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Question DetailsAsked on 12/12/2016

Do outside brand new AC/heating unit come installed with a surge protector against lightning storms in Florida?

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4 Answers


Not by default or built-in to the unit - that would be an optional accessory, typically at least $100-150 or so if installed while other work is going on at the compressor, or more commonly $200-350 as a stand-alone install.

And a couple of things to note - surge protectors do NOT protect against lightning to any measureable extent unless the hit was pretty far away so you only see a minimal line surge from it. They can handle (within certain limits - commonly not over about 500V) surges in voltage and extraneous low-amperage transients in the power, so they are useful in protecting your unit, just not specifically real good against lightning - more against the surges that occur when power is restored after a power failure or when lines cross in high winds or due to a tree falling across them. Because of the amperages involved in running the compressor, sometimes the surge protectors are put only on the control wiring, not the overall unit wiring, i.e NOT on the starting circuit or compressor or fan motors. heavier duty types can go on the main wiring feed - either as an on-the-unit component or as a surge-arresting circuit breaker in the breaker box. Electric motors are reasonably tolerant of the type of surges that a standard surge protector could protect against anyway, especially if they have a starting condensor as most do on A/C's.

One problem with surge protectors - if they absorb any major surge the protective units in them (usually MOV's) burn out (which is what they are designed to do), so you lose the protection from then on - basically a one-hit protection against significant surges. So be sure you get a unit built for operating equipment that has a significant and clearly visible status light on it, and make a point of checking it frequently to be sure the light is still on. (This is why small electronic device surge protectors have the small LED light indicating if the unit is still good or not.) There are more expensive (nearer $70-100 for the unit) surge protectors that kick-out the breaker in the surge protector which are FAR better - but it does mean any time it protects against a significant surge and burns out the MOV's, it will shut off power to your unit and have to be replaced. What it should actually do, but can mean multiple changouts a year in areas with a lot of power surges or lightning hitting the power lines. Or in areas with a LOT of surges, there are commercial units costing a couple of hundred $ (and about $100- per replacement module) that use plug-in breaker-like replacement protection modules you can replace yuourself without doing any wiring after it gets taken out by a surge. Any of these type surge arrestors will cost you about $100-200 labor for the normal off-the-shelf residential type unit, or commonly more like $300-500 for the replaceable-module type (because that takes a separate intermediate breaker box commonly).


For lightning protection (though note NO lightning protection system will totally protect against a direct hit or near-miss strike, because you are talking tens of thousands to millions of volts and tens of thousands of amps of current - commonly as much energy discharged in a fraction of a second as your house uses in a month or few). Lightning protection systems that may help protect your A/C would include whole-house lightning rod and supression system, with the lightning rods and household metal grounded to lightning ground rods (which are separate from and away from the electrical system ground rods), and if the A/C is especially prone to separate lightning energy (located away from the house) a rod and grounding system for that too - though given that most units are right next to a house usually lightning rods on the house will protect the A/C too - though it should be well grounded to a separate lightning ground rod near the A/C. The rods should all have one-way lightning arresting devices on them, to allow charges from the house or unit to go to the ground, but to prevent stray lightning charges in the earth (within reason) from travelling from the ground rods into the household electrical system - this is standard material any competent lightning protection specialist or lightning-protection trained electrician (few of them - usually done by specialty companies) should be able to install.

Whether the typically $4000 insurance claim amount from a residential lightning strike, and the personal safety issue, leads you to install a lightning protection system or not is a personal issue - because a typical household system runs around $2000-4000 complete.


One other thing to consider, first checking if your system already comes with it (many newer units do) is a restart delay relay, sometimes built into surge protectors designed for use on large motors and A/C - such as Tripp Lite and other companies make. What that does is delay the unit from restarting for typically 2-10 minutes after loss of power. It is actually required by some power utilities on new A/C and other large motor installs.

This delayed restart serves three purposes -

1) it has the incidental benefit to the power company of A/C and other large motor loads not kicking on as soon as power is restored, which dramatically reduces the surges that occur during reenergization of the lines - thereby reducing the severe loads on generators, and also reducing the risk of the restart loads kicking main distribution line breakers back off again. This is called a false restart, and commonly cause major line surges at times which can be much more damaging to equipment and electronics than the power outage itself.

As far as your unit goes, it has two advantages -

2) it prevents restart as soon as the power comes back on, which reduces the total current surge load on your home electrical system at restart (with reefers and lights and such omcing back on at the same time) thereby preventing breaker tripping due to that instantaneous load coming on, and also prevents restarting during the restart period when line voltage can be significantly low - which makes for hard starting and heating in the motor.

