Surges do damage by finding earth ground via your equipment

[westom]

Split off of this post. JasonLion

So you'd go the whole home protection route instead of the at-panel point protection? Would it be overkill to do both?

First understand what a protector does. Does it block or absorb a surge? Protectors that do that do not claim to protect from destructive surges. The Intermatic protector does not do protection. It is only a connecting device to what must absorb hundreds of thousands of joules - earth ground.

Surges do damage by finding earth ground maybe via your controller. A surge connected to earth before it gets to a controller does not damage that controller. That means every wire inside every incoming cable must connect to earth. Either directly (ie a coax cable). Or via a protector (AC electric, telephone). Every cable must connect low impedance (ie less than 10 feet) to that same earthing electrode.

So view your situation as if one structure or two. For example, if pools and house are the same structure, then a 'whole house' protector must be where the main breaker box makes a short as possible (ie 'less than 10 foot') connection to earth. All other incoming wires must also make the same earth connection.

Or consider the pool and house as two separate structures (ie more than 20 feet apart). Then the pool wire must enter at the main box to be earthed by the main 'whole house' protector. And the other end of that wire must be earthed at the pool controller by its 'whole house' type protector. Also with a 'whole house' type protector. Any wires from the pool to its controller also must be earthed either directly or via a 'whole house' type protector. Only then will a surge current not find earth destructively via the controller (ie from pool, through controller to earth via something inside the house).

That incoming wire to earth can be via a protector inside a controller. So the controller must have a short (low impedance) connection to an earthing electrode. A safety ground wire (ie from remote panel to controller) is not an earth ground. That is only a safety (or equipment) ground. Your concern is connecting a surge to earth via the earth ground. And again, low impedance means short, no sharp wire bends, and that wire not inside metallic conduit.

Either a surge is earthed before entering a building (or pool controller). Or that surge is inside hunting for earth destructively via appliances. This concept was so routine and so well proven that damaging lightning strikes are considered a human mistake. If damage does occur, an investigation starts with the earth ground - the item responsible for absorbing surge energy.

Effective protectors (ie the Intermatic) must connect to what does protection. If that connection from Intermatic to earth goes up over a foundation and down to an electrode, then the Intermatic is compromised. That connection must be low impedance (shorter, no sharp wire bends). It must go through the foundation and down to an electrode. Because distance to single point earth ground is critical for effective protection.

A professional's application note demonstrates the concepts. In that case, the two structures are a building and radio tower. Each has its own single point ground. To make both grounds better, grounds are interconnected. The note shows even underground wires must be protected before entering either structure.
http://www.erico.com/public/library/fep ... ncr002.pdf

Too many confuse a protector with protection. A protector (Intermatic) is simple science. The protection (earthing) is an art.

 

[Safetybob]

Re: Surges do damage by finding earth ground via your equipm

This is a great post and does a great job explaining just how confusing and complicated protecting equipment can be. Whether it's your pool equipment, which seems to get more automated, or appliances in your home, electrical surging from the stuff the electric company does (how's that for over simplification?) happens in my town outside of Oklahoma City around 7 times a day. Add to that the once every other year direct lightening strike to a nearby tree, and I have electrical "protection" issues.

Whole websites could be created just on this issue. Realize this issue can go from crazy to really crazy. For the average homeowner, I would recommend you visually check your safety ground equipment outside and see if there is any corrosion or damage. Actually, call your trusted local electrician and have them inspect your fuse/breaker box and your outside grounding equipment if you don't feel up to it. After a major lightening strike a physical examination of wiring would be wise and may actually be paid for by your insurance company (be sure and ask if it happens). That's what I did for my last strike...

You can never "fail" to be safe enough when it comes to electricity.

Bob E.

 

[Safetybob]

Posts merged to keep detailed info in one place. Bama

Jragan, if you haven't seen, Jason broke off a wonderful response to this question off into another thread. Please read that post which I am sure you will be scratching your head over. It's great information in to the complexity of "grounding" and "protection" issues but may not exactly give you a firm answer for your question.

Here is an answer everyone can understand. Surge protection due to power company inducted switching of their power generation equipment OR surge induced by nearby lightening activity from thunderstorms is a matter of how much money you are willing to throw at it. "Protection" from a direct lightening strike on your home/pool equipment is a whole different thread.

For home surge protection, yes, a whole house surge protector at the entrance equipment can be looked at layer 1. Putting another plug-in surge protector on the device you want to protect is layer 2. Making sure ALL your safety grounds are working and connected to your entrance equipment is about all you can do. I will also advise anyone concerned with surge protection to purchase good stuff. One of my EE buddies who designs lightening protection for commercial buildings told me that these two layers of surge protection are just about all the average homeowner can do to minimize damage to equipment simply and somewhat cheaply. When he showed me what they do to protect real buildings from lightening strikes and what it would take to do the same for my house.......might as well as build a new house.....again, how deep are your pockets?

Having actually torn apart the cheap surge protectors and the really nice all metal APC surge protectors.....I prefer the metal APC branded ones mainly because of the safety that a metal box gives me versus some plastic that could smolder, overheat, and catch on fire. The insides of cheap and expensive are close to being the same, but the metal APC ones do have as good a stuff in them as they can get, unless you are willing to build your surge protectors.

Now, let's talk reality. How are you going to protect that $1,000 variable speed pump you just bought. Check with your electrician, but I can only see if you could install a surge device in or on the sub panel by your pump and pool equipment (I am thinking in-ground or big AGP here), you could protect all your pool equipment from electical surges, again, hopefully during a lightening strike the zap if coming from the house would meet the subpanel and find it's way to your earth ground at the subpanel before zapping your equipment.

Before doing much of anything on your own other than "plugging in" something, I would consult your local electrician.....particularly one who has done a number of pool installs.

Bob E.

 

[westom]

Re: Is Surge Protection Needed?

For home surge protection, yes, a whole house surge protector at the entrance equipment can be looked at layer 1. Putting another plug-in surge protector on the device you want to protect is layer 2. Making sure ALL your safety grounds are working and connected to your entrance equipment is about all you can do.

Layer one is not a 'whole house' protector. Each layer is not defined by a protector. Each protection layer is defined only by earth ground. Where hundreds of thousands of joules dissipate.

A picture demonstrates what Jragan, et al inspect for layer one protection:
http://www.tvtower.com/fpl.html
Layer two is a 'whole house' protector discussed in a previous (and moved) post.

Safety ground is irrelevant. Because of something that engineers (who do this stuff) quickly learn. If a connection from protector to earth is too long, then that connection all but does not exist. Distance to earth must be the shortest connection. Safety ground is too long, has splices, has sharp bends, and may be inside metallic conduit. Safety grounds violate some if not all such requirements. The other ground - earth ground - defines protection.

Same concept was taught in elementary school science. Does a lightning rod protect from lightning? Of course not. A lightning rod is effective when connected short to earth. Then lightning is absorbed harmlessly.

Same applies to every protector. When connected short to earth, then a direct lightning strike is absorbed harmlessly.

Either a surge (utility switching, fault created by a stray car, lightning, etc) finds earth harmlessly outside. Or it finds earth destructively inside via household appliances or via a swimming pool controller. Protection or damage is always about the path to earth. Protection is always about where hundreds of thousands of joules dissipate.

That same solution is always in every facility that cannot have damage. A 'whole house' protector even sold in Lowes and Home Depot for less than $50. A least expensive solution is the most effective. And is always found anywhere that damage cannot happen. It's not complex. But if new, then multiple rereads may be necessary.