Electrical Fire

[JerseyJim]

can you back this up with documentation? the 'high initial surge' of a laser printer is a period of high current draw when the heater comes on. Same as when you press down the lever on your toaster. Completely different thing than the voltage spikes 'surge protectors' are supposed to get rid of.

I had two Brother laser printers fail in very short order. Both were replaced under warranty. After the second incident, Brother's tech service indicated that surge protectors were a problem with laser printers and and tend to shorten their life. They recommended plugging it directly into the outlet which I did. Figured after two quick failures that I had nothing to lose. That was five years ago and the third printer is still going strong.

 

[mrb]

I had two Brother laser printers fail in very short order. Both were replaced under warranty. After the second incident, Brother's tech service indicated that surge protectors were a problem with laser printers and and tend to shorten their life. They recommended plugging it directly into the outlet which I did. Figured after two quick failures that I had nothing to lose. That was five years ago and the third printer is still going strong.

total myth. the issue is with UPS units, many of which output a distorted waveform and/or will shut down on the current surge when the heater turns on. take apart the power supply in a laser printer and you will likely find the same across the line MOVs that are in a surge protector. I own 7 laser printers: 3 hp, 2 color oki, a brother, and a dell and they are all on surge protectors.

 

[PassnThru]

I had two Brother laser printers fail in very short order. Both were replaced under warranty. After the second incident, Brother's tech service indicated that surge protectors were a problem with laser printers and and tend to shorten their life. They recommended plugging it directly into the outlet which I did. Figured after two quick failures that I had nothing to lose. That was five years ago and the third printer is still going strong.

I've got a Brother laser hooked up to a cheap power strip - been like that for about 5 years now and still going strong. The only other thing on the strip is the ink jet printer and I really don't use both of them at the same time so maybe you had an overloaded power strip to being with?
Also, I think it's dangerous to think that just because you pay more for a power strip that it is any better than the 'cheap Chinese junk'. The one that costs more is likely to be just some rebranded 'cheap Chinese junk'. I'm a little confused about one thing - I've seen the Monster brand come up a few times as a supposed quality unit - I've always known Monster anything as the cheap stuff with lots of advertising to justify the price. Did something change?

 

[canuckian]

I had two Brother laser printers fail in very short order. Both were replaced under warranty. After the second incident, Brother's tech service indicated that surge protectors were a problem with laser printers and and tend to shorten their life. They recommended plugging it directly into the outlet which I did. Figured after two quick failures that I had nothing to lose. That was five years ago and the third printer is still going strong.

That's a typical "Brother" response when it's in fact their cheap power supplies that cause the damage. I support a network with 40+networked laser printers (HP and Lexmark) a dozen or so larger Xerox MFP's, too many to count desktop lasers and others that fall into other categories but basically, they're all laser printers. some are plugged into surge strips, some aren't and I've never had many issues either way. I have one older HP (4050 I think) that's been plugged into a surge suppressor for 10+ years and short of replacing toner and installing maintenance kits, it's never failed me.

I use power strips and surge suppressors in my garage but I never leave anything plugged into them and I usually flip their power switches if I'm leaving the garage for more than a couple hours. some call it paranoid, some call it cautious. I just don't want my garage to burn down because of something I could have easily prevented. I also drive my wife nuts by running through the house unplugging appliances and switching off the power bars on the computers before we leave for extended periods of time. That being said, I use the same quality surge suppressors at home as I do at work. The ones at work are always on and always have something running plugged into them (don't really care if that place burns to the ground ) and the only failures I've had were due to age. They just die after a while.

 

[westom]

That being said, I use the same quality surge suppressors at home as I do at work. The ones at work are always on and always have something running plugged into them (don't really care if that place burns to the ground)

Define a difference between the seven dollar protector sold in a grocery store and a $150 Monster? Equivalent circuits. Similar specs. And both do not claim to protect from any typically destructive surge. Monster has a long history of identifying scams. Then selling similar products for even higher prices.