3) Another advantage, and probably the most critical, is it prevents immediate compressor restart after a power loss, because it would commonly be restarting against full load or even against liquid in the compressor from the low-pressure side (liquid that went through the evaporator unit and did not get evaporated because the blower was not putting heat from the airflow into the evaporator). This liquid, if it gets to the compressor, can make it try to start against liquid, which at leat makes it work much harder than it is supposed to, and can severely damage it - especially if a piston type compressor (albeit those are rarer these days). Making it sit a number of minutes after a shutdown (best if closer to 10 minutes) allows the outdoor heat and the residual heat in the system to evaporate any liquid from the compressor and low-pressure side so upion restarting it will be compressing gas, not liquid. Should be a mandatory part of all A/C and freezer compressors, but is not.

Some Heating and A/C companies install surge protection - especially the one-the-unit type. FOr more advanced surge protection, including that installed in the feed wiring to the A/C from or at the house or in the breaker box, and Electrical contractor would be your Search the List category. Lightning protection does not have a category on Angies List.

Answered 3 years ago by LCD



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Answered 3 years ago by Member Services


Many purchased near zero joule protectors with extragent prices. Suffered damage. Then used wild speculation to assume nothing can protect from lightning and other typically destructive surges. That is classic junk science reasoning.

Protection from direct strikes was originally demonstrated over 250 years ago by Franklin. Same techniques have been doing protection from direct strikes for over 100 years. But only in facilities where science replaces emotion, hearsay, advertising myths, and wild speculation.

For example, electronics atop the Empire State Building suffer about 23 direct strikes annually without damage. A telco CO will suffer about 100 surges with each thunderstorm. How oftern is your town without phone service for four days after each storm? Never. Technology is that well proven.

Reality that demonstrates direct strikes without damage is in every town. But marketed to the naive are protectors that do not even claiom to protect from typically destructive surges. Then the same naive consumers *know* nothing can protect from lightining.

Having disposed of lies based in technical ignorance; move on to solutions.

First, all appliances already contain robust protectoin. Your concern is a transient, maybe once every seven years (more frequent in central FL), that might overwhelm that existing and superior protection. Begin with numbers. Protection is always about where hundreds of thousands of joules are harmlesslyl absorbed. How many joules do the most expensive and yet near zero protectors claim to absorb? Hundreds? A thousand joules? Those surges so tiny as to be made irrelevant by protection already inside appliances.

A protector is only as effective as its earth ground. Then hundreds of thousands of joules dissipate harmlessly outside. Then no surge is inside hunting for earth ground destructively via appliances. Then protection routinely inside all appliances is not overwhelmed.

If anything inside needs protection, then everything needs that protectoin. Informed homeowners earth a 'whole house' protector - that costs about $1 per protected applince. With spec numbers that define protection even from direct lightning strikes. Only honest answers also discuss spec numbers.

Lightning is typically 20,000 amps. So a minimal 'whole house' protector (when properly earthed) is rated for 50,000 amps. Because effective protectors do not fail even with direct lighting strikes. Because protectors must remain functional for decades. Because this is how it was done even over 100 years ago. Because this is the only protection found in all facilities that cannot have damage. Because best protection is also least expenisve - therefore is not promoted by advertising and other urban myths.

No protector does protection. A protector is only as effective as the item that does protection. That harmlessly absorbs hundreds of thousands of joules. Protectors are simple science. 50,000 amps defined protector life expectancy over *many* direct lightning strikes over many decades. Protection during *each* surge is defined by the item that must have most of your attention - single point earth ground. Earthing is the 'art' of protection.

Protection is always about where hundreds of thousands of joules harmlessly dissipate. A protector is only as effective as its earth ground. Therefore a 'whole house' protection is effective and plug-in protectors are ineffective.

You should be asking questoins about the most critical item in every protectoin system. To be honest, those answers must include numbers. That item is unknown to a majority only educated by advertsing, myths, hearsay, wild speculation, and emotons. A protector is only as effective as its earth ground.

Answered 3 years ago by westom


Westom properly emphasized the importance of high-amperage capacity lightning protection, and that without a good ground (located far enough from your electrical system wires and grounds that it cannot "jump" to them or they are not significantly affected by the "halo" effect of increased coltage right around the ground rod during a strike. And there have been strike recorded (skyscrapers and antennas and NASA launch towers and such) in the 100,000 to 200,000 amp range - so while a 50,000 amp rated grounding system will protect against most strikes pretty well, it certainly is no guarantee it will handle it. The key of course is how long that current flows - whether it heats up the components enough to explode or melt them or not.

As both he and I said - surge protectors do NOT protect against anything near the voltages in a lightning strike - they commonly protect against nominal voltage (typically up to about 500-1000V) and up to maybe a few hundred amp milliseconds-long surges only and not at all against extreme voltages, which can just jump between components in the surge protector as it fries it. So - as he said for "true" lightning protection you need a proper lightning rod and grounding cable and ground rod(s) system - PLUS surge protection for at least nominal protection against surges coming through the electric lines from strikes or shorts or cross-voltage connections well outside your property which come through the power wires to your house, or stray voltage wandering around from a lightning strike either at your house or nearby on trees or the ground or such, because anywhere within dozens to over 100 feet from a strike, there can be lots of paths-to-ground being used by the lightning even if there are lightning rods. I remember twice, in different states, seeing ball lighting (ionized air plasma) "rolling" around on the ground for at least 20 seconds after a nearby lightning strike - some of the "balls" travelled at least 50 feet before finding a good enough ground to short to ground.

