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It’s That Time Of Year Again

Many people when they need more outlets grab a power strip.  They don’t really consider what the load is they’re running off the strip as a whole.  Many will do the worst thing in the world and cascade power strips for more outlets, or plug a very large current item into the power strip.  There’s a couple things going on that make ignoring these factors a bad idea.  The biggest is that this is the result.

An early Saturday morning fire destroyed a house on Lea Hill. The family escaped uninjured. - Courtesy photo/Mountain View Fire & Rescue

The cause:

According to fire investigators, a power strip started the fire, which caused an estimated $250,000 in damage. Multiple computers and a space heater had been plugged into the strip, but what role that played remains uncertain.

I’m going to explain now exactly why cascading power strips, and ignoring load concerns is a bad idea and results in the above.  First read this article on an introduction on basic electronics.  In doing this I’m also going to explain why you never replace a circuit breaker or fuse with anything but a matching value.

Power Losses A Quick Reminder:

Did you see the section involving wire diameter, length, and overall resistance?  There’s a minimum wire gauge for carrying different loads of current.  The reason being is power losses over the wire.  Remember the equation, I2R.  This can be used to determine power lost over the wire is dissipated in the form of heat.  Lets start off with a simple example.

A Base Load Example:

Residential building codes state that for a 12 gauge wire the maximum current load is 20 amp breaker.  We have a computer using a 650W power supply and two LCD displays (~75W). These three are plugged into a single 14 gauge surge protector plugged into an outlet on the 20 amp circuit.  Now while that 650W supply may not be operation at full load, we will assume it is for calculation purposes.

Circuit breakers are rated to carry 80% of their rated nominal load continuously.  This means that our breaker can supply 16 amps continuously to our load distribution the power strip.  This works out to be 1760W = (20*0.8)A*110V that the circuit can supply.  Though the surge protector can only safely deliver 1320W = (15*0.8)A*110V due to it only having 14AWG wiring.  Most power strips will have a safety breaker that will enforce this limit, however they can fail and on cheap strips they may not even work.  Currently our load is only 800W so we are well within the safe range.

How Easy It is To Cross the Threshold:

Now lets say we want to add a space heater since the wife is cold.  If we add the 800W oil heater to out power strip with our computer.  This moves the load on the power strip up to 1600W.  This is beyond the 14 AWG capacity of 1320W.  This will cause the temperature of the wires to go beyond their rated values.  This can be a serious problem if the power strip is located in an area where heat cannot dissipate.  The addition of the power strip also adds extra length increasing your overall I2R losses.  This is why you don’t want to put a large load such as a heater on an extension cord.  If you do, make sure it is a heavy grade extension cord.  The safest method is to plug it directly into a wall outlet.  This will still be below the 20A continuous rating, prevents the extra I2R loss from the extra length, and doesn’t overload the the smaller power strip.

So What About Cascading Them:

Now so far we’ve only been really talking about a single power strip, what happens when you cascade them?  This is where another lesser known problem rears it’s head.  The majority of heating in house hold power distribution circuits are at junctions.  Where wires are tied together, plugs and outlets, and screw terminals.  This is because the resistance in the joint higher than the surrounding materials.  Again, I2R comes in to play with the larger resistance at the joint.  That power goes somewhere and it is released as more heat into the system.  So adding extra power strips increases the resistance in the line and increases the overall power losses.

So What About Circuit Breakers:

Now how does that apply to circuit breakers though.  Say instead of a 12 AWG circuit with a 20A breaker it’s a 14 AWG circuit with a 15A breaker.  It keeps tripping and you think it’s faulty.  All you have in your chest to replace it is a 20A breaker.  You have now allowed a much larger current to flow across the circuit that it is safely rated for.  You have upped the trip limit from 12A to 16A, thus your I2R loss is going to increase.  That increase of 4 amps increases the power dissipation required of the wire by 1.7x.  Again that power is dissipated in the form of heat, in your walls, that retain heat, some packed with insulation.  You have turned your house wiring into a toaster element, not a good idea.

Final Overview:

So there’s a rough idea of 

  1. Why you don’t cascade power strips.
  2. Why you plug high power appliances into the wall, or use a large gauge extension cord with a single outlet.
  3. Why you don’t swap a smaller breaker for a larger one.
  4. The physics behind what cause the fire above.
So please, don’t cascade power strips, don’t swap breakers, and think about your loading if your strips getting full.  It’s simple and easy.  As always if you have questions feel free to ask.  
*Sometimes I feel like a doctor with the burden of knowledge when it comes to electronics now.  Growing up I wouldn’t have hesitated to cascade power strips, now I avoid it at all costs.

