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  # 1001753 9-Mar-2014 15:56
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gregmcc:
A voltage spike is NOT a current spike, two different things, if the voltage is dropping when the current increases then there is a wiring problem.


I never said it was the same thing? I said that a surge when power is restored is not a voltage surge so wont cause damage.

And no there is no wiring problem when the voltage drops on a massive inrush current, its just ohms law and 400+ amps of inrush due to the large number of SMPS and electronically ballasted lamps with totally empty filter caps to fill and minimal power factor correction inductors because they are small loads so dont have to have them fitted.

gregmcc:
Again the switch in the meter box is exactly that, a switch, if 'They' have required you to fit a circuit breaker in there as well the reason is more than likely the pole fuses are under rated for your load, looks like the power company got you to fix their problem at your cost


At the time the pole down the driveway was flagged as "do not climb" and to upgrade the supply from the pathetic 63A one that the people that built the place had put in we would have had to pay to replace the pole at a massive expense. They basically said pay for the next call out for the pole fuse or get a breaker put in so that you can reset it. The 6kw spa pool is gone now and I am down to 3 people in the house so there isnt 4 fan heaters running at the same time over winter anymore so its not an issue. The pole has been replaced for whatever reason at no cost to anyone down the drive way so I can go to 3 phase here if the need arises in the future but I don't foresee that happening.

gregmcc:
richms:
The increase in voltage is slower after an external power outage as everyones houses are full of loads that are pulling their inrush surge, so there is a massive voltage drop in the system.

again not correct, there are many rules and regulations to ensure that this should not happen, correct cable sizing for connected loads etc, maximum demand calculations.


The regs have heaps of room for non steady state voltages. A second or so of under voltage is not of any concern to any gear, and most stuff gets tested on a supply that is ramped up even slower than a supply being livened up. Maximum demand calculations is based on steady state currents not the inrush of every single house coming back on line at the same time.

You have a massive amount of capacitance in all the appliances in the house, and that voltage cant go from 0 to 380 instantaneously. Ramp up and inrush is normal and allowed for. Its just when you are a geek with a hell of a lot of stuff the standard breakers tend to trip a little too easily.




Richard rich.ms

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  # 1001754 9-Mar-2014 16:04
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im in christchurch, when our power has gone out due to earthquakes and come back on hours or days later we never bothered turning the circuit breakers off, everything turned back on at once and nothing ever blew up.

i do have surge protectors on everything in my room though, computer, heater, modem, switch, nas etc.

but at the time this was an adsl modem.





 
 
 
 


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  # 1001909 9-Mar-2014 21:43
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gregmcc:
ubergeeknz: Power cuts are often followed by a voltage spike.  These can kill electronic equipment.  If we have a power cut at home I usually leave one light on (flourescent) so that I know when it's returned, and switch off all the power socket breakers.



I've heard some stories before, but this takes the cake, do you have any recent examples of these voltage spikes after a power cut?



Happens alot in rural hawkes bay. We have customers that have their 42" plasma tv's and routers on a UPS because they get voltage spikes after a power cut. Well i am not sure if its a voltage spike, but whatever it is, usually its as power is restored they tell me.




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  # 1002055 10-Mar-2014 11:32
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Just a week ago Johnsonville area had a power cut the ONT went off and it came back when the power was restored.  Well .. considering the avg Joe they won't things off during the power cut .. and some may be out when they get a power cut and then restored. 

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  # 1002253 10-Mar-2014 18:21
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jacwlg: 
Anyone can give some sort of scientific explanation to this?

Sure ... the less you know the more you have to make up!  :)
As though anyone is going to bother switching it off, especially when it's someone else's hardware.

No doubt the nature of switch-mode power supplies will deal with all sorts of crap on the line and it's likely to be well-speced regarding DC voltage output regulation.

I would be more worried about the possibility of eventual melt-down, it being a plastic-housed power pack made by the lowest bidder and left on 24/7 for a decade.  I really wish they had included the PS in a metal box inside the ONT like other other professional hardware.

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  # 1002439 10-Mar-2014 21:50

Im actually happy that the Chorus ONTs have a separate power supply. Since it makes it easy for me to build a 12V UPS to run the ONT, Router, WIFi AP, and my old 8 port 100BaseT switch. As well as some other 12V circuits that need battery backed power. Gutted I didn't think to check how my 24 port Gigabit switch was powered before I bought it - it plugs directly into mains.


It would also make it easier for Chorus to maintain all the ONTs. If a power surge happens, the worst case is it would fry the wall wart supply while the ONT will be fine. The Chorus service Techs will keep a box of new supplies in their vans, and just swap them out. A small wall wart supply would be far cheaper than an ONT.


Also imagine the fun to be had if the ONTs were in metal cases. Something would go wrong somewhere that would cause the case of one to become live. And then there will be a news article "child killed after touching live Chorus ONT"

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  # 1002453 10-Mar-2014 22:26
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Aredwood:Also imagine the fun to be had if the ONTs were in metal cases. Something would go wrong somewhere that would cause the case of one to become live. And then there will be a news article "child killed after touching live Chorus ONT"

That's a ridiculous scenario.  Homes already have numerous metal appliances connected to mains.

