Pass/Fail parrameters are pre set by the manufacturer. After an afternoons training this bod is now an electrical engineer. So expect such results when non standard items are left lying around.
Put it down to one of lifes little quirks and reinstate the former set in its rightful place.


Frank

[Station X]

The trouble is that vintage radios don't easily fall into one of the classes of equipment defined for PAT Testing (sic).

They're not Class 2 appliances because they're not double insulated and marked with the double concentric square symbol.

They're not Class 1 appliances either, because they don't have an earth connection.

Therefore they need to be converted to Class 1 by fitting a 3 wire flex and plug with the earth lead connected to the chassis. Of course this should only be done with AC sets fitted with an isolation transformer.

Having converted a radio to Class 1 the question is how to test it. A connection to the chassis, by croc clip or probe, is needed so that the continuity of the earth lead can be tested along with the insulation resistance from the live and neutral wires to earth.

Many sets including the set which is the subject of this forum probably don't have a convenient point to connect the tester to. This might explain why the operator connected his croc clip to the pot spindle.

Perhaps the solution where sets have to be PATed is to provide a prominent earth terminal for connecting the tester to.

You can generally tell using a normal meter whether a set is likely to FAIL a PAT, but it is more difficult to tell if it will pass. High voltage is needed to test the insulation resistance and high current to test the earth continuity.

Graham.

[Sideband]

We often get calls from schools and hotels saying that one or other of our TV's have failed a PAT test. Quite simply a 'sparks' with no knowledge of TV has gone in to test everything with a plug on it. Quite simply, you cannot test a TV with a PAT tester and I suspect that this applies to radio's particularly of the vintage type for the reasons given by Graham. So I wouldn't worry too much about the radio having failed. Trouble is you can't convince the 'top brass' so probably better to keep them happy with the Fidelity and use the vintage set quite safely yourself.



Rich.

[evingar]

Put it down to one of lifes little quirks and reinstate the former set in its rightful place.

As the mug that got lumbered with mains safety testing at our place, I would not recommend this course of action.

The actuality will not then tally with the database - alarm bells will ring, klaxons will wail, dire warnings will be issued, a "blame fest" will breakout and a*ses will be kicked around when the nominated ISO 9000 man picks that particular item to check that "procedures" are being followed accurately-

[stephanie]

What I wanna know is why the Mr. X who was doing the testing decided to go after someone's personal radio?

I'd certainly be screaming.

No, we don't have such things in the USA, to my knowledge..

[evingar]

What I wanna know is why the Mr. X who was doing the testing decided to go after someone's personal radio?

I'd certainly be screaming. [img]file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5 Cmsoclip1%5C01%5Cclip_image001.gif[/img]

Hi Stephanie

Over here, in a lot of companies, personal mains powered equipment like that would not be allowed - period.

The company I work for does permit such personal equipment but it must be added to the asset register and be scheduled for a mains safety test in line with company policy - If it fails, I will attach a red "do not use” label and physically prevent the equipment from being connected to the supply, although our company is small enough for me to “have a word” with the owner of the personal equipment before butchering his property.

I am duty bound in that position to do so. It does not matter who owns the equipment, it must still comply with the company safety policy. I am not quite sure what I would have done about that radio - it would depend on the design, case condition etc.

I love old valve equipment but would be uneasy at having such equipment at work because of the risk of it being left on unattended over night accidentally - if it was, it would present something of a fire hazard IMHO. This is a different issue from that of mains safety and would be covered by the company Safety Officer - not necessarily the same individual that does the mains safety testing.

The Safety Officer assesses risk within a company, if a fire or electrocution were to be caused by such equipment, the company could be in deep trouble from the Health and Safety Executive (Govt body) if it transpired such equipment had not been assessed for risk and is under the companies mains safety remit, with documentary evidence to prove this. There may also be “issues” with the company insurance company.

Writing all this down sounds cr@p and "jobs worth" but it is the way of the world over here - It's too risky not to comply with this stuff

[oldeurope]

Good morning,

"No, we don't have such things in the USA, to my knowledge.."

In the USA you have only 117V AC in Europe 230V AC.
So a safety test is neccessary here.

I have no problems with the test. The sets are in most cases class 2.
Changing it to class 1 causes often hum.

It is importand to make the isulation test for a long time ca. 10 minutes
to find out bad "Y" caps.

If a nob or the back cover is missing the set is not isulated and fails.
If you want to use a set that failt the test, connect it via
an isulating transformer. This is the best and safest solution.

Importand: Only one set can be connected to the transformer output!


Kind regards
Darius

[Heatercathodeshort]

The Worlds gone mad! All this lunatic 'testing' just produces 'agencies' and jobs worths and EXPENSE. Different utility I know but I had two perfect gas fires written off by the gas board MID WINTER in a flat I rented to a young couple. They also informed me the backs were not 'up to modern standards'. It cost me £500 for the work. They cut the gas supply off and placed DANGER DO NOT USE stickers on the fires. The old fires [CANNON] were stored in my garage and later tested by a retired gas board engineer who informed me they were well up to standard. To add insult when they checked the system the following year [safety check] they declared the backs they had fitted less than a year before were a fire hazard! This waste of good electrical and gas appliances must cost industry, hospitals and local authorities billions every year. JOHN.

[mikelect]

OT closed