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So as recent experience shows, 18 - 26 amps max continuous load for
months was a tad optimistic for this unknown brand Schuko wall socket,
which subsequently proceeded to smolder, melt, and deform, almost
causing a fire. I guess you don't think about wall socket power
ratings when your central heating goes out. I've smelled the telltale
smell of something smoldering for a few days, but I couldn't quite
localize it. I checked the cable, and it was warm, but there are a few
warm cables in my house and they're fine, so I assumed this was fine.
I had to dig down to the actual plug and socket (conveniently located
under a few cardboard boxes by the way) in order to find the
following.
One thing that'll "get you" is that this has been running like that
for months now, and only this week has it started making funny smells.
It's good to know about things that'll "get you" like that.
Expectation would be that if it works at first, it'll just keep
working, because how can a plug in a socket go from perfectly fine to
bad enough after months of being used in equal manner? Turns out this
expectation was not correct.
I had to use (VDE) pliers to get the contacts out, and they made a
nice crunchy sound on their way out. Of course I shut off the breaker
first. The contacts are nice and oxidized from the heat, all the way
to blue and brown.
BTW, Schuko are rated to 16A only. Go figure.
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I turned on my air conditioning one day, and heard what sounded like rain, in a bedroom. The 100A breaker was on fire. If I had gone out to turn it off at the meter, the house would have been on fire before I could get back. I had to beat out the flames with my bare hands, before I could turn it off. It had burnt the ends off of the two busbars. When I removed the burnt cover, I discovered that the cheap SOB who installed it had put a used breaker box in. He had worked for the county school board, and he used a lot of used crap around here, before he died. He had outdoor outlets on the horse fencing. He had sliced a lot of used Romex, outdoors with just electrical tape.
So as recent experience shows, 18 - 26 amps max continuous load for
months was a tad optimistic for this unknown brand Schuko wall socket,
which subsequently proceeded to smolder, melt, and deform, almost
causing a fire. I guess you don't think about wall socket power
ratings when your central heating goes out. I've smelled the telltale
smell of something smoldering for a few days, but I couldn't quite
localize it. I checked the cable, and it was warm, but there are a few
warm cables in my house and they're fine, so I assumed this was fine.
I had to dig down to the actual plug and socket (conveniently located
under a few cardboard boxes by the way) in order to find the
following.
One thing that'll "get you" is that this has been running like that
for months now, and only this week has it started making funny smells.
It's good to know about things that'll "get you" like that.
Expectation would be that if it works at first, it'll just keep
working, because how can a plug in a socket go from perfectly fine to
bad enough after months of being used in equal manner? Turns out this
expectation was not correct.
I had to use (VDE) pliers to get the contacts out, and they made a
nice crunchy sound on their way out. Of course I shut off the breaker
first. The contacts are nice and oxidized from the heat, all the way
to blue and brown.
BTW, Schuko are rated to 16A only. Go figure.
|
Its good to understand outlet ratings along with circuits and breakers. Massively loaded test benches tend to suck lots of power. I am careful with power loads and always have been. But also discovered heavy house loads like air conditioning can heat breakers and connections over many years. Need to occasionally retighten the power leads going into breakers and such for very large equipment.? Regards Paul WB8TSL?
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One thing that is not often thought about (or known) is the need to verify the breaker screws and main lugs are torqued to the correct specification. Copper and aluminum will both deform over time and you can wind up with a higher resistance connection with the resulting heat and/or fire.
And especially on newer construction, make sure that any aluminum connections had anti oxidation gel applied.
Hal
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I was walking by a 100A, three phase breaker box at work one day, and I could feel heat from about 18 inches away. It was at a cable TV headend, so we had to bring in a team of electricians to replace the wires and main breaker, starting at midnight. We were down most of the night which was bad enough, but people would have gone nuts if it was daytime with a six hour outage.
On Fri, Jan 14, 2022 at 9:50 AM Harold Foster < halfoster@...> wrote: One thing that is not often thought about (or known) is the need to verify the breaker screws and main lugs are torqued to the correct specification. Copper and aluminum will both deform over time and you can wind up with a higher resistance connection with the resulting heat and/or fire.
And especially on newer construction, make sure that any aluminum connections had anti oxidation gel applied.
Hal
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On Fri, Jan 14, 2022 at 12:33 PM, cheater cheater wrote:
So as recent experience shows, 18 - 26 amps max continuous load for
months was a tad optimistic for this unknown brand Schuko wall socket,
which subsequently proceeded to smolder, melt, and deform, almost
causing a fire.?
BTW, Schuko are rated to 16A only. Go figure.
230/240 VAC countries exist, with approximately equal power ratings. Go figure. Horses for courses -;) Raymond
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Tightening connections: Especially in the case of aluminum wiring, which was popular for a few years, and no doubt still exists here and there.?
