Questions about Power Strips and Power Distribution Units

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

if you want a workshop strip, get a string of individually switched sockets with an RCD at the end and *maybe* a bypass switch for working on stuff that is "leaking"
just make sure it's illuminated so you know your safety is bypassed!

I don't want a workshop strip. I have a workshop strip. I want to make sure my equipment, when plugged in, doesn't ever have to worry about getting fried when there's a lightning storm.

I now realize PDU is just a word that means power strip in a datacenter. That's all. People use the word as a marketing tool. Some PDUs can have more advanced features than others. Some might have built-in surge protectors, remote monitoring, but PDU is just a word, mostly used in datacenters (from what I've been reading) that just means something that distributes the power to various pieces of equipment. In it's simplest form, a plan old power strip.

I'm thinking perhaps I should try to figure out how much amperage each of my equipment uses, then when I wire the new outlet over in the new house, I can make sure it's equipped to handle everything (even though I'll probably never have everything turned on at once).

The thing I like most about my current strip is how long it is. If surge is something I have to worry about, that'd be the only reason I want to replace it. Well, that and the fact it might not be designed to handle a lot of amperage. I don't know.

[diif]

Re: Questions about Power Strips and Power Distribution Units

No power strips are designed for amperage.
PDUs are designed as you've seen for datacentres where remote monitoring of power or being able to remotely power cycle would be a bonus. They don't really do surge either, that's the job of the UPSs

[stj]

Re: Questions about Power Strips and Power Distribution Units

nothing will save you from a lightning storm unless it's inside the equipment - it will be picked up on the cable between the strip and device.

you need MOV's or GDT's across the mains and any coax inlets.

a lot of the arcade stuff has MOV's across the network connectors.
you dont see that on your pc!!!

[kaboom]

Re: Questions about Power Strips and Power Distribution Units

If a device is designed to accept 120VAC, cutting it down to 110VAC, I can't really see it doing anything at all, really.

Oh yes it will! Consider a constant-power load, like an SMPS or induction motor. Constant-power, OK? Reduce voltage and current goes up. The opposite of what we want; this reduces circuit capacity. Also important, on the POCO side, is that reduced voltage reduces the correcting K/MVARS from capacitor banks. These reduce the effects of partially loaded induction motors (which use more I per W) and heavily-loaded transmission lines. Lower voltage leads to fewer capacitive VARS, leading to still lower voltage (equivalent of long transmission lines' "inductive reactance" in series with current flow)- worst case is "voltage depression" and (?) blackout unless nearby "peakers" are spun up.

It sounds like this power load balancing stuff is just another scam as well.

The only case of legitimate load balancing is in a three phase system, with multiple single-phase loads. For minimum neutral current and mostly-equal phase voltages, we want:

A=10A
B=10A
C=10A
N=~0

rather than
A=10A
B=0A
C=10A
N=10A

In your house with 120/240 single phase, any of this doesn't matter, sicne it's literally (and for good reason) out of reach. The closest you can do is make sure both legs of 120V coming in have approx equal loading- you're still balancing the service, but on each side of the split secondary of the POCO transformer.

The neutral is typically sized smaller than the hots; reduce its current and you reduce "neutral shift" at your service entrance. If you've got a "super neutral" and/or a short secondary run, this is less of a problem.

[kaboom]

Re: Questions about Power Strips and Power Distribution Units

nothing will save you from a lightning storm unless it's inside the equipment - it will be picked up on the cable between the strip and device.

No. That widdle 6 foot power cord ain't acting as a "common mode antenna" while all the other involved conductors do nothing.

Distant termination points of external cables (network, signal, other data) are at different potential than the device in question- step potential forces current thru the two (or more) points. Your machine becomes the "bonding jumper" and induced current happily flows thru it. Stop losing the forest for the trees- such an install needs better bonding.

you need MOV's or GDT's across the mains and any coax inlets.

Stop seeing the AC line and coax individually, get that while seperate "signals," they're interrelated as both have multiple "common points" seperate from each other!

Hence 250.94, 800.100, and 820.100. MOVs aren't going to save anything across each line taken individually. They have to be bonded- all this "put MOVs here because we've always done it this way" just blow equip up. It's a bandaid (at best) and a false sense of safety. Until those seperate services are [b]tied together,[/i] current will flow anytime they're at different potentials- from lightning, cable faults, whatever.

You have a choice- bonding jumpers at the service per NEC, or "substitute jumpers" consisting of your equipment.

a lot of the arcade stuff has MOV's across the network connectors.you dont see that on your pc!!!

Draw an arc from a microwave transfomer to the case of a PC, while it's operating. The PC continues to run, without so much as the CMOS "parasitic junctions" being biased. I've done this, to the amazement of others.

There's a reason that even the old 480V "ungrounded" factory services still required bonding.

[rhomanski]

Re: Questions about Power Strips and Power Distribution Units

15 years ago, a woman in Atlanta was working on her computer when lightning hit in the yard. The newsies reported that the lightning went into a water pipe or something, into the house. Then it transferred into the wiring and went into her computer. Went through the mouse into her hand, came out her toe blowing the tip off and then back into the outlet. I wondered if it could really happen that way. Sounded like a stretch to me, but I'm not an expert.

