Prevent high volatge Surge (380v)

[Greglsh]

Hi

we had the mis-fortune of someone stealing a cable at the power station down the road from us a few days ago. This caused 380v to go through our and a whole lot of other houses. This caused us about R20 000 damage to appliances and a few lights.

What I wanted to find out is, what can we install before the DB board that will "trip" if this ever happens again. I have spoken to a few"electrical" companies and they give mixed information. Some say we need to install a surge protector and other say no that is more for the high volatges of lightning not a power surge of 380V ect.

Please can somebody with electrical knowledge let me knwo what I should be looking for. I want to prevent this from happening next time(I know there will be a next time)

Thanks

 

[The_Ogre]

AFAIK its illegal to connecr anything bedore the db. Not 100% sure though

 

[P924]

275V Class 1+2 surge arrestor available from ACDC for about R1400. Must be installed by a qualified electrician. Goes in ripple box before DB board and then trips the breaker in the supply box at the meter (you could also put it in the DB box). Whether it will work or not, you will have to test.

 

[rrh]

Hi

we had the mis-fortune of someone stealing a cable at the power station down the road from us a few days ago. This caused 380v to go through our and a whole lot of other houses. This caused us about R20 000 damage to appliances and a few lights.

What I wanted to find out is, what can we install before the DB board that will "trip" if this ever happens again. I have spoken to a few"electrical" companies and they give mixed information. Some say we need to install a surge protector and other say no that is more for the high volatges of lightning not a power surge of 380V ect.

Please can somebody with electrical knowledge let me knwo what I should be looking for. I want to prevent this from happening next time(I know there will be a next time)

Thanks

I had the same thing happen to me, though through the municipalities fault, Caused R200K worth of damage.

• You did not have a power surge: you lost neutral / had a "floating" neutral / whatever (the description depends on the electrician).
• There is no real method of protecting against this condition, which should never happen.

OTOH you should have a category 1 or 2 surge protector fitted in your DB. This will protect against genuine power surges e.g. lightning.

Incidentally (according to the manufacturers of these surge protectors) the plug-based (category 3) surge protectors will not work without a category 1 or 2 surge protector in the DB.

 

[Prokkie]

It true that surge arrestors will do you no good. I would recommend a load control relay (LCR) with a contactor. In this case the LCR will detect an over voltage and trip the contactor which then disconnects the power to your house until the problem is rectified. Remember that all electrical work must be done by a competent person.
Example of a LCR
http://www.cbi-electric.co.za/products.php?PFID=245

 

[Sonic2k]

275V Class 1+2 surge arrestor available from ACDC for about R1400. Must be installed by a qualified electrician. Goes in ripple box before DB board and then trips the breaker in the supply box at the meter (you could also put it in the DB box). Whether it will work or not, you will have to test.

What he said, but they are cheaper from PHD POWERHOUSE DISTRIBUTORS.
The above is what I did and it DEFINITELY WORKS. Stuff stopped going pop when that was installed.

 

[rrh]

It true that surge arrestors will do you no good. I would recommend a load control relay (LCR) with a contactor. In this case the LCR will detect an over voltage and trip the contactor which then disconnects the power to your house until the problem is rectified. Remember that all electrical work must be done by a competent person.
Example of a LCR
http://www.cbi-electric.co.za/products.php?PFID=245

I spoke to CBI-Electric.

LCRs are used for the control of geysers etc.

They would definitely not assist in over-voltages due to lost neutrals etc. caused by stolen cables.

 

[Jab]

275V Class 1+2 surge arrestor available from ACDC for about R1400. Must be installed by a qualified electrician. Goes in ripple box before DB board and then trips the breaker in the supply box at the meter (you could also put it in the DB box). Whether it will work or not, you will have to test.

You don't need a Class 1 surge arrestor for domestic purposes. Any class 2 surge arrestor will do.
But a surge arrestor would not work in this case. Surge arrestor is designed for quick spikes, typically 4 to 16 micro-seconds.
They would not be able to safe guard against a constant fault like the one the OP had.
Surge arrestor also do not trip circuit breakers. They work by diverting these spikes to ground.

For the OP I would suggest installing a Over/Under Voltage relay (i.e. WCPT1 from ACDC) operating a small contactor.

This would also be the perfect place to connect a generator by simply adding another contactor for the generator supply.

 

[Jab]

I spoke to CBI. LCRs are used for the control of geysers etc.

They would definitely not assist in over-voltages due to lost neutrals etc.

This. LCR are typically used to turn off the geyser when the stove is used.

 

[rrh]

What he said, but they are cheaper from PHD POWERHOUSE DISTRIBUTORS.
The above is what I did and it DEFINITELY WORKS. Stuff stopped going pop when that was installed.

