Safety Recall

[Phil Allison]

** Hi,

came across this warning on the Yamaha Music web site recently:

http://au.yamaha.com/en/news_events/proaudio/product-recall-2011/

" Hazard Due to the defect products can cause death or injury to the user "

Sounds pretty serious.

But how can an AC plug be wired wrong and the unit still work and not trip
ELCBs ??



.... Phil

 

[Phil Allison]

"Rheilly Phoull"

Well there are still some older homes without the protection,

** All the products concerned are for professional / commercial use.

If they tripped ELCBs - owners would be unable to use them at all making
the re-call redundant.

Also note that some of the items ( the powered speakers ) have standard 3
pin IEC inlets.

None of the items are class 2 or double insulated, AFAIK.



.... Phil

 

[Phil Allison]

"kreed"

About the only scenario that comes to mind is the earth wire not being
connected,

** My initial thought - but that is very unlikely across all the examples.


though if some of the items have IEC inlets, then the wiring fault
might be in the unit itself and not the IEC cord.

** Has to be - but the notice says the plug needs rewiring.


Of course, they might have copped a bad batch
of IEC cords

** With what fault?

It cannot be neutral-earth swapped.

It is possible that they chopped the foreign plug off the (non-IEC)
cords, installed an Australian plug, and somoene messed up the job,


** Very unlikely and what is the actual mistake ????????



.... Phil

 

[Phil Allison]

"kreed"

I do see what you mean, 2 different types of cords, and there is a
recall on both types.

** No - there is a recall on the products.


Only faults I can think of that would be hazardous, but the gear would
still work would be no earth connection at the plug,


** You said that already.

or earth and neutral both connected to the neutral pin,

** Still trips ELCBs in a moment.


as it says "plug may have been wired incorrectly" and "rewire the
mains plug if faulty"

** Wrong to take that literally.

It was written by some moron in marketing you know.


The units could have come from China (or where ever they are made)
with the Australian plugs wired by hand there too.

** I have not seen a hand wired plug on anything from Asia in decades


If they didn't
have sufficient ready made cords, they may have hand wired a few plugs
onto existing ones to get the shipment ready to deadline.

** IEC leads are prescribed items, each component must be approved ( and
labelled with the approval code number) for use in Australia - you cannot
just dodgy one up from bits.

Moulded ones with Aussie plugs ( same as China) cost tiny amounts compared
to paying someone to modify one with the wrong plug.



.... Phil

 

[Baron]

kreed Inscribed thus:

Finally another fault I found recently. When cutting an IEC lead to
hard wire it into a terminal block inside a cabinet, found that there
was no earth wire for about 8" inside the cord, but just a hole next
to the other 2 wires where it should have been. IT could not have
been removed at any stage after manufacture, as the outer insulation
was intact with no cuts or other damage visible. Also it was missing
in the middle of the cable, not at an end.


Were lucky to have cut it in the right place or this might not have
ever been discovered. I have never in nearly 40 years ever seen this
before in any 3 core flex cable that I have worked with.

This was a Japanese made cord probably of 1980s vintage, very light
grey in colour.

Odd this should come up ! I've just replaced the mains lead on an 800W
bench circular saw. Intermittent fuse blowing. Turns out that the
mains lead has had the live and earth wires migrate through the
insulation where the lead had been folded when the saw was originally
packaged.

I admit that I had to cut the cable in short chunks to actually find
where it was shorting. At each bend in the cable the two conductors
had migrated through the insulation.

I've put a new mains lead on and all is fine now. The original lead was
very hard, stiff plastic, not soft and flexible like you would expect.
I also found that the blue insulation was bonded with the outer jacket
and the brown live insulation, making it impossible to strip the
insulation from just one wire without damaging the others.

 

[Adrian Jansen]

Odd this should come up ! I've just replaced the mains lead on an 800W
bench circular saw. Intermittent fuse blowing. Turns out that the
mains lead has had the live and earth wires migrate through the
insulation where the lead had been folded when the saw was originally
packaged.

I admit that I had to cut the cable in short chunks to actually find
where it was shorting. At each bend in the cable the two conductors
had migrated through the insulation.

I've put a new mains lead on and all is fine now. The original lead was
very hard, stiff plastic, not soft and flexible like you would expect.
I also found that the blue insulation was bonded with the outer jacket
and the brown live insulation, making it impossible to strip the
insulation from just one wire without damaging the others.

Sounds like it was subjected to enough heat to partially melt both the
inner insulation and the outer jacket. Poor quality insulation, with a
low melting point ?

 

[Phil Allison]

"Baron"

I've just replaced the mains lead on an 800W
bench circular saw. Intermittent fuse blowing. Turns out that the
mains lead has had the live and earth wires migrate through the
insulation where the lead had been folded when the saw was originally
packaged.

** Though it sounds frightening, the only likely result of the conductors
inside an AC power cable coming into contact is fuse blowing, circuit
breaker tripping or ELCB tripping.

After all, that is what they are there for....


..... Phil

 

[terryc]

Sounds like it was subjected to enough heat to partially melt both the
inner insulation and the outer jacket. Poor quality insulation, with a
low melting point ?

Folded too soon after construction?
Or as you suggest, the cable just wasn't up to the job of carrying the
current.

 

[Baron]

Adrian Jansen Inscribed thus:

Sounds like it was subjected to enough heat to partially melt both the
inner insulation and the outer jacket. Poor quality insulation, with a
low melting point ?

