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Author Topic: Lamp Module Melt down  (Read 6921 times)

Brian H

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Re: Lamp Module Melt down
« Reply #15 on: December 21, 2009, 06:43:16 PM »

The module is good for 15 amps pure resistive. Problem is cold bulbs and surge current.

I looked at a few other modules from other manufacturers. They all limited incandescent loads to a lower wattage.

ACT RP124 15 amps resistive; 600 watts incandescent.

Insteon ApplianceLinc 15 amps resistive; 480 watts incandescent or inductive.

Wayne Dalton ZWave Module HA-02WD 15 Amps resistive 8.5 Amps tungsten bulbs.
« Last Edit: December 21, 2009, 07:07:28 PM by Brian H »
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mike

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Re: Lamp Module Melt down
« Reply #16 on: December 21, 2009, 06:49:56 PM »

Good catch on the poor connection at the plug tabs themselves.  

We recently moved our small business to a city from home and had a fire dept. sneak inspection - seems they inspect all businesses for safety in cities...  anyway, we quickly were dinged for all extension coreds - not allowed!  period!  the small multi connector end you plug into apparently is cause of a majority of electrical fires we learned!  a power strip is ok but not an extension cord.  good info.  your experience seems to back this.

second, I had a x10 small 5 amp noise filter catch fire and shoot 12" flames that charred the 2x4 wall stud next to the outlet - for the same reason as yours!  NO INTERNAL FUSE AND BAD 120V TAB CONNECTION into the regular outlet!  pictures showed the filters 120v male prongs must of heated from bad 4.5amp load and burned the pcb right away - luckily I was in the room at the time a month ago and saw it happen - used 1/2 a fire extinguisher to put out the flames!  subsequently removed ALL x10 noise filters and replaced with smart home better quality and fused units.  my pictures look like yours - will send if anyone wants to see.
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Brian H

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Re: Lamp Module Melt down
« Reply #17 on: December 21, 2009, 07:09:53 PM »

The LM465 also has one of what looks like the exact same coil in it as the XPPF has three of.
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rperego

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Re: Lamp Module Melt down
« Reply #18 on: December 21, 2009, 11:36:43 PM »

I agree the rating is strange.  An extra 10 amps for inrush seems like a lot.
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-Bill- (of wgjohns.com)

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Re: Lamp Module Melt down
« Reply #19 on: December 21, 2009, 11:46:14 PM »

Never measured it myself, but my understanding is that an incandescent filament is nearly a dead short when power is first applied and increases in resistance as it heats up.

 >!
« Last Edit: December 21, 2009, 11:47:45 PM by -Bill- (of wgjohns.com) »
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HA Dave

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Re: Lamp Module Melt down
« Reply #20 on: December 22, 2009, 11:49:12 AM »

You guys are talking in AMPS... like making heat really requires that much. I know the little halogens that I use in my lawn lamps get really warm (will take your skin off). And they only use 10 WATTS at 12 Volts. That's not even a whole [1] AMP... is it?

I heard on one of the news channels that 10,000 homes will suffer damage or be destroyed this December due to Christmas lights (and there misuse). That sorta makes it sound like it might not be all that hard to do.
« Last Edit: December 22, 2009, 11:53:41 AM by Dave_x10_L »
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gator.bigfoot

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Re: Lamp Module Melt down
« Reply #21 on: December 22, 2009, 12:43:20 PM »


Power (Watts)=Voltage (E) X Current (I) 

This is for purely resistive loads.  When you get into inductive loads then it is a whole new ball game.  But for the most part most home applications will still follow this formula.

So in you case 10W/12V = 0.833 amps

One string of 70 (7 watt) lights 7X70= 490 watts        490 watts/110 volts= 4.45 amps

One 100W light bulb                                              100/110 = 0.9 amps

Four Halogen 50W bulbs                                         200/110 = 1.8 amps

Most fires occur because extension cords are overloaded.  Most extension cords are not rated for more than a 10 amps.  They use 16 or 18 gauge wire or even smaller.  Check your load tables

Wire    Current max at 110V
gauge
22       5A   
20       7.5A
18       10A
16       13A
14       17A
12       23A

With extension cords comes another danger.  Frayed wires.  Most extension cords are in poor shape.  They are already poorly made, with poor quality connectors.  Then you add your load to it, walk on it, the kids run their toys over it, it is hidden under a carpet.  It's no wonder there are fires. It is actually more of a miracle that there are not more.

Now we have another factor involved here and that is the length of the wire.  This adds resistance.  Resistance adds extra load.  All of that turns into heat.  Which needs to dissipate.  Too much heat equals fire. 

Years ago I worked for Square D.  The first thing one of my co-workers showed me was a suitcase (for trade shows) with a transformer in it and switch a receptacle and a bunch of breakers.  The transformer was connected to a 110 volts and the output voltage  of the transformer was very low(2 volts).  The current output of the transformer was around 200 amps.  The display was intended to show how fast different breakers trip.  By inserting a paper clip into the outlet (dead short) the switch was turned on.  With every single breaker manufacturer on the market the paper clip caught fire.  All but with the Square D breakers.  With theirs you could plug the paper clip in the outlet while the power was turned on.  Now granted not everyone will do this and the test was biased toward their breakers, but the intent of the display was to show what can happen with a frayed extension cord.  Once you get into very few wires and a high load it will draw a lot of extra current.  Enough to start a fire, as the paper clip demonstrated.  Needless to say I went home and switched out my breakers.

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JeffVolp

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Re: Lamp Module Melt down
« Reply #22 on: December 22, 2009, 01:13:05 PM »

Those pre-lighted Christmass trees can pull a LOT more power than you expect.

We had always used a lamp module for the Christmas tree lights back East.  6 years ago we bought a large fake tree from Costco.  Not thinking that those little lights would pull much power, I plugged it into the lamp module like before.  The lamp module worked, but I was surprised by how warm it got, even with the bulbs dimmed.  (We run Christmas decorations at 60-70% brightness.)

I split the load between two lamp modules, and they worked fine.  This year out of curiosity, I measured the tree at full brilliance with the Kill A Watt.  I couldn't believe that tree was sucking over 700 watts of power!  Even dimmed to our normal level it was still pulling about 500 watts.  While the tree does produce a fair amount of light from all those tiny bulbs, it produces a tiny fraction of what seven 100W incandescent bulbs would do.  I think it is due to the shunt resistors in the bulbs that keep the string from going out if a filament burns out.

The bottom line is be careful.  These things may pull a lot more power than you expect.

Jeff
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Alan V

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Re: Lamp Module Melt down
« Reply #23 on: December 22, 2009, 06:42:51 PM »

I think it is due to the shunt resistors in the bulbs that keep the string from going out if a filament burns out.

I don't know about your light strings, but most now use a better mechanism when a filament burns out.  There is a wire covered with an extremely this coating of insulation that overlaps a metal post in each bulb.  When a filament burns out, the wire sees the full 120 VAC across it.  That voltage is high enough to arc through the insulation and weld the wire in place, thereby completing the circuit.

It's a very clever cheap way of keeping the strings lit if a filament burns out.  If this happens to too many bulbs in the string, then the remaining bulbs will see a higher voltage and may burn out faster than they would normally.   
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Dan Lawrence

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Re: Lamp Module Melt down
« Reply #24 on: December 25, 2009, 10:53:53 PM »

What's amazing is I have Lamp Modules that I've had since the late 1980's when I was introduced to X10 by a good friend of mine that have been in continuous service for over 20 years without a fault.   :)%
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