Power strips get recommended when protection is grossly undersized. Then observation *knows* it must be better. An effective protector that earths surges without failure would not be recommended by a majority educated by subjective reasoning, advertising, and observation. A surge that would not harm appliances can destroy a grossly undersized protector's thermal fuse. Observation (by ignoring well proven science) then recommends that protector.

Sometimes its thermal fuse does not trip fast enough. Fire due to cheap or expensive strip protector is too common. Fire by cheap power strips (no protector parts inside) is not.

Printer manufacturers, AT&T, and others strongly recommend no protector type power strips for many reasons. Another reason: a protector too close to an appliance can sometimes make surge damage easier.

Whitneyd88 on 21 Mar 2011 in "My house caught on fire and my tank busted" describes how the protector almost burned down his house:
> A plug caught fire in my room (which was plugged into a surge protecter)
> it was caused by a power surge and caused my tank to burst.

melbourne architect on 20 Apr 2011 in "Safety Switches / Surge Protection" describes others who saw same:
> Cheap surge protectors have been known to catch fire (in one case, a
> Fire Station was burnt out; the red faced fireman later learnt it was
> due to the cheap surge protector/power strip in the office)

Another fire department in Jan 2008 shows what power strips (cheap or expensive) can do when the strip contains MOVs:
http://www.pennsburgfireco.com/fullstory.php?58339

'Quality' power strip protector does not exist. A $4 power strip with some ten cent protector parts will sell for $7 in the Supermarket or for $150 under the Monster label. Read its specifications. Both are electrically equivalent. But naive consumers know the Monster is better only because it costs more money.

Fires and surge damage due to protectors adjacent to appliances is too common.

That printer manufacturer was correct. What he did not say: if you need surge protection, then install products that harmlessly earth that energy. From companies with superior reputations. No strip protector does that protection; especially when grossly undersized to promote more sales. Undersizing (to promote sales and increase profits) is one reason for so many protector fires.

 

[Thruxton]

Define a difference between the seven dollar protector sold in a grocery store and a $150 Monster? Equivalent circuits. Similar specs. And both do not claim to protect from any typically destructive surge. Monster has a long history of identifying scams. Then selling similar products for even higher prices.

That may be true about grocery store products and those of a particular manufacturer, but there are products of better quality. See

http://www.rbs2.com/fire.htm

 

[MBfreak]

I am fairly well versed in electrics and electronics. However I know nothing about the codes that regulate the industry in the US. Anyway , here is my $ 0,02´s worth:
Surge arrestors/ MOV´s must be installed in a fireproof , vented metal housing if installed indoors. They are best placed oudoors at the supply entry if the building is supplied by OH wires. If building is cable fed, the need for surge arrestors is much reduced.
Any home garage/shop need to take into account that you do forget things plugged in. So , a very sensible addition is to supply the shop/garage outlets and lighting over a single contactor that is operated by ONE switch. When you enter light up, when you knock off for the day swith off. Cheap insurance against forgotten stuff.
In Sweden , which like much of the rest of Europe feeds 3phase 380/220 V to most houses it is also customary to refurbish installations with one or several Residual Current Breakers. They are really good protection against electrocution and also against leakage currents that may start fires.

Ola

 

[westom]

In Sweden , ... it is also customary to refurbish installations with one or several Residual Current Breakers. They are really good protection against electrocution and also against leakage currents that may start fires.

The milliamp currents (detected by a RCD or GFCI) does not start fires. An RCD is for human safety; to detect a ground fault. Another type circuit breaker (called AFCI) will detect arcing that might cause house fires. But none of that is relevant here for a few reasons. One is that circuit breakers involve events taking milliseconds, seconds, or even an hour. Protectors are for events that occur in microseconds.

If power strips of better quality exist, then manufacturer specification numbers are posted to define that quality. Power strip protectors do not even claim to protect from typically destructive surges. Must somehow absorb hundred of thousands of joules inside a protector rated only for hundreds of joules.

Properly sized and installed protectors do not absorb surges, are sized to conduct even direct lightning strikes to earth without failure, are located where fire risk is lowest, and actually do effective protection.