Jeremy? N6WFO?
Its good to understand outlet ratings along with circuits and breakers. Massively loaded test benches tend to suck lots of power. I am careful with power loads and always have been. But also discovered heavy house loads like air conditioning can heat breakers and connections over many years. Need to occasionally retighten the power leads going into breakers and such for very large equipment.? Regards Paul WB8TSL?
|
Should not a load of this size, in ¡°continuous¡± [?] use, be hard wired??
So as recent experience shows, 18 - 26 amps max continuous load for
months was a tad optimistic for this unknown brand Schuko wall socket,
which subsequently proceeded to smolder, melt, and deform, almost
causing a fire. I guess you don't think about wall socket power
ratings when your central heating goes out. I've smelled the telltale
smell of something smoldering for a few days, but I couldn't quite
localize it. I checked the cable, and it was warm, but there are a few
warm cables in my house and they're fine, so I assumed this was fine.
I had to dig down to the actual plug and socket (conveniently located
under a few cardboard boxes by the way) in order to find the
following.
One thing that'll "get you" is that this has been running like that
for months now, and only this week has it started making funny smells.
It's good to know about things that'll "get you" like that.
Expectation would be that if it works at first, it'll just keep
working, because how can a plug in a socket go from perfectly fine to
bad enough after months of being used in equal manner? Turns out this
expectation was not correct.
I had to use (VDE) pliers to get the contacts out, and they made a
nice crunchy sound on their way out. Of course I shut off the breaker
first. The contacts are nice and oxidized from the heat, all the way
to blue and brown.
BTW, Schuko are rated to 16A only. Go figure.
|
I had no idea about checking the torque on terminals. How do you check
that? Just a VDE torque screwdriver?
Any clue what the torque specifications are in Europe or Germany on
breaker panels, wall outlets, and Schuko plug contacts?
toggle quoted message
Show quoted text
On Fri, Jan 14, 2022 at 5:26 PM Jeremy Nichols <jn6wfo@...> wrote:
Tightening connections: Especially in the case of aluminum wiring, which was popular for a few years, and no doubt still exists here and there.
Jeremy
N6WFO
On Fri, Jan 14, 2022 at 6:33 AM paulswed <paulswedb@...> wrote:
Its good to understand outlet ratings along with circuits and breakers. Massively loaded test benches tend to suck lots of power.
I am careful with power loads and always have been.
But also discovered heavy house loads like air conditioning can heat breakers and connections over many years. Need to occasionally retighten the power leads going into breakers and such for very large equipment.
Regards
Paul
WB8TSL
--
Jeremy Nichols
6.
|
I do not know if there are published torque specifications for electrical outlet terminals. One would think they would exist somewhere but I¡¯ve always used ¡°tight enough¡± as my guide.
I had no idea about checking the torque on terminals. How do you check
that? Just a VDE torque screwdriver?
Any clue what the torque specifications are in Europe or Germany on
breaker panels, wall outlets, and Schuko plug contacts?
On Fri, Jan 14, 2022 at 5:26 PM Jeremy Nichols <jn6wfo@...> wrote:
>
> Tightening connections: Especially in the case of aluminum wiring, which was popular for a few years, and no doubt still exists here and there.
>
> Jeremy
> N6WFO
>
>
> On Fri, Jan 14, 2022 at 6:33 AM paulswed <paulswedb@...> wrote:
>>
>> Its good to understand outlet ratings along with circuits and breakers. Massively loaded test benches tend to suck lots of power.
>> I am careful with power loads and always have been.
>> But also discovered heavy house loads like air conditioning can heat breakers and connections over many years. Need to occasionally retighten the power leads going into breakers and such for very large equipment.
>> Regards
>> Paul
>> WB8TSL
>>
> --
> Jeremy Nichols
> 6.
>
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a lot of times the
spec is listed on the label of breaker, sometimes in the panel
for the lugs like for mains entrance. I have used standard
torque wrenchs w/ proper driver.
Here in the USA one more mfg of bad breakers Zinsco ( never
trips) from the late 1940's thru at least the 1960s , I have
several that I took to work put on the test rack 15A and 20A
that tripped between 30 and 67A. !!!!? talk about unsafe and
these were on 14 and 12Ga wire feeding the house....If they are
not on the replace on sight list they should be....I was lucky
to have testing capabilities.
I rewired my house using a pair of NEW 100A breakers ( back in
1992) for mains, they test 150A...btw they hold at 150A for 1
hour plus, trip at 155A and 160 in 50 sec. ( at least they
trip!) I did go to a sub panel ( proper size both wire and panel
for 150A) for distribution using Siemans? breakers all tested
spot on.
I generally re-torque/check everything every 15yrs...they do get
loose!