Mandatory class 1 / 2 surge protectors are included in the new electrical specs that were drafted over ten years ago. Unfortunately the new specs have not subsequently been promulgated so the surge protectors are still not mandatory.

That said, in this particular case - where the neutral is lost - surge protectors will not assist, a fact that I confirmed with the suppliers.

 

[ScottulusMaximus]

Had this before as well, nuked pretty much everything in the house until the maid saw the decoder smoking and tripped the power...

Not much you can do except hope it doesn't happen again, we built a cage around the substation so the feckers can't get in and certain neighbours keep the keys if the electric guys need to get in. Not sure if that's legal here though.

 

[Sinbad]

Had this before as well, nuked pretty much everything in the house until the maid saw the decoder smoking and tripped the power...

Not much you can do except hope it doesn't happen again, we built a cage around the substation so the feckers can't get in and certain neighbours keep the keys if the electric guys need to get in. Not sure if that's legal here though.

I run my entertainment and IT stuff off a 2kva line interactive UPS. It handled the 400V no problem, it's happened a couple of times. Microwave got toasted though ... :/

 

[ScottulusMaximus]

I run my entertainment and IT stuff off a 2kva line interactive UPS. It handled the 400V no problem, it's happened a couple of times. Microwave got toasted though ... :/

There we go^^ Stick your ''valuable'' stuff on a UPS, should protect it.

We had our incident years back before anyone had even dreamed of needing a UPS for anything, and they wouldn't fix it until we built the cage so it didn't happen again, that was probably the main reason for a cage...

 

[rrh]

Had this before as well, nuked pretty much everything in the house until the maid saw the decoder smoking and tripped the power...

Not much you can do except hope it doesn't happen again, we built a cage around the substation so the feckers can't get in and certain neighbours keep the keys if the electric guys need to get in. Not sure if that's legal here though.

Much the same ... I had a series of "bangs" (it sounded like a gunfight in a TV western) and was wondering WTF when I saw the smoke from my home theatre's amplifier ... came close to requiring that my jeans be changed

 

[Jab]

This lost neutral can also make a KWH meter go like crazy. Check your electricity account very carefully.

 

[jb30589]

We lost neutral one night and a few appliances died but the newer part of the house that had a new earth leakage switch just tripped and everything survived. It also didn't allow us to turn it back on until the neutral was neutral again.

 

[Sonic2k]

Mandatory class 1 / 2 surge protectors are included in the new electrical specs that were drafted over ten years ago. Unfortunately the new specs have not subsequently been promulgated so the surge protectors are still not mandatory.

That said, in this particular case - where the neutral is lost - surge protectors will not assist, a fact that I confirmed with the suppliers.

Indeed, I am not talking about losing the neutral.
In those cases the netural leg of the protector is also lost, and they will be rendered totally ineffective.
The surges I thought the OP was talking about were when the power is reconnected.
However, if you do this, you'll mitigate the issue. If you put large MOVs across the live and neutral of the plug sockets, that will clamp but it will trip the power all the time and probably become a short

 

[Jab]

Indeed, I am not talking about losing the neutral.
In those cases the netural leg of the protector is also lost, and they will be rendered totally ineffective.
The surges I thought the OP was talking about were when the power is reconnected.
However, if you do this, you'll mitigate the issue. If you put large MOVs across the live and neutral of the plug sockets, that will clamp but it will trip the power all the time and probably become a short

Surge arrestor are connected between the live wires and the neutral to ground. So if the neutral is lost it will still function.
Surge arrestors will simply become a open circuit when they stop functioning. If they trip the circuit breaker or earth leakage it only mean they're still functioning and have diverted a surge.

 

[itareanlnotani]

You can put in an ATS switch (Automatic transfer switch).

You'll need to check if you have 3 phase or 1 phase (sounds like you have 3 phase though).
They can be programmed to cut the mains if anything is dodgy from Eskoms side. Eg missing neutral, or power out of spec.

They're usually used for Solar or Generator installs for anti-islanding, but can _definitely_ be used to protect against bad power from the provider.

Essentially, they monitor the mains coming in. If anything is untoward, they cut that off. Usually this is to protect expensive equipment like generators, but there is nothing stopping you installing something like that for a house.

I've been looking at them for off-grid purposes for Solar.

Some more info here on my blog - http://goingsolar.co.za/
They're not cheap cheap though. Far Diesel is the reseller here for the Comap device I was looking at.

 

[schumi]

I have also lost a few devices due to theft, I have purchased a product from Clearline called Trip Connect 100, I have been told by multiple sources that it is developed to handle 380 volts over a sustained period and trips your electricity when it detects under voltage or over voltage. It costs me around R1600. Will report back if/when they steal the cable again.