Plus the electrical code used in many areas requires (I think wrongly so) that lightning ground rods be "bonded" with wire to the house wiring system, on the theory that all elements of the house and electrical system should have a common ground to prevent voltage differentials between various components or elements. If this is done, you have to install good lightning arrestors, which are basically "shunts" or higher resistance paths that bleed high voltages to the ground rod) on that bonding cable, so you do not get a direct high-voltage surge right into your electrical system.

While the bulk of the energy should (hopefully) go into the lightning system ground rod(s), a certain percentage of it (which can still carry an immense amount of power and voltage) will take whatever route it can find - arcing to metal or wet surfaces from the lightning conductor or ground rod, travelling through or on the surface of the ground - or traveling through the bonding wire to the power system ground rod and ground/neutral cables, the latter which are commonly better grounds than a normal 8-10 foot ground rod. This is a basic flaw with common bonding - the voltage from the lightning will favor flowing to the "best" or lowest electrical potential ground - which is commonly the neutral and ground and any metal sheathing on the power company conductors. So - to prevent that, the current "best" grounding technology is to use either a deeply buried steel ground bus or plate, or a pair or trio of lightning ground rods connected to the lightning rods and any roof ridge "collector" cable, then have any required bonding to the electrical system and its ground rod going first to another intermediate ground rod preferably about 10 feet from the electrical system rod, as another path to ground for the energy, then a trip-out or burn-out type lightning arrestor on the cable to the electrical system ground rod which will interrupt the circuit in a millisecond or two if it get a strong hit of energy. The reason for the intermediate rod is that the ground around the main lighting protection ground rods will be highly energized (hence best to keep well away from electrical system) and will "see" the electrical system bonding wire and ground rod as a "good" ground - putting an intermediate ground rod in between the two hopefully gets it outside the energized zone around the ligthning ground rod and provides a safe energy dissipation point BEFORE it can get to the electrical system and its ground rod. The code dithers a lot on whether this bonding wire and lightning arrestors have to have a warning device to show it has tripped or burned out - in some areas that is required, in most others not though it probably should -- because obviously if it has "opened" or burned out the bonding circuit then that code- required bonding is no longer in existence. I have seen a fair number of bond wires (commonly real obvious braided copper wire in the old days) totally melted through at its connection point - clear proof that is carried a lot more power than it should have at some point in the past, and also that it had been totally ineffective since that time.

One other thing on lightning ground rods - to prevent immediate arcing burn-through you need to use heavier-duty lightning-rated full-contact or brazed/welded connection of the grounding cable to it so the connection is not burned away instantly, leaving the lighting energy to dissipate as it can - not just the bolt-on bronze diamond-shaped ones. These are usually wrap-around bolt-one bronze clamps like shown near the top of this reference - and personally I always have used two per ground rod because that is the weak link in the connecting components -

And because normal ground rods commonly do not provide real good grounds, for really good lightning protection it is commonly recommended to use 3/4 or 1" ground rods driven 15-20 feet deep, not the normal 1/2 or 5/8" 8-10 footers. Of course, the soil type matters a lot - a wet/very damp free-ion clay or organic soil can provide a good ground in less than 4 feet, as can damp salty soils and almost all soils below water table, while some dryer clean gravels, sands, and rubble/talus deposits I have had to go (for commercial/military applications) over 40 feet to get an acceptable resistance-to-ground reading - hence the use of "ground wells" in many applications in those conditions, and also for electronics grounding where a very good ground path is needed - sometimes calling for up to 200' ground wells for critical facilities like data centers, power plants, etc.

BTW - the soil "wetness or dampness" is important not because of the water itself - clean fresh water is actually a pretty lousy conductor - but because the water dissolves minerals and carries those free ions as well as dampening the minerals coating the soil - THOSE are what conduct the electricity. And no Bubba, tying the lightning rod to the rebar or pool ladder of the swiming pool or hot tub is NOT a good idea - either from a personal safety standpoint, or from the standpoint of how good a ground it will make. And yes I have seen both of those several times - including once on a professionally installed system on a highrise hotel building with rooftop pool. In the highrise pool case the installer though he would protect people in the pool from a strike by grounding it - not thinking that first the water would have conduct the electricity to the grounding point - through any swimmers - but also that the lightning might see the pool as a ground and travel from the very tall and numerous (and frequently hit) building and antenna ground rods down the grounding conductor TO the pool. Oops - my bad ? Nor was grounding the handrails at a major amusement park (which by itself was a good idea, having very long handrails along ride waiting line paths, in a very lightning prone area) to the same grounding system as the lightning rods were on a real good idea.

Answered 3 years ago by LCD

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