A power strip must be sized to safely conduct a current rated by its power cord plug (shape defines that current). And it must have a circuit breaker or some other fuse type device (typically rated at 13 amps or 15 amps). These type power strips are not the fire hazard so often observed with protector type strips, defined by Standler (an industry guru), defined by a North Carolina fire marshal ( http://tinyurl.com/3x73ol ), that caused an apartment building fire in Boston ( http://www3.cw56.com/news/articles/local/BO63312 ), and are why UL1449 was created back in 1987.

Well, even with various UL1449 revisions, these power strip protectors were still creating fires. Meanwhile, why spend so much more money on a power strip that does not even claim to do any effective protection?

First step to averting power strip fires is to install a protector that actually does protection. Earth one 'whole house' protector manufactured by more responsible companies such as ABB, General Electric, Siemens, Square D, Leviton, or Intermatic. A Cutler-Hammer solution sells in Lowes or Home Depot for less than $50. Is rated at least 50,000 amps. And requires a connection to what actually does protection - earth ground.

Better solution means protection for power strip protectors that is also well proven protection for all other household devices. And to use power strips that do not contain protector parts. So that it need not disconnect those protector parts as fast as possible to avert fire.

Either energy is inside the building causing problems including a rare fire. Or energy is absorbed safely outside the building. Only two choices.

 

[MBfreak]

Westom. This is a less than precise comment by you "The milliamp currents (detected by a RCD or GFCI) does not start fires. An RCD is for human safety; to detect a ground fault."
By limiting any possible leakage current to below 30 mA( some 10mA) and tripping on anything above that in less than 50 ms it certainly protects people from electrocution. BUT it also detects leakage currents in the fixed part of the electrical installation. In countries where wiring is run in PVC pipes inside the building frame, a common source of fires is that a large nail is driven thru wooden building beam for some purpose, The nail then goes thru the wood and sticks out on the other side , where a plastic conduit may be nailed before the wall is built. And if the nail penetrates or nicks a phase conductor a leakage current will occur. And this starts fires once in a while. A fixed earth faultdetector in the incomer fuse panel will prevent this .
I am interested in the statement ;Another type circuit breaker (called AFCI) will detect arcing that might cause house fires.This device I would like to learn more about, can you please provide a suitable link, please.

Best regards

Ola

 

[westom]

And if the nail penetrates or nicks a phase conductor a leakage current will occur. And this starts fires once in a while.

For that nail to create a fire, the current must be significantly higher than milliamps. If that nail can cause a fire, then a standard circuit breaker or fuse will blow.

Arc fault breaker detects another type of arcing. Intermittent arcing such as caused by extension cord failures. A problem created wires that move; are not permanently shorted. AFCI were required in all American bedroom circuits starting in 2002. A summary:
http://www.cpsc.gov/cpscpub/pubs/afcifac8.pdf

A worst place to have an arc generated fire or a protector generated fire is in bedrooms. Where more combustible material is nearby and where a fire can most quickly cause death.

These 'better' breakers also provide another feature. Detects another constant type short between neutral and safety ground wires that would otherwise go undetected.

 

[bushpilot]

I dont use power strips in the garage - but they cant be avoided in my office !
NO ONE in our house leaves curling irons or hair dryers plugged in when NOT in use !

I wired PLENTY of outlets in my garage (one every other stud) - on two different circuits - every other outlet on a different circuit - i ran 20 amp wire, and used 15 amp breakers and outlets - OVER BUILT !

 

[westom]

I dont use power strips in the garage - but they cant be avoided in my office !

'Power strips' are not a threat. 'Power strip protectors' have a history and good reason to cause fires. A major difference. Even cheap 'power strips' are sufficient (as long as not daisy chained). But a 'power strip protector' - cheap or expensive - is a fire threat.

