Do these surge protectors work?

[themerg]

what are you protecting ?

[Crossy]

6 hours ago, themerg said:

what are you protecting ?

Pretty much anything electronic and mains powered.

 

Lightning induced surges are a significant problem here due to the prevalence of lightning (of course) and the major use of overhead power transmission lines.

 

Whilst nothing is going to save your kit from a direct hit, surge arrestors will kill any smaller (but still potentially damaging) transients on your supply.

 

 

[carlyai]

Got any Thai suppliers of the phase lightning protectors?

Got several sources from China.

Sent from my SM-J700F using Tapatalk

[westom]

On 8/17/2017 at 1:54 AM, tomas557 said:

Seems 100Ka is impossible to find.

 

The biggest can find is 60Ka Ln and 100Ka maximum discharge.

 

Lightning (a surge that must never cause damage) is typically 20Ka.  So a minimal protector is 50,000 amps.  Since an effective protector remains functional for decades after many direct lightning strikes.

 

Above defined protector life expectancy over many surges.  Also of concern is protection during each surge.  That is defined by how that protector connects (is hardwired) to single point earth ground.  Not just any earth ground.  Every wire in every incoming cable (TV cable, telephone, remote front gate) every wire must make a low impedance (ie less than 3 meter) connection to the same earthing electrode.

 

That N-E wire from the electric box can make that connection.  But again, it must be low impedance (ie no sharp hardwire bends).  No protector does protection.  Effective protectors connect low impedance (ie less than 3 meters) to what harmlessly absorbs hundreds of thousands of joules - earth ground.  Earth ground does the protection.

 

Best protection on a TV coax cable is a hardwire from cable direct to earth.  No protector required.  Telephone and AC electric wires cannot connect directly.  So a protector is doing what that hardwire does better.

 

Again, a protector number (ie 60Ka) is about protector life expectancy.  What makes it so effective for each surge is the connection to and quality of single point earth ground.  That connection determines if protection exists even from direct lightning strikes.

 

Makes no difference if incoming wires are overhead or underground.  Both can potential incoming surge paths.  Same protection must exist on every incoming wire - overhead or underground.

 

If any incoming wire connects to a different earth ground, then then entire protection scheme is compromised.  Separate earth grounds make household appliance damage easier.  The term single point earth ground is critical.

 

Most attention should focus on THE item that defines actual protection - those earthing electrodes.  Earth ground at the utility pole is too far away from the protector. 

 

However that utility pole earth ground would provide a 'primary' protection layer.  That electric box protector is the 'secondary' protection layer.  Any protectors attached to wall receptacles have no earth ground; do not do and do not claim to do effective protection.  Because a protector is only as effective as its earth ground.

 

[maxpower]

1 hour ago, westom said:

Lightning (a surge that must never cause damage) is typically 20Ka.  So a minimal protector is 50,000 amps.  Since an effective protector remains functional for decades after many direct lightning strikes.

 

Above defined protector life expectancy over many surges.  Also of concern is protection during each surge.  That is defined by how that protector connects (is hardwired) to single point earth ground.  Not just any earth ground.  Every wire in every incoming cable (TV cable, telephone, remote front gate) every wire must make a low impedance (ie less than 3 meter) connection to the same earthing electrode.

 

That N-E wire from the electric box can make that connection.  But again, it must be low impedance (ie no sharp hardwire bends).  No protector does protection.  Effective protectors connect low impedance (ie less than 3 meters) to what harmlessly absorbs hundreds of thousands of joules - earth ground.  Earth ground does the protection.

 

Best protection on a TV coax cable is a hardwire from cable direct to earth.  No protector required.  Telephone and AC electric wires cannot connect directly.  So a protector is doing what that hardwire does better.

 

Again, a protector number (ie 60Ka) is about protector life expectancy.  What makes it so effective for each surge is the connection to and quality of single point earth ground.  That connection determines if protection exists even from direct lightning strikes.

 

Makes no difference if incoming wires are overhead or underground.  Both can potential incoming surge paths.  Same protection must exist on every incoming wire - overhead or underground.

 

If any incoming wire connects to a different earth ground, then then entire protection scheme is compromised.  Separate earth grounds make household appliance damage easier.  The term single point earth ground is critical.

 

Most attention should focus on THE item that defines actual protection - those earthing electrodes.  Earth ground at the utility pole is too far away from the protector. 

 

However that utility pole earth ground would provide a 'primary' protection layer.  That electric box protector is the 'secondary' protection layer.  Any protectors attached to wall receptacles have no earth ground; do not do and do not claim to do effective protection.  Because a protector is only as effective as its earth ground.

 

Thank you. I passed onto our engineering dept.

[tomas557]

On 16/08/2017 at 0:34 PM, Crossy said:

The arrestor should go as close as possible to the incoming supply in order to be fully effective and have as short as possible cable to the ground rod.

 

3 single P 30ka ~ 60Ka arrestors arrived today. The larger for in the big box outside didn't arrive yet.

 

So to make things clear.

 

I have 3 RCD's in the DB. First RCD get the mains live feed. Second RCD get's it feed from the first one and third RCD get it feed from the secong one.

 

Q1 : Should I install an arrestor next to each RCD or is only one next to the one that get the mains feed enough?

 

As you know the current arrestors are at the end of the bus-bar, so I have to move them next to the RCD.

 

This may cause some wire shortages and ground connection slots in the DB, especially since I add one more arrestor this time, and if I can avoid buying a roll of 10mm wire that is appreciated of course.