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

No power strips are designed for amperage.
PDUs are designed as you've seen for datacentres where remote monitoring of power or being able to remotely power cycle would be a bonus. They don't really do surge either, that's the job of the UPSs

So my best bet would be a larger UPS? Where I used to work, they had these two giant boxes and each box held a whole bunch of UPSes. You'd just pull one out, pop a new one in. When the electricity went away, the UPSes would power the entire building long enough for us to get the generator started. Then the generator would power the UPS.

What about those whole home surge protectors that plug directly into the panel? Do you think they're worth the money? Here's a link to one...

http://www.homedepot.com/p/Siemens-F...S140/206560230

It's a 140kA whole home surge protector that plugs directly into the panel. Maybe something like this could help, along with some other protection as well, perhaps?

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

nothing will save you from a lightning storm unless it's inside the equipment - it will be picked up on the cable between the strip and device.

you need MOV's or GDT's across the mains and any coax inlets.

a lot of the arcade stuff has MOV's across the network connectors.
you dont see that on your pc!!!

I'm not following. You're saying there's nothing I can do to protect myself from surges from a lightning storm? I've heard there's not much you can do if it's a direct strike from lightning. If that's true though, how realistic is it for that to happen? I've received a good number of things that were damaged from what I think was surges. I figure maybe the lightning isn't hitting the line but striking close enough or something where it damages it?

One that I always remember in particular....I was young, maybe 18. Someone brought me a PC they were trying to fix for their friend. We had a storm the night before. They had tried everything but couldn't get it to POST. There was a modem inside the PC. I removed the modem, the system POSTed. I figured lightning struck next to the telephone lines. Just enough where it fried the modem. That was maybe 17 years ago. I'm sure things have changed a bit. There's gotta be something I can do to protect my equipment. I'd like the best options, you know? The ones that would give me the absolute best chance of suppressing some surge.

Eventually, we'll save up for a standby generator with an auto transfer switch. When the electricity goes out, the standby generator will automatically kick on and power the house. These can be a bit pricey though. I'm just throwing that out there, because maybe it'll affect what route I should go....

[stj]

Re: Questions about Power Strips and Power Distribution Units

i wouldnt like to see one of those fail.
and mov's do fail - with a bang.

put them in your equipment instead - most psu's already have one.
they cost about 50c in 10's

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

Oh yes it will! Consider a constant-power load, like an SMPS or induction motor. Constant-power, OK? Reduce voltage and current goes up. The opposite of what we want;...

I thought with AC, for the most part, it wouldn't matter. Take my PSU for the PC. I can't tell you if it's a linear power supply or a switch mode power suply. The AC to DC circuitry, whatever it may be, I thought it could handle a variable amount of AC voltage. Not everyone has a steady 120VAC, right? If my power supply was supplied 110VAC, I thought the thing that converted that AC to DC would still be putting out equally as much DC voltage and current as it was before, when it was receiving 120VAC. So I'm wrong with this assumption?

I'm just trying to understand everything. Thanks for helping me try to understand all this jazz. Sometimes, it gets my head a spinning!

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

...
You have a choice- bonding jumpers at the service per NEC, or "substitute jumpers" consisting of your equipment.
...

This right here. Bonding jumpers at the service per NEC....that would help protect me from surges and it'd keep me up to code, right? I'm not very experienced with this Kaboom, so a lot of the words you use I gotta google, to see what they mean. Like POCO. Didn't realize that meant Power Company. Or bonding / bonding jumpers.

So, what I'd want to do is maybe take a bonding jumper and connect it to something like the cable ground at the switch and the grounding bar or the neutral bar on my panel? Or maybe directly where the cable comes into? Because we will have a cable modem, the telephone would go through the modem. That shouldn't be an issue, right? We wouldn't need to somehow tie the ground into that telephone line, because the cable modem is already grounded...

Would this completely prevent me from my equipment getting damaged during a surge? Having it properly bonded and everything?

Draw an arc from a microwave transfomer to the case of a PC, while it's operating. The PC continues to run, without so much as the CMOS "parasitic junctions" being biased. I've done this, to the amazement of others.

Because they're bonded, right? How do I draw an arc from the microwave transformer? I want to try this. Instead of the case, what about something like where the telephone line plugs into the modem in the PC? It'd have the same effect, because the modem is sharing the ground of the case, which is sharing the ground that goes into the power supply...right?

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

15 years ago, a woman in Atlanta was working on her computer when lightning hit in the yard. The newsies reported that the lightning went into a water pipe or something, into the house. Then it transferred into the wiring and went into her computer. Went through the mouse into her hand, came out her toe blowing the tip off and then back into the outlet. I wondered if it could really happen that way. Sounded like a stretch to me, but I'm not an expert.

