Protecting Electronics and Electrical Devices

Click on on the coffee-maker,  flick on the Air Conditioning,   toast your bagel, flip on the computer,  put on some tunes,  heat that mug of water in the microwave for tea,   and  print some documents  …   Each of these daily activities encounters different  types of Mexican electrical problems,  that commonly occur with CFE ‘s dirty electrical service.  … Then notice that each of those different activites requires different kinds of protection,  to protect our treasured toys from common electrical problems here.

A quick review of our daily electrical-lives reveals a basic list of common CFE problems we can choose to deal with (or not) … before they damage our stuff:

  • Constant low voltage (dropping below 105 VAC)
  • Constant high household voltage (132 – 140 VAC)
  • Transient voltage spikes & transient voltage drops
  • Voltage surges (voltage pulsing up in a wave)
  • Rapid ON/OFF cycling
  • Lightning strikes

Our  wide variety of home appliances, computers and electronics each~all  have different electrical properties & different weak points …  each with its own particular Achilles’ Heel… each requiring different protection needs.

Where to start?
… at the beginning? …
That takes us outside to the meter, where the electricity comes into the house.  If you want full home protection, we advocate using a good quality lightning arrester on each hot leg (gnerally 2 hot legs coming into our home) and even one the neutral wire coming into the house.   In the USA, most power companies provide modest lightning protection, so this is often not be a big an issue in Canada or the United States.   … Fortunately, Siemens, Eaton & Square D all make lightning-arretors (for about $200 – $400 USD).   

The next protection step as we enter the home:  Whole House surge suppression – on the oder of 30,000 Joules to 100,000 joules.   Leviton sells a decent whole house surege suppressor (37,000 Joule rated) for about $60 USD here_.  (Send me a comment below, if you are interested.)  ….  Home Depot sells the Siemens unit ( )… Whole house surge supressors protect the whole home from spikes, drops & surges, but they require a talented electrician to install them.

“…  Note, so many people on the internet tell us “You should buy this … blah blah blah” …  but realize that lightning strikes  powerful surges totally overwhelm all UPS’s (Un-interruptible Power Supply … aka ‘No Breaks’ in Mexico), …  Lightning strikes even overwhelm constant voltage transformers,  voltage stabilizers, line conditioners and generic surge suppressors in power strips => which is why you might want to install special lightning arrestors, IN ADDITION to surge suppressors, voltage regulators & power conditioners.

Mexican Lightning


~ Are you up to living in Mexico? ~  (click here)

Protect your phone, internet, and TV with line-filters :  

Note that good UPS’s and Line Conditioners/Power Conditioners can include sockets with line-filters to protect your phone/DSL/internet/cable TV  lines. Also note that good UPS manufactures like APC or Tripp-Lite include replacement-cost protection for consumer electronics losses due to power or DSL/phone power problems,   though these warranties often require that the UPS or Line Conditioner be purchased in the country where the damage occurs. ..   See places like Office Depot or Tripp-Lite dealer for your current options.  (punny?)

Next:  Rank what’s important to you … and protect it .
If fotos, documents, and electronic records are important … then focus on your computer … and MAKE BACKUPS that are NOT connected to CFE power.

What about the microwave oven or fridge with electronic controls,    or printer,  or high end stereo?   … the television …  or laptop computer? …   Unlike most internet advice,   modern electronics design says:  The TV and Laptop computer are likely the most robust devices in your house, since modern TVs and laptop computers have “switching”  power supplies (aka Switched Mode Power supplies … SMPS’s ) that IF they are good quality (LG, Dell, Samsung, et al) the SMPS’s easily and automatically handle voltages that range from 100V – 240V  (see the sticker on your power supply) –  and the SMPS’s  also generally have good surge suppression capabilities of 650 joules or more.

Power Outages – a very different issue from voltage spikes or surges:
A basic UPS offers good protection from power black-outs for our computers, disk drives, printers and all-in-one machines, BUT  most UPSs give   ~only~  back-up power protection … and nothing more – no real surge supression, and often no voltage stabilization. … Example:   To get bare minimal Surge Supression (500J) in a UPS (No Break) … costs over $350 USD in the USA … and over $8,500 pesos in Mexico.

Most UPS’s (‘No Breaks’)  do NOT give adequate protection for typical power surges,  power spikes, nor dirty power …  Most UPS’s also do NOT generally protect us from consistently-high voltages that are so VERY common with CFE’s local transformer issues.   The last 2 APC brand new UPSs we had gave NO adjustment/correction/protection from our block’s transformer tap set at 135V-140V.

Then  notice that stand alone surge supressors costing less than $75 US dollars, really are not designed to protect equipment from Mexico’s common power problems.
That’s why it’s far far better to buy a real (dedicated) voltage regulator- power conditioner (costs just $1500 pesos) – that regulates Mexico’s wildly high & wildly low voltage … versus buying a UPS that is really are not designed to protect from Mexico’s common voltage problems.
This is APC’s UPS that has minimal (500 J) of surge supression – but costs over $8000 pesos. for that minimal protection.

burned circuit board

Why is Mexican Electricity such a problem??

Mexico is a “Type B” power provider, offering electricity at 127V +/- 10%.
This means that our Mexican household voltage can vary between 114V to 140V and still be “in spec” . …  Shocking, eh, since voltages over 132V can damage printers & microwave ovens and some Inverter fridges.