 

Q2 : Can I go with the ground wire from the first arrestor to the second one and  from there to the third one, and from the third arrestor to the connection point in the DB ?

 

 

 

 

[tomas557]

18 hours ago, tomas557 said:

 

3 single P 30ka ~ 60Ka arrestors arrived today. The larger for in the big box outside didn't arrive yet.

 

So to make things clear.

 

I have 3 RCD's in the DB. First RCD get the mains live feed. Second RCD get's it feed from the first one and third RCD get it feed from the secong one.

 

Q1 : Should I install an arrestor next to each RCD or is only one next to the one that get the mains feed enough?

 

As you know the current arrestors are at the end of the bus-bar, so I have to move them next to the RCD.

 

This may cause some wire shortages and ground connection slots in the DB, especially since I add one more arrestor this time, and if I can avoid buying a roll of 10mm wire that is appreciated of course.

 

Q2 : Can I go with the ground wire from the first arrestor to the second one and  from there to the third one, and from the third arrestor to the connection point in the DB ?

 

 

 

 

 

Bump

[tomas557]

Ok found the answer actually in one of the previous posts, couldn't find it yesterday.

 

So since the DB's are close together a single arrester will be sufficient, which also makes my other question about interconnecting the earth wires unnecessary.

[Crossy]

1 minute ago, tomas557 said:

Ok found the answer actually in one of the previous posts, couldn't find it yesterday.

 

So since the DB's are close together a single arrester will be sufficient, which also makes my other question about interconnecting the earth wires unnecessary.

 

Yup, sorry about my tardy response, I have a day (and often night) job too

[tomas557]

12 hours ago, Crossy said:

 

Yup, sorry about my tardy response, I have a day (and often night) job too

 

No worries, but on closer look I decided to install 3 arresters anyway, because each arrester protects only the bus-bar it is installed on. At least that is my understanding.

 

So is it allowed that I go with the ground wire from one arrester to the next one, and only from the last arrester to the ground connection in the DB?

 

And I just stumbled on this, which made me confused about the N-E connection you suggested earlier.

 

http://smartpowersystems.com/2013/11/04/to-bond-or-not-to-bond/

The Dangers of Neutral to Ground Bonding in Surge Suppressors

Non-compliant Neutral to Ground Bonds
A non-compliant neutral to ground bond is usually easy to spot. Open a distribution panel and look inside. All of the branch circuit neutral wires, the white wires, terminate on a common bus. All of the branch circuit ground wires, the green wires, terminate on their own bus. If these are interconnected in any way, a violation of the NEC exists.

When we inject unwanted higher frequency current in the ground path, we are going to have this current wandering around the continuous ground path in a facility. This is bad enough at 60 Hz, but at 180 Hz and higher, the values of impedance change and parasitic paths are created inside the facility and interconnected equipment. If the cable interconnecting the network has a shield, then some of this ground current will split off and flow through that path.

 

My understanding here is, but I'm gladly corrected if I'm wrong, that in a surge the surge arrester sends the surge to the ground, but since ground and neutral in the DB are connected, some of the surge may return to the appliances over the neutral wire.

 

 

[Crossy]

5 hours ago, tomas557 said:

a violation of the NEC exists.

Which is a US standard. The US in general, doesn't use front end RCDs, so random N-E links won't have any visible effect other than splitting the neutral current all over the place (not good).

 

Thailand requires a N-E bond (MEN link) where the supply enters the property, it must be before any RCD protection (or the RCD won't stay on).

 

With N-E solidly linked any surge on the N will go directly to ground.

 

IIRC you have your own transformer with the neutral solidly bonded to ground at the transformer. Neutral is going nowhere significant on a surge front, if it does then you have bigger problems (like putting your roof back on).

 

Daisy chaining the grounds, so long as you keep everything short, should be fine. The secret with surge suppression is to keep all paths as short and straight as reasonably possible.

 

[tomas557]

2 hours ago, Crossy said:

Which is a US standard. The US in general, doesn't use front end RCDs, so random N-E links won't have any visible effect other than splitting the neutral current all over the place (not good).

 

Thailand requires a N-E bond (MEN link) where the supply enters the property, it must be before any RCD protection (or the RCD won't stay on).

 

With N-E solidly linked any surge on the N will go directly to ground.

 

IIRC you have your own transformer with the neutral solidly bonded to ground at the transformer. Neutral is going nowhere significant on a surge front, if it does then you have bigger problems (like putting your roof back on).

 

Daisy chaining the grounds, so long as you keep everything short, should be fine. The secret with surge suppression is to keep all paths as short and straight as reasonably possible.

 

 

Thank you for the clarification, I was worried about the N-E in the DB since that is close to the appliances, but I confused the neutral  from the incoming feed with the neutral from the MCB's

[westom]

On 9/8/2017 at 1:34 PM, tomas557 said:

My understanding here is, but I'm gladly corrected if I'm wrong, that in a surge the surge arrester sends the surge to the ground, but since ground and neutral in the DB are connected, some of the surge may return to the appliances over the neutral wire.

 

Remember how electricity works.  If that current is incoming on the neutral wire, then what is the outgoing path?  If both are not defined, then no electricity exists.

 

No outgoing path exists because that current already made a best connection to earth.  For your theory to be valid, earth ground must be compromised - is not a low impedance (ie wire has no sharp bend) connection.  But again, protection is always defined by the quality of and connection to earth.

 

That surge is incoming to everything - even with a properly earthed protector.  Since that protector is properly earthed, then no appliances have an outgoing path - no damage.