Our friend Rena claims she's been hit by lightning 4 or so times now. We believe that is a stretch as well. I did see a guy on a video get hit twice in a row though. It didn't look fake. It left this giant black spot on the ground where he was standing. It knocked him out and when he got up, he looked really dazed. He started walking and bam, it happened again, like 20 seconds from the first time. He got up and this time he ran. Both times, black spots on the ground.


Our old social studies teacher in High School, Mr. Bush, he told us a story of when he was younger. There was a child who got his fingers between the two prongs on a plug that plug into the wall. The kid was messing around or something and tried plugging it into the wall. Mr. Bush said the tip of his finger actually exploded and he said he'd never ever forget that, as long as he lived.

[stj]

Re: Questions about Power Strips and Power Distribution Units

our metalwork teacher didnt have any fingertips on one hand.

makes you wonder how these people actually qualified to teach others!!!

[kaboom]

Re: Questions about Power Strips and Power Distribution Units

Because they're bonded, right?

No, because the computer case "bypasses" the current around the internal parts.

How do I draw an arc from the microwave transformer? I want to try this.

Sorry, not giving details out. If you ask something like this, you're better off not playing around. Those MOTs are not to be taken lightly! The only "common" thing most people can relate to that's as (or more) dangerous are the primary AC lines on the crossarms/top of the poles.

Instead of the case, what about something like where the telephone line plugs into the modem in the PC?

That'll blow the front end of the modem out, and eventually find a path to the chassis. As it arcs around the modem PCB, any carbon tracks that bridge to the PCI connector will dump this current into the motherboard. It shouldn't be hard to figure out what'll happen.

It'd have the same effect, because the modem is sharing the ground of the case, which is sharing the ground that goes into the power supply...right?

The bracket and ground plane on the modem PCB share the chassis ground, but the balanced lines of the POTS jack do not! Hence telco protectors having two shunt paths; one from each wire of the pair to your elec svc ground/bond. Both sides of a POTS line are considered floating.

Along that line, don't be tempted to jump an arc (which you won't be, right?) to the common of any audio jack- too little conductor area and close proximity to signal traces will lead to coupling into the onboard audio IC(s). USB? Forget it. While the shield may be heavy enough, most cheep cases do not tie the shield in properly- actually, they leave it floating! Not bonded at all. This was a big part of why the ICH5 was prone to blowing up. Static would come in on the USB lines, because the unbonded shield wasn't shunting this to the chassis; then, the CMOS parasitic junctions got biased by the discharge. That entire part of the chip essentially became a low-ampacity SCR that attempted to short out its +5V supply. Keep in mind, the static itself had too little energy to destroy the device; it merely biased the "gate" of the "SCR," since they left out the usual CMOS input protection diodes. Intel was concerned about those diodes' junction capacitance slowing down the USB, and/or was cheep, possibly both. Again, the static only "triggered" this parasitic SCR, which then drew extreme current from the system's power supply. Either the bonding wires inside the chip (not related to the NEC) burned clear, "isolating" the USB section from the rest of the system, or they held on and the entire chip burned up.

[Spork Schivago]

Re: Questions about Power Strips and Power Distribution Units

...Sorry, not giving details out. If you ask something like this, you're better off not playing around. Those MOTs are not to be taken lightly! The only "common" thing most people can relate to that's as (or more) dangerous are the primary AC lines on the crossarms/top of the poles.

I don't know what I was thinking! I wouldn't take apart a microwave anyway. I'd probably end up killing myself!!!

That'll blow the front end of the modem out, and eventually find a path to the chassis. As it arcs around the modem PCB, any carbon tracks that bridge to the PCI connector will dump this current into the motherboard. It shouldn't be hard to figure out what'll happen.

So how come this doesn't happen when you put an arc on the case? The modem faceplace is grounded to the computer chassis. The modem uses that ground, right?

The bracket and ground plane on the modem PCB share the chassis ground, but the balanced lines of the POTS jack do not! Hence telco protectors having two shunt paths; one from each wire of the pair to your elec svc ground/bond. Both sides of a POTS line are considered floating.

Oh! That answers my question.

Along that line, don't be tempted to jump an arc (which you won't be, right?) to the common of any audio jack...

No, I won't be tempted to. I gotta take a break from things. There's some really wrong with my head and the docs are trying to figure it out. I don't notice it so much but people around me have, to the point where some of them have actually contacted the doctor and now the doctor wants my wife to go in and discuss treatment. One of the treatment plan involves going up to Buffalo long term, for a very long time. With a baby coming, I think that'd be a horrible idea! But the doc told me she thinks with my daughter on the way, that's even more reason as to why I should go. Now, they want to talk to Jess, my wife. I think they feel I don't understand what they're saying, and at this point, that's a very real possibility. At first, things at night started getting a little weird, now during the day, things are getting a little weird.

It seems like it's harder and harder to remember stuff and I'm really foggy sometimes now. The other day, some total stranger came up to me and started talking to me, asking how I was doing. I was polite but I never say the guy before in my entire life. Once he left, my wife claimed he was my long time friend. Sometimes, I think she's messing with me, trying to make me feel like I'm crazy, then other times, I think maybe I really am crazy.

Either way, I think it's time to not play with electricity right now.