Still, buying a good UPS’s gives us some time to do controlled shut-downs of equipment during power outages. …  BUT UPS’s do not generally protect your valuable equipment from voltage surges  … nor from damaging constant high or too low household voltage.

When we first moved to Mexico 13 years ago, we lost our big workhorse old-school HP Laser-Jet (a $450 USD printer) to constant voltage at 137V ,     for which APC had to reimburse us $450 USD –  because the “modern” APC UPS’s do NOT use the big old-school  heavy constant-voltage transformers of old-school UPSs … which means ONLY 2006 and earlier UPSs often have large transformers that are set up as either voltage stabilizers that work on low (drooping) and HIGH voltages – and absorb voltage spikes.   Newer UPSs (post 2006) have less & less surge suppression, and often NO protection from typical 135 – 140 V CFE power (especially true if your home is close to the block’s transformer). … ALTERNATELY, Sola Basic (a dandy Mexican company) sells 400VA whole house power conditioners, designed specifically for MEXICO …  power conditioners (Corectores) that lock CFE voltages within the safe range of 107V – 130V … and they superblyt absorb voltage surges … but they cost about $300 USD each & require an electrician to install them.

Sidelights … Note that many voltage protection devices are not made to withstand the rigors of common Mexican CFE issues,  as even Mexican made KOBLENZ units are unreliable over time,  and APC products must have a “127V”  switch to accommodate CFE problems.

Conclusion:   Constant voltage transformers and ~ Line Conditioners ~  … and some Voltage Stabilizers with large transformers   offer the best voltage control, but they use power all the time and can create a fair amount of heat, (which is good if you live in Minnesota, but not so good in the Yucatan).    Voltage Stabilizers and Line Conditioners moderate both low and high AC line voltages back into reasonable ranges, providing stable clean power that is safe for computers and peripherals – but they are NOT cheap => $100 USD – $600 USD.

Less expensive UPS’s (less than $100)  and some modern manufactured UPSs since 2006, rely on fast electrical switches to change to battery power when there are voltage drops on the line or when there is consistently low voltage. These new cheaper UPS’s do  not  protect from high household voltage or voltage surges. Even though these new UPS’s cost less, weigh less, protect from small/tiny momentary voltage spikes, and do not put out the heat of the older voltage-stabilizing models … they simply do not protect electronics from constantly high voltage or from larger or prolonged voltage surges.

pixilated Slingbox TV  If you want full protection, plan to spend $100 USD or more on a good UPS, to protect a fridge or TV … that includes voltage stabilization of low household voltage (104 VAC – 105 VAC) and high household voltage (133 VAC – 140 VAC), along with battery backup.  …  Or … buy the cheap UPS for its battery-backup feature (to give you time for controlled shut-downs during power outages) … and PAIR it with a good voltage stabilizer – each costing $75 – $100 US dollars,  so, the pair can give protection equal to a $300 all-in-one power conditioner.

= = = = = = = 
The next point to consider for power problems:  Know that some lightning arresters on your AC power lines do not stop lightning spikes coming in on phone lines or cable-computer internet lines or TV-cable lines – though note that some of the Siemen’s units listed above do provide cable-TV, internet, phone line protection.   If you don’t have the Siemen’s data-line protection, then lightning surges coming in through internet/TV cabling must be addressed right at the source ~ like at your primary modem/router ~ to make sure the board-melting surges don’t fry your cabled ROKUS, computers, etc.    This means putting a serious surge supressor (NOT a cheap power strip)  in the ethernet line(s) coming out of the router.   ….  Also note that some telephone and cable TV & internet providers reimburse their customers’ losses due to fused, fried, or melted electronics from lightning strikes.   If this happens to you, inquire with your internet provider, as Cablemas has twice re-imbursed us for strikes that came in through their cables:

= = = = = =
UPS Selection Advice:  
Consider how many watts of power the UPS can provide (600VA, 1000VA, etc.) versus how big your loads are.    Take into account how long you need your computers, routers  et to run on UPS battery back-up.   Multiply the total amps of your load(s) x 120V,  and match it to the UPS capacity.     A typical computer uses only 200W-400W (2A – 4A) – meaning a need of  400VA to give you 5 minutes or so to finish your work and shut down the computer.  If you want longer voltage outage protection, buy an 800VA or 1200VA or 2000VA UPS.   If you want hours of computers, internet & router running during CFE power outages, consider having a good electronics tech install two marine deep-cycle batteries – beside your big UPS – where the big UPS keeps the boat batteries charged, and can give you a day of running a fridge, internet router, computer & a light or two … all on battery power. 😉
(and yes,  we offer this option) 😉

If you want even better protection, consider buying a Line Conditioner in addition to the UPS’s battery back-up capability. Line conditioners clean up a wide variety of noise, dirty power, spikes, voltage variations, frequency problems, and surges, but they do not include battery back-up.


Appliance Protection:   Microwave ovens are our household appliances most sensitive to power problems.    As such, our microwave ovens are usually the next thing to consider protecting.

Newer high power 1600 Watt microwave ovens seem particularly sensitive to Mexico’s power problems.   Their unusually higher power demands seem to push the limits of the modern oven’s electronics.    Just like the modern UPS vs old-school UPS issues:  even minor power problems can damage your shiny new modern micro-onda in ways that don’t affect older robust micro-wave ovens.
electric meter

Since microwave ovens use much more power (1600 watts) than your computer (50 watts – 200 watts), or TV …. the typical UPS that works for your computer