Electrical Wiring Headaches Rant

[jaygeel93]

Today I was replacing my parent's old tv w/ some 27" Westinghouse lcd because of the DTV transition. While i was trying to find the power outlet, my dad pointed me to the 3 power strips daisy chained together all plugged into one outlet. Ok the apartment i live in was built somewhere in the 60's, and 3 power strips chained together in this apartment w/ all the outlets occupied is a horrible sight. He told me is was for "safety" reasons. His philosophy is that the more outlets you have plugged in together is that you then have more available current for each one. uhhh ok...

and just another short story.
I was plugging in the tv at my school to watch some boring history video or something, this was years ago. And my teacher had a bunch of knots tied into the 50' or something extension cable. I began to take them out when she yelled at me because she told me that tying a knot into power cable is a form of surge protection.

ok i'm done. i just wanted to get my feelings out.
if you have any ideas on what i should say to my teacher or dad, please feel free to comment below.

[tehboris]

Health and safety will tell you not to plug power strips in to power strips. The technical reason not to do it is becasue of the maximum amperage the strip is rated at. In the UK they are most (if not all) rated at 13A. If the current flowing though the first strip exceeds 13A in theory the fuse should blow, but if it doesn't then you have a fire hazard. Current over 13A = wires get warm = plastic melts = plastic catches on fire = house burns down.

If you add up the maximum current of all devices been turned on and it comes close to or exceeds the amperage rating on the first power strip in the series (assuming they are all rated equally) then you need more wall sockets.

[trunolimit]

Health and safety will tell you not to plug power strips in to power strips. The technical reason not to do it is becasue of the maximum amperage the strip is rated at. In the UK they are most (if not all) rated at 13A. If the current flowing though the first strip exceeds 13A in theory the fuse should blow, but if it doesn't then you have a fire hazard. Current over 13A = wires get warm = plastic melts = plastic catches on fire = house burns down.

If you add up the maximum current of all devices been turned on and it comes close to or exceeds the amperage rating on the first power strip in the series (assuming they are all rated equally) then you need more wall sockets.

yeah what he said.

when I was working as an electrician in vegas it was code that every wall had to have an outlet, or was it every six feet? excluding walls with windows. anything out side had to be on a GFI and anything within 4 feet of water (sinks and faucets) had to be under a GFI. power strips are a fire hazard.

knots in a cable is just bad because it might split the wires internally. I know it's hard to do with power cables but it's very easy when you have knots in data cables like cat5 or optical fiber (especially optical fiber). I know twisting opposite poled wires helps reduce heat generated by electricity and reduces cross talk.

[revision3fan]

Has the apartment wiring been upgraded to 3-wire (a connection to earth ground wire)?

If not, is there a ground fault circuit interrupter for the outlet?

Curious.

[guytheninja]

Ok the apartment i live in was built somewhere in the 60's, and 3 power strips chained together in this apartment w/ all the outlets occupied is a horrible sight. He told me is was for "safety" reasons. His philosophy is that the more outlets you have plugged in together is that you then have more available current for each one. uhhh ok...


If I understand you correctly, you dad is just dead wrong. What I think he is doing is the following:

|outlet|---->|Surge1|--->|Surge2|--->|Surge3|

And he is plugging in devices into every available socket. Well that's just dangerous. Lets say that S3 has 6 available sockets, S2 has 5, and S1 also has 5. If he is connecting 16 devices. Then the outlet and Surge1 will see the cumulative current for all 16 devices. If this current is above the rating for the surge protector, you will either have a fire, a breaker will trip, fuse will blow, or (as has happened to me) your outlet could fry.

Its like a tree, all the nutrients from the roots go through the trunk right.

Remember P=VI or Power = Voltage*Amperage
http://en.wikipedia.org/wiki/Electric_power
---> your volts are set by the power company to 120 Vrms, in order to increase power, you have to increase the amperage. Doesn't it make sense that if you have too much power going through an outlet, you could have a fire?

Interesting side-note:

|outlet|---->|Surge1|--->|Surge2|--->|Surge3|

If your dad was still using this series surge protector connection scheme and hooked everything into the third surge protector and did not hook anything into the five available ports on S1 and S2, this would be fine. Why? Well because each surge protector would see the same amount of current flowing through it. If the current didn't exceed Surge3's ratings, Surge2 and Surge1 should be just fine (I've seen this type of connection scheme used many times when students had to present their final project, and they needed power at their booth).

However, in general, its not a good idea to hook surge-protectors together. Just use an extension cord (that's what they are for).




and just another short story.
I was plugging in the tv at my school to watch some boring history video or something, this was years ago. And my teacher had a bunch of knots tied into the 50' or something extension cable. I began to take them out when she yelled at me because she told me that tying a knot into power cable is a form of surge protection.


Well, I'm not convinced that a knot in a cord is a good or even remotely decent surge protector. I'll tell you what my thoughts are:

A single knot in a cord is actually a 1 turn inductor with an air core.
http://en.wikipedia.org/wiki/Inductor

Now inductors are useful for regulating current flow. They have the following equation:

V=L*(di/dt) Where V is the inductor voltage, L is the inductance value (in Henry's) and di/dt is the change in current over change in time for the current going through the inductor.

Inductors hate changes in current. They will use the V in that equation to either boost the current (if it goes too low) or limit the current (if it goes too high). Now if you have a gigantic inductor with an L of 1 Henry and you try to suddenly change the current, you will hit a brick wall, but if you suddenly change the current on a wimpy 1 pico-Henry inductor, it will be like running through a wet paper towel.

I think that loop in the wire is like a 1 pico-Henry inductor. Just try out this website on calculating inductance. A "1 turn" inductor just sucks not matter whats going on.
http://www.66pacific.com/calculators/coil_calc.aspx

Even if the one-turn inductor did an excellent job of limiting the current ----> what is going to limit the 1 million or so volts from the lightning strike!?

Check out this website about how surge-protectors work:
http://www.pcmag.com/encyclopedia_term/0,2542,t=surge+suppression&i=52279,00.asp

Series mode surge protectors basically "take the hit". They slow down the surge both in terms of current AND voltage. And they are designed by engineers to do so safely.

As you can see, the Series mode Surge Protector has the following schematic:

|Outlet| ---> |Large Inductor 1| ---> |Large Capacitor Bank| ---> |Inductor 2|

1. Large Inductor 1 reduces the amount of current coming in.
2. Large Cap Bank reduces the voltage of said current.

I=C*(dv/dt) for capacitors. Capacitors hate sudden changes in VOLTAGE.

3. Inductor 2 reduces the current once again.


Anyway, I hope I helped you (or hilariously confused you). Either one will be fine by me. :)

[dark_shroud]

@jaygeel93, in situations like this I find it best to just buy them something like this. http://www.newegg.com/Product/Product.aspx?Item=N82E16812220010

My still living grandmother isn't bad. And lucky for me both my parents have worked with electronics professionally. My sisters are a different story.

Six years ago I helped my sister buy a new TV, VCR, & DVD player after her building had a fire and some of her components were destroyed by water damage. Anyway I found she had one power strip (non surge protector) plugged into a second power strip with an extension cord running in to the second. The extension cord was running to the surge protecter we gave her years earlier and was powering her PC, Monitor, & Printer. So I had her buy a surge protector strip to handle her TV, & all her boxes. I than ran a 15amp extension cord under a guard along the wall from one wall with an un-used outlet to her entertainment center. There were no other items plugged in on that wall so the whole 15amp breaker was just running the TV, set top boxes, & game systems. So the 15amp outlet that was powering everything was now only running the PC. The PC seemed to even run better after that.