¸é±ð²Ô¨¦±ð
On 1/14/22 3:38 PM, cheater cheater
wrote:
toggle quoted message
Show quoted text
I had no idea about checking the torque on terminals. How do you check
that? Just a VDE torque screwdriver?
Any clue what the torque specifications are in Europe or Germany on
breaker panels, wall outlets, and Schuko plug contacts?
On Fri, Jan 14, 2022 at 5:26 PM Jeremy Nichols <jn6wfo@...> wrote:
Tightening connections: Especially in the case of aluminum wiring, which was popular for a few years, and no doubt still exists here and there.
Jeremy
N6WFO
On Fri, Jan 14, 2022 at 6:33 AM paulswed <paulswedb@...> wrote:
Its good to understand outlet ratings along with circuits and breakers. Massively loaded test benches tend to suck lots of power.
I am careful with power loads and always have been.
But also discovered heavy house loads like air conditioning can heat breakers and connections over many years. Need to occasionally retighten the power leads going into breakers and such for very large equipment.
Regards
Paul
WB8TSL
--
Jeremy Nichols
6.
|
Rene¨¦, thank you for the input from someone who has ¡°been there.¡±
-- Jeremy Nichols
6.
|
Just tighten the screw a bit if its loose.
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Make sure the wire hasn't overheated, first. If it has, the lug needs to be replaced, and the damaged end of the wire trimmed off.
Just tighten the screw a bit if its loose.
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Manufacturers generally provide an installation sheet for their products, but many wiring devices don't come with the sheet.? I use Hubbell a lot here in the US and have had excellent service from them.? I have seen a near disaster with a 40A range plug and socket that were melted and partly burnt but amazingly didn't catch fire even with 4" of insulation melted on one of the wires outside of the receptacle box in the wall.? That receptacle may well not have been a Hubbell, I could not read any markings on the toasted remains.? You don't get any closer to disaster than that one, but good materials selection kept it from burning.? It failed because the cord was a bit too short for the way the range was positioned and the plug worked its way out until it started arcing.
? As for torque, One of the common Hubbell PD2437 15A straight prong "standard" US plugs (lots of people call them cord caps) is spec'd at 12 inch-pounds of torque in the installation document.? NFPA requires they be torqued to spec.? I have found that many electricians and DIY types don't bother and tend to over-tighten them to the point of damaging the threads at times.? Be sure to consult the right data sheet for the connector type, they of course vary.? I recently saw some spring lock devices in Hubbells twist-lock? line that use a wedge type device to secure the conductors, and since there is no screw they don't need to be torqued and comply with NFPA rules.? Those would be a lot faster to install but I have always shied away from "stab backs".? There wasn't enough contact area to make me confident in the connection's long-term integrity.? Dirt and oxidation happen.? These new spring lock ones look to be different enough to investigate in the future.
? The standard 15A and 20A 120Vac home electrical circuits in the US are a bit disconcerting.? Not only do we not use fused plugs on our power cords, you can plug a 15A style plug into a 20A receptacle if it is the type with a T-shaped straight and twisted prong slot.. It would be very easy to grossly overload an 18AWG cord for example.
? The craziest thing I ever did was lay a nice metal cased Wiremold power strip on my welding table to run a fan.? I didn't give it a second thought.? While welding a large item at about 125Amps I accidentally knocked the magnetic ground clamp loose from the workbench.? The ground wire in the cord to the power strip instantly burned a spiral through the jacket of the 15' power cord on the power strip.? That's one I won't forget.
Clay Scott
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This is why the british idea ofhaving a fuse in the plug is good.? Even if the spur was fused for 16A at the board it may not blow for a small oveload. With the fuse clipped directy to the pin any contact heating also heats the fuse, effectively lowering it's fusing point. and rviding a bit of additional protection against small overloads. It's not desigind to do this but it does.
Robert G8RPI
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I rebuilt a repulsion-start motor from circa 1910 a few months ago, and had it fail after about 7 starts when I was testing it.? There was no data plate on the unit, and I had never worked on one of them before.? The cord was original (cloth-wrapped), and was so bad I just cut it off right away and replaced it with the first round type I pulled out of the cord bucket without thinking about it.? When the motor failed to start, I thought a winding had failed, so I shelved the motor.? About a week later, I was thinking about, and realized that the leads coming out of the motor were heavy, and the cord I had used was kind of light...? ? ? ? ? ? Yup, upon dissection, the junction between the wire and one of the plug prongs had melted.? I didn't think the motor would draw so much power unloaded, but the huge motor leads should have been a warning!?