Quote of the Day – Tam (12/10/11)

Crazy Guy With Gun: If you don’t have your own pistol, you may have to wait the rest of your life for the police to bring theirs.

Tam – Tab Clearing…


[In the words of PDB, carry your damn guns people.  To steel from Breda, it’s a lighter burden than regret.  It’s like a trauma kit, it does you absolutely 0 good if it’s not with you when you need it.  You’re still bleeding out while waiting for someone else to arrive with theirs. -B]

SSCC #206 – Minneapolis

In the third-largest settlement for a police incident in the past two decades, the city of Minneapolis on Friday approved a $1 million payment to a mother of two who was severely burned when officers, acting on a tip looking for drugs they never found, used a flash/sound device, commonly known as a flash grenade, during a raid on a south Minneapolis apartment.

The injury thought isn’t even the best part.

City spokesman Matt Laible told 5 EYEWITNESS NEWS, “The application correctly set out the grounds for a no knock warrant. The warrant itself did not include the “no knock” provision due to an inadvertent error.”

So lets make this clear.  Cops execute a warrant that was issued with an “announcement of authority” clause as a no-knock.  Then they find absolutely no drugs in the residence or evidence there of, and they injure someone not even associated with the investigation.  Good news for the cops though:

No police officer involved in the raid has been disciplined for the incident, the city confirmed.

Every officer violated the terms of the warrant and they carry the responsibility of it.

State Sponsored Criminal Count 206: Minneapolis PD

Because who needs to knock when you can lob flash grenades at people injuring them and get away with it.

In Which Ladd Shows He’s a Sniveling Coward

Earlier this week I wrote a post on how I know I’m doing a good job.  Well Ladd to make sure his responses were harder to notice updated his article.  As always he twists words and moves things out of context.

On his blog, TMM added that those who participated in the vigils “are faster on the draw than a personal injury lawyer to dance in blood.”

What I actually said was:

This coming from a group [CSGV] of individuals who circle around like vultures and are faster on the draw than a personal injury lawyer to dance in blood.  When ever there is a shooting the gun grabbers waste no time to attempt to levy the situation for their political gain.  See Virginia Tech and the recent Mount Rainier shooting for examples.  They do not care about the people, they care about their political ends.  Don’t believe me, look at the blood dancing they did in Tuscon while the family that lost their daughter was saying the exact opposite.

That comments was also a direct response to Ladd saying my comments were inappropriate, I added the italics to help illustrate who the subject was from the previous sentence.  I never said anything about people participating in the vigils dancing in blood.  I am saying that those doing it for political means as a heart string are dancing in blood.  The organizations who organized it and are upset that the gun community expanded the effort to include all victims of violence.  Not just the fixed metric of gun violence.

What I find most telling though is that there are no comments allowed on the CSGV blog website.  Updates like the above are hidden and not mentioned.  Basically the only way to discover changes like that is to reread the entire article.  It’s his site, he can do whatever he wants.  I would point out though that I have open comments, the only thing I delete is spam, personal threats, and things that just are noy acceptable in decent society.  I’m more than willing to argue, I even have open comments and user ratings on my video.  Lets look at those stats shall we?image

Lets look at the most popular video for Too Many Victims from the opposite view point.

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Oh snap, note the Brady video was shown on Calguns.  So now comes the question, how many of those views were from the pro-rights side of this debate.  No option for likes or dislikes so it’s hard to tell how many people liked this video.

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Well, this one was linked by the HuffPost and still only got 1204 views.  Even if you combine the two Brady videos, which have been out for a total of 5 weeks between the two, we got 3 times as many hits in 5 days.

The fact is the Brady Campaign and the CSGV are blood dancers.  They capitalize on the suffering of others to promote their political agenda.  When someone dies, they will use it to promote their agenda no matter what.  Even if it means defending an armed robber.  They will blame changes in legislation that would have had no effect on the incident.  They want to exclude victims of non-gun violence because it doesn’t further their agenda.  They then attack us because our stated goal is to make fewer victims.  Our goal is to arm people with the tools and knowledge to not be a victim.  They are upset with that because with fewer victims there is less blood for them to dance in.