 

[MBfreak]

Sorry Westom, but you are not correct.
An istallation that is not protected by a RCB unit has the capacity, as unluck rules , to produce a say 500 mA leakage current thru " that nail" with an arc voltage of 10-50 V. This is certainly enough to start a fire in a dry environment filled with combustible material , such as sawdust, dust or old leaves that has entered the wall interior space. And yes, it happens.
Thanks for the info on the AFCI unit.
Regarding a short between neutral and earth this is detected by any RCB since it creates an unbalance between the phase currents and the neutral current ( ie vectorial addition sum is => trip point of RCB)

Best regards and so long

Ola

 

[westom]

Regarding a short between neutral and earth this is detected by any RCB since it creates an unbalance between the phase currents and the neutral current

The term was carefully selected. 'Better' breakers. The GFCI (RCD) most commonly used (on this side of the pond) will not detect that fault.

Wires inside walls, inside PVC pipe, etc are not encased by combustible material. But an extension cord on a bedroom rug is. Wires in contact with combustible materials are why AFCI were created and required for all bedroom circuits.

Far more dangerous is the power strip protector (not to be confused with other power strips) that has a history of causing house fires.

 

[bjcouche]

As an EE who has bought many surge protector power strips from the big box hardware stores and then taken them apart and analyzed their circuitry, I can safely say that paying more for a unit doesn't guarantee you get better quality, but paying less usually does. All these units use MOV'S (Metal Oxide Varistors) placed from line to line, line to ground and neutral to ground. There have been some newer UL requirements for their design, basically, the newer UL required the MOV's to turn on at a higher voltage to help lessen fire hazards. What this does though is severely limit surge protection. The better units have a thermal fuse wired in series with the main line input and sandwiched between the stack of MOV's. The idea is that if one of the MOV's goes into thermal runaway, the main thermal fuse will open. The cheaper surge protectors usually omit this fuse to reduce cost. Better units go a step further by adding a current limiting fuse in series with the MOV's and sized such that if the MOV shunts a high enough current to be damaged, the fuse blows, taking the MOV out of the circuit. Units with this protection often have LED's indicating "protection is working" because the MOV fuse might be blown but the strip otherwise functions. Even the best units still rely on the MOV and there is always some risk of them causing fires, but good design mostly minimizes the risk.
My personal recommendation is a middle of the road price from a reputable company, but most of all try to get one with a METAL enclosure and not a plastic one. In the event of a catastrophic failure, the metal case is less likely to melt and catch on fire.
Also, plugging the surge protector into a GFCI protected outlet really helps. The surge protector shunts surges from line to ground and neutral to ground. If the surge protector shunts a large enough surge to ground, the GFCI will see this "unbalanced" current and trip preventing the protector from starting a fire. If the surge protector shunts a line to line surge, then the GFCI won't help the situation.
Just my $0.02

Brian

 

[westom]

The better units have a thermal fuse wired in series with the main line input and sandwiched between the stack of MOV's. The idea is that if one of the MOV's goes into thermal runaway, the main thermal fuse will open. The cheaper surge protectors usually omit this fuse to reduce cost.

If any protector does not have that fuse, then it is a guaranteed fire hazard. Some protectors use a thermal fuse. Others have a fuse inside the MOV. Any protector with a UL listing always has a disconnecting device.

Inspection alone is insufficient to define quality. Impedance of its connection to earth is a major and critical parameter.

Protection is always about where energy dissipates. Always. If energy is not absorbed harmlessly outside a building, then no effective protection exists. Therefore effective protectors in every reliable facility first and foremost connect a dedicated earth ground wire as short as practicable to single point earth ground.

No protector - not one - does protection. In every case, either a protector connects hundreds of thousands of joules harmlessly outside to earth. Or the protector is only a profit center. Often undersized (hundreds of joules) protectors fail on trivial surges. During a surge too tiny to harm other appliances. Failure (ie thermal fuse blowing) gets the naive among us to recommend it and buy more.

$7 supermarket protector has a similar thermal disconnect also found in $150 protectors. Both also claim same protection in numeric specs. Without that short and dedicated connection to earth, neither claim effective protection. See its numeric specs that say same. A thermal fuse is important when a protector must make hundreds of thousands of joules just magically disappear. But protection is always about where that energy dissipates. Always.