Voltage low as 74v after blackout. What's wrong?

Forums › Home Workshop DIY › Voltage low as 74v after blackout. What's wrong?

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#1995107 12-Apr-2018 23:42

Again, even if the problem is outside in the street, you can still get electrocuted inside your house. And this is NOT a fault that can be diagnosed over the internet. Note that the current flow will affect voltage readings. So even if you manage to measure the correct voltage using your digital multimeter, it is no guarantee that things are safe.

Sorry @Shin but the only safe thing to do is leave the power off until someone from Vector can come over and find the problem.

@michaelmurfy imagine you are in your car, and live wires have fallen on the car, making the whole car live. This is a similar situation, but with a house.

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#1995108 12-Apr-2018 23:43

@Aredwood Damn didn't think of this either but a very good point. With us we don't have a master breaker inside the house so had to turn it off at the street (unless if we were to trip every breaker). The hot water cylinder with us is controlled by the external breaker also. I actually wore rubber kitchen gloves turning it off in my case.

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Starscream122

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#1995110 12-Apr-2018 23:47

Nobody has any comment as to how somebody could get a electric shock from a garden hose which obviously don't have power going through them ? I have read the article twice to see if I'm missing something....

Shin

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#1995111 12-Apr-2018 23:48

@Aredwood Noted. Vector seems too busy at the moment. Will talk with next door if they also having similar problem. I wish Vector answer tomorrow. I will leave main as is for now. Main switch in the house is off at least

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#1995112 12-Apr-2018 23:53

Starscream122:

Nobody has any comment as to how somebody could get a electric shock from a garden hose which obviously don't have power going through them ? I have read the article twice to see if I am missing something....

"after she received a massive electric shock from a garden tap at her home in Perth"

Garden taps are often made of some sort of metal...

Starscream122

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#1995113 12-Apr-2018 23:55

Oh sun was shining on it my bad lol. I often get little shocks touching our car if it's really sunny. guess I'm lucky I haven't had a big one from it.... yet

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Shin

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#1995114 12-Apr-2018 23:57

@Aredwood @michaelmurfy just back to say thank you for the advice. good night! hope nothing bad happen tonight!

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#1995116 13-Apr-2018 00:46

Starscream122:
Nobody has any comment as to how somebody could get a electric shock from a garden hose which obviously don't have power going through them ? I have read the article twice to see if I'm missing something....

@Starscream122 that house probably has copper water pipes throughout. Those pipes will in turn be electrically connected to the earth wiring in the house. When the neutral fault caused the earth wiring to become live, the garden tap would have also become live via the copper water pipes.

Jase2985

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#1995131 13-Apr-2018 05:34

we had a low voltage problem before, it was the neutral cable from the over head line where it met house on the sofit, it was corroded out on only a single strand was left connected, when we turned on a few things the voltage sagged from 230v down to 120ish (dependant on what was running).

if you have overhead wires thats where i would be checking. you can also measure the voltage while you turn on high draw appliances like your oven and see if the voltage fluctuates. but once you have done that switch the mains off.

it requires vector to pull the pole fuses to remove power, so that an electrician can fix the problem on the house end, then vector can put the pole fuses back in.

vector are likely busy and a job like this may be well down their priority list.

Shin

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#1995139 13-Apr-2018 07:48

Vector still not receiving call and I have lodged outage yet another. Just talked with local electrician this morning about the situation. he said it is most likely transformer failure in local grid. Now I am confused. Better talk with next door soon

sparkz25

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#1995146 13-Apr-2018 08:19

as a registered sparky, and as @michaelmurfy and @Aredwood have said, turn the main switch off at the switch board inside and DO NOT TURN ON AGAIN untill the all clear has been given and a vector lines tech has been to your house!!!!!!!!!!!!!!!!

as for a couple of questions above about the garden tap, if you have copper pipes these are bonded, also water is a conductor, and if you have a hot water cylinder you also have a element in the cylinder which is in direct contact with the water, so in the MEN system if there is a crook neutral the return path will be the pipes / earth peg, because they are all at the same potential because they are all bonded at the switch board,

if the local sparky has said that its a tranny failure in the grid, still leave the supply off, as it could be a dropped HT fuse if thats the case and the 70v that you are getting is induction on the HT side to another HT winding with in the tranny and then thats not at full voltage so so it will be only half working as it is now.

the only way to find out is to ask the vector tech when he arrive, as he will be the only one who can test it properly!! DO NOT ATTEMPT your self

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#1995153 13-Apr-2018 08:52

I am in the same position. My street doesn't have overhead power lines and I just spoke to my neighbor who reports that his house has normal power. I might give my electrician a ring.

Edit: Other neighbors are all in the same position.

trig42

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#1995219 13-Apr-2018 09:39

There are still people around with low/no power.

We have three people at work affected - two in West Auckland with no power, on on the Shore with no Hot water.

Obviously a big event which Vector are working really hard to fix. Our office had no power all day Wednesday - had to get a Generator in to power up the server racks.

Dynamike

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#1995243 13-Apr-2018 10:13

I live on a farm and regularly get the same low voltage problem after bad weather.

It’s caused by one of the 3 high voltage fuses on a transformer pole tripping, which is easy to identify as it pops out of position and hangs down.

There’s one power point in my house that’s on a different phase to all the other power points, so I plug the fridge into that when I have this problem as it still runs around 200 volts, which is enough to power the fridge/freezer.

But unless you know the cause of the problem, be careful with electricity.

trig42

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#1995291 13-Apr-2018 10:40

@Shin - the Vector App is still showing outages in Dairy Flat. Saying tomorrow night for resolution at the moment.

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