 
 
 
 


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  # 1002605 11-Mar-2014 09:55
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raytaylor:
gregmcc:
ubergeeknz: Power cuts are often followed by a voltage spike.  These can kill electronic equipment.  If we have a power cut at home I usually leave one light on (flourescent) so that I know when it's returned, and switch off all the power socket breakers.



I've heard some stories before, but this takes the cake, do you have any recent examples of these voltage spikes after a power cut?



Happens alot in rural hawkes bay. We have customers that have their 42" plasma tv's and routers on a UPS because they get voltage spikes after a power cut. Well i am not sure if its a voltage spike, but whatever it is, usually its as power is restored they tell me.


In term it's call brownout, I have most my electronics on UPS because of it and it's not just after a power cut even with power it's on we still gets it here in Christchurch.



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  # 1002674 11-Mar-2014 11:12
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D1NZ:
raytaylor:
gregmcc:
ubergeeknz: Power cuts are often followed by a voltage spike.  These can kill electronic equipment.  If we have a power cut at home I usually leave one light on (flourescent) so that I know when it's returned, and switch off all the power socket breakers.



I've heard some stories before, but this takes the cake, do you have any recent examples of these voltage spikes after a power cut?



Happens alot in rural hawkes bay. We have customers that have their 42" plasma tv's and routers on a UPS because they get voltage spikes after a power cut. Well i am not sure if its a voltage spike, but whatever it is, usually its as power is restored they tell me.


In term it's call brownout, I have most my electronics on UPS because of it and it's not just after a power cut even with power it's on we still gets it here in Christchurch.




ive never noticed anything dying, how do you tell, do you have a meter plugged in that notifies you of voltage spikes? what area are you in? i'm on the marshland road/QEII dr power thingy





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  # 1002788 11-Mar-2014 13:54
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hamish225:
D1NZ:
raytaylor:
gregmcc:
ubergeeknz: Power cuts are often followed by a voltage spike.  These can kill electronic equipment.  If we have a power cut at home I usually leave one light on (flourescent) so that I know when it's returned, and switch off all the power socket breakers.



I've heard some stories before, but this takes the cake, do you have any recent examples of these voltage spikes after a power cut?



Happens alot in rural hawkes bay. We have customers that have their 42" plasma tv's and routers on a UPS because they get voltage spikes after a power cut. Well i am not sure if its a voltage spike, but whatever it is, usually its as power is restored they tell me.


In term it's call brownout, I have most my electronics on UPS because of it and it's not just after a power cut even with power it's on we still gets it here in Christchurch.




ive never noticed anything dying, how do you tell, do you have a meter plugged in that notifies you of voltage spikes? what area are you in? i'm on the marshland road/QEII dr power thingy


In short term you prolly wont notice anything, but it does killing electronics slowly, some insurance company already started accepting claim for electronics killed by brownout.
And I don't have to have a meter plugged in to know because lights in the house would go dim for half second or so and sometime even longer also my UPS would kick in like crazy during that time.

I am around Lincoln University area.

This is getting abit off topic, but I would think ONT blowing up it's kinda over the top, lol.

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  # 1002799 11-Mar-2014 14:12
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D1NZ:
hamish225:
D1NZ:
raytaylor:
gregmcc:
ubergeeknz: Power cuts are often followed by a voltage spike.  These can kill electronic equipment.  If we have a power cut at home I usually leave one light on (flourescent) so that I know when it's returned, and switch off all the power socket breakers.



I've heard some stories before, but this takes the cake, do you have any recent examples of these voltage spikes after a power cut?



Happens alot in rural hawkes bay. We have customers that have their 42" plasma tv's and routers on a UPS because they get voltage spikes after a power cut. Well i am not sure if its a voltage spike, but whatever it is, usually its as power is restored they tell me.


In term it's call brownout, I have most my electronics on UPS because of it and it's not just after a power cut even with power it's on we still gets it here in Christchurch.




ive never noticed anything dying, how do you tell, do you have a meter plugged in that notifies you of voltage spikes? what area are you in? i'm on the marshland road/QEII dr power thingy


In short term you prolly wont notice anything, but it does killing electronics slowly, some insurance company already started accepting claim for electronics killed by brownout.
And I don't have to have a meter plugged in to know because lights in the house would go dim for half second or so and sometime even longer also my UPS would kick in like crazy during that time.

I am around Lincoln University area.

This is getting abit off topic, but I would think ONT blowing up it's kinda over the top, lol.


oh, my lights do that whenever our heat pump kicks in, they've always done it since i can remember, but they do it now even when the heat pump isnt on. so i guess thats what you're talking about.