-Dave
On Saturday, January 15, 2022, 02:28:22 AM PST, freshndaire <fanman@...> wrote:
Manufacturers generally provide an installation sheet for their products, but many wiring devices don't come with the sheet.? I use Hubbell a lot here in the US and have had excellent service from them.? I have seen a near disaster with a 40A range plug and socket that were melted and partly burnt but amazingly didn't catch fire even with 4" of insulation melted on one of the wires outside of the receptacle box in the wall.? That receptacle may well not have been a Hubbell, I could not read any markings on the toasted remains.? You don't get any closer to disaster than that one, but good materials selection kept it from burning.? It failed because the cord was a bit too short for the way the range was positioned and the plug worked its way out until it started arcing.
? As for torque, One of the common Hubbell PD2437 15A straight prong "standard" US plugs (lots of people call them cord caps) is spec'd at 12 inch-pounds of torque in the installation document.? NFPA requires they be torqued to spec.? I have found that many electricians and DIY types don't bother and tend to over-tighten them to the point of damaging the threads at times.? Be sure to consult the right data sheet for the connector type, they of course vary.? I recently saw some spring lock devices in Hubbells twist-lock? line that use a wedge type device to secure the conductors, and since there is no screw they don't need to be torqued and comply with NFPA rules.? Those would be a lot faster to install but I have always shied away from "stab backs".? There wasn't enough contact area to make me confident in the connection's long-term integrity.? Dirt and oxidation happen.? These new spring lock ones look to be different enough to investigate in the future.
? The standard 15A and 20A 120Vac home electrical circuits in the US are a bit disconcerting.? Not only do we not use fused plugs on our power cords, you can plug a 15A style plug into a 20A receptacle if it is the type with a T-shaped straight and twisted prong slot.. It would be very easy to grossly overload an 18AWG cord for example.
? The craziest thing I ever did was lay a nice metal cased Wiremold power strip on my welding table to run a fan.? I didn't give it a second thought.? While welding a large item at about 125Amps I accidentally knocked the magnetic ground clamp loose from the workbench.? The ground wire in the cord to the power strip instantly burned a spiral through the jacket of the 15' power cord on the power strip.? That's one I won't forget.
Clay Scott
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Several insurance companies employed by my clients here in the US require periodic inspection of the service entrance panels and other AC circuitry with a FLIR thermal imager to ascertain that there is no potential for overheating and a fire.? The real advantage to this is that it can see trouble spots that may not seem obvious to the casual passerby.
?
As for things running warm to the touch it is best to check outlets and other apparatus to make sure that gradual heating is not causing oxides to form on the contact surfaces thereby increasing resistance which often times will cause the heating to increase exponentially until failure or fire occurs.? A small amount of heating may be normal given the current of a device but it can also cause an increase in problems if it gets out of hand.
?
There are fastener torque requirements for service entrance panel hardware but seem to be applied mostly on an ad-hoc basis.? Although torque requirements have been set forth in both several states as well as in the National Electrical Code I have not come up against any electrical inspectors who have brought the issue up.? This may not be the case for extremely high current service applications.
?
?
?
?
Also keep in mind that the reliability of the connection is only as good as the quality of cleanliness of the connection interface.? Any increase in joint resistance may eventually cause trouble.
?
AN earlier mention was made of aluminum wiring being ¡°¡popular for a few years.¡±? It¡¯s surprising to see that many utility companies still use aluminum drops when connecting between the poles and customer premise weatherheads.? As for internal wiring any you will probably find a preponderance of aluminum used in homes built between 1965 and 1972.? Use of it is still allowed if the proper installation procedures are followed.
?
Personally I live in a 72 year-old home with copper wiring.? The only downside is that the wiring insulation is of the rubber/cloth type but fortunately the installation is not of the knob-and-tube type.? The wiring is of a 2-wire NM type (without ground) and has been going through a gradual update to 3-wires as remodels occur.
Aside from all of this, make sure that the batteries in your smoke detector(s) are in good shape.
?
Greg
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Greg wrote, in part:
¡°?As for things running warm to the touch it is best to check outlets and other apparatus to make sure that gradual heating is not causing oxides to form on the contact surfaces thereby increasing resistance which often times will cause the heating to increase exponentially until failure or fire occurs.??A small amount of heating may be normal given the current of a device but it can also cause an increase in problems if it gets out of hand.¡±
We had a fire in our home due to exactly that situation. The pressure switch on our water pressure tank gradually became corroded until it could not pass enough current to start the pressure pump. As a consequence, the tank kept ¡°calling for water¡± but there was none.?
The current that turned into heat in the switch contacts eventually caused the switch assembly and its plastic cover to burn. Fortunately, this set off a smoke alarm, waking me at (of course) 0400. I put out the fire with an extinguisher and called 911 for backup. Minimum damage, and when I replaced the pressure switch I added a thermal fuse.?
I later discovered that the pressure pump had gotten hot enough that the plastic piping was severely bulged, although it did not fail.?
-- Jeremy Nichols
6.
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Michael A. Terrell
Harold Foster
Jeremy Nichols