Yes I completely agree with you !
Trouble is, you don't find out there is a problem until you have a
problem. If you know what I mean...

 

[Baron]

Phil Allison Inscribed thus:

"Baron"



** Though it sounds frightening, the only likely result of the
conductors inside an AC power cable coming into contact is fuse
blowing, circuit breaker tripping or ELCB tripping.

After all, that is what they are there for....


.... Phil

I do agree ! The question that springs to mind, is what if the earth
conductor was OC or partially missing. There is/was the risk that the
whole saw could have become live. Also with a moulded on plug there
wouldn't be any guarantee that the insulation wasn't compromised
inside.

 

[Baron]

terryc Inscribed thus:

Folded too soon after construction?
Or as you suggest, the cable just wasn't up to the job of carrying the
current.

The cable has been binned and replaced now.

A point that occurs to me is, since the conductors are welded to the
pins inside the molded plug, could the wire itself have become the
return path for the welding current. If so that could explain the way
the insulation was bonded to the jacket and other wires. Possibly the
wires could have become hot enough to cause the migration seen.

Either way its a potential hazard that would be completely hidden from a
user until it caused a problem.

 

[terryc]

Yes I completely agree with you !
Trouble is, you don't find out there is a problem until you have a
problem. If you know what I mean...

Unlesss you just happen to pick the cable up at the right moment and
realise there is a hot spot.

BTDT and snip snip nip to the copper recycling bin. Most you just smell
or wonder where that smoke is coming from.

 

[Baron]

terryc Inscribed thus:

Unlesss you just happen to pick the cable up at the right moment and
realise there is a hot spot.

In this case the first sign of any problem was a blown fuse ! Following
replacement some time passed before the fuse blew again. Each time the
machine worked satisfactorily following fuse replacement. It was only
the last time the fuse blew almost immediately that it was realised
that flexing the cable was the culprit.

BTDT and snip snip nip to the copper recycling bin. Most you just
smell or wonder where that smoke is coming from.

Yes it did end up in the scrap cable bin. I don't recall that there was
any smoke or oder at all.

 

[Phil Allison]

"Baron"
Phil Allison

I do agree ! The question that springs to mind, is what if the earth
conductor was OC or partially missing. There is/was the risk that the
whole saw could have become live.

** That is what ELCBs are for......


.... Phil

 

[JW]

Finally another fault I found recently. When cutting an IEC lead to
hard wire it into a terminal block inside a cabinet, found that there
was no earth wire for about 8" inside the cord, but just a hole next
to the other 2 wires where it should have been. IT could not have
been removed at any stage after manufacture, as the outer insulation
was intact with no cuts or other damage visible. Also it was missing
in the middle of the cable, not at an end.

A few months ago I cut off the end of an IEC cord to put spade lugs on it
for testing a 6031A power supply. Imagine my surprise when the inside
conductors were 26ga wire. The cords had a 10A 250V rating on it and a UL
stamp, likely forged.

 

[Baron]

Phil Allison Inscribed thus:

"Baron"
Phil Allison


** That is what ELCBs are for......


... Phil

Yes, You're right ! I was thinking along the lines of a home workshop
without mains/master ELCB protection device. Which I must confess, I
don't have. :-( Though I do have one on the extention cable that I
use outside for the mower.

 

[Adrian Jansen]

I think it is a good idea to do the "electric jug test" on these
things. The cable will heat up
real quick in this case, and can be easily spotted as insufficient
cross sectional area of conductor.

Maybe its about time some bureaucrats thought about testing some of the
stuff they allow as imports, and actually reject some, rather than just
inspect the stamps and pseudo-ratings on the import forms. They are
quick enough to test local product, and make mfgs jump through all sorts
of hoops to get approval to make them. But I guess they dont want to
upset the countries they import from too much.

 

[Phil Allison]

"Adrian Jansen"
JW

Maybe its about time some bureaucrats thought about testing some of the
stuff they allow as imports,

** It is up to people who find such leads to report the matter to the
relevant state authority.

JW does not say where he got the IEC lead - maybe he imported it himself
( eg came packed with some item direct from China) and so he has only
himself to blame for not checking it out immediately.

A few years back, the topic was done to death on this NG and not a single
example was ever given of defective IEC leads being sold here in Australia.


..... Phil

 

[JW]

"Adrian Jansen"
JW


** It is up to people who find such leads to report the matter to the
relevant state authority.

JW does not say where he got the IEC lead - maybe he imported it himself
( eg came packed with some item direct from China) and so he has only
himself to blame for not checking it out immediately.

Unfortunately, I'm not sure where it came from as there's dozens of power
cords all around here, but I'd bet the original source was from China as
well.

 

[Phil Allison]

"kreed"

Unfortunately, I'm not sure where it came from as there's dozens of power
cords all around here, but I'd bet the original source was from China as
well.

I have seen a few, all came with Items bought off Australian Ebay
sellers IIRC and 2 of them had US plugs

Try it on an electric jug, if you want some entertainment. Might make
a good you tube video also.


** Been there, done that with a dodgy IEC lead that came from in India with
a repair job.

At 11 amps, volumes of smoke poured and conductors poked out through the
plastic.

Not only was the gauge very light, but the conductors were some strange
alloy with several times the resistance of copper.

My report of the finding started am LOOOOONG debate here with Ross Herbert
taking up the cudgel ad the WA authorities getting in on the case.



.... Phil