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  # 1002825 11-Mar-2014 14:55
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hamish225:
D1NZ:
hamish225:
D1NZ:
raytaylor:
gregmcc:
ubergeeknz: Power cuts are often followed by a voltage spike.  These can kill electronic equipment.  If we have a power cut at home I usually leave one light on (flourescent) so that I know when it's returned, and switch off all the power socket breakers.



I've heard some stories before, but this takes the cake, do you have any recent examples of these voltage spikes after a power cut?



Happens alot in rural hawkes bay. We have customers that have their 42" plasma tv's and routers on a UPS because they get voltage spikes after a power cut. Well i am not sure if its a voltage spike, but whatever it is, usually its as power is restored they tell me.


In term it's call brownout, I have most my electronics on UPS because of it and it's not just after a power cut even with power it's on we still gets it here in Christchurch.




ive never noticed anything dying, how do you tell, do you have a meter plugged in that notifies you of voltage spikes? what area are you in? i'm on the marshland road/QEII dr power thingy


In short term you prolly wont notice anything, but it does killing electronics slowly, some insurance company already started accepting claim for electronics killed by brownout.
And I don't have to have a meter plugged in to know because lights in the house would go dim for half second or so and sometime even longer also my UPS would kick in like crazy during that time.

I am around Lincoln University area.

This is getting abit off topic, but I would think ONT blowing up it's kinda over the top, lol.


oh, my lights do that whenever our heat pump kicks in, they've always done it since i can remember, but they do it now even when the heat pump isnt on. so i guess thats what you're talking about.


Yes, it basically means unstable or spikey in voltage, in the case of brownout voltage dipping to like 180V.

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  # 1003088 11-Mar-2014 23:47

KiwiME:
Aredwood:Also imagine the fun to be had if the ONTs were in metal cases. Something would go wrong somewhere that would cause the case of one to become live. And then there will be a news article "child killed after touching live Chorus ONT"

That's a ridiculous scenario.  Homes already have numerous metal appliances connected to mains.




It is one of those things that is highly unlikely to happen, but not impossible if it had a metal case. Possible options:

Class 1 appliance - exposed metal parts which are connected to earth via a plug with an earth pin.
*Fault within appliance causing case to become live and earth broken / not connected in power point / extension cord.
*Broken / disconected earth in power point/ extension cord/ cable in wall. Capacitive coupling between earth and phase causes enough voltage to form on case to give a tingle / shock. Even though appliance is otherwise ok.
*Fault on Neutral wire to house or swapped phase / neutral upstream of main switch board. Either of these faults can cause everything that is earthed to instead become live.


Class 2 appliance (double insulated appliance).
*House has been built with that gib board that has the silver foil on the back. A fault elsewhere causes that foil to become live. (screw through a wire being 1 option) The screws that hold the ONT to the wall allow the ONTs case to become live also.
*A fault in something that is connected to the ONT via 1 of it's data cables causes dangerous voltages to get transferred through the cable to the metal case.

Alot of these things can happen to metal cased appliances even if there isn't any fault with the appliance itself. The faulty extension cable one has happened to me personally. I got a shock off a metal cased battery charger that I was using outside. Measured 95V from the case to ground. Turned out that the earth wire in the plug end of the extension cord had come loose allowing the case of the battery charger to start "floating" in relation to ground. There wouldn't have been enough current to kill me but it was enough to scare me.


Considering how many ONTs are being installed It is likely that someone could get unlucky, if they had metal cases. And I can't see how an ONT with a metal case would be better from a reliability or operational point of view.

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  # 1003090 11-Mar-2014 23:51
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Solution is the chorus tech plugs in an outlet tester and checks it as part of the install process.

Has anyone had any concern about sky boxes they are metal and there are more of them than there will be onts in nz so if metal cased items that people use were an issue they would have shown already.




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  # 1004651 13-Mar-2014 03:26
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If power is out for two hours, then it will probably be out many hours more. An ONT should have a UPS that provides maybe four hours of power. Best is to power it off so that UPS power is available should emergency communications be necessary.

Besides, running a UPS down to zero power is bad for its battery.

The word "surge" has numerous meanings. For example, an Asus computer can report a surge that is a lower voltage. Power restoration is a surge of current meaning voltage is low and climbs slowly to normal levels. A USB surge is an excessive current. Another surge is a high current that results in a high voltage only where something tries to stop that current.

IOW the word surge is mostly to confuse and profit from the naive who do not demand characteristics and numbers associated with that word.

Same 'hype and spin' is associated with a phrase "surge protector". Numerous and completely different devices all share a same name. One to actually protect from destructive surges is completely different from another attached adjacent to an appliance. Protectors for destructive surges must be located within meters of earth ground. Protectors adjacent to appliances even have a history of compromising superior protection that already exists inside appliances. And in rare cases have caused house fires. Some so danagerous that APC recently demanded that some of their products be removed immediately.

Numbers are essential if making a recommendation. That power off with blackouts exceeding 2 hours is good advise.  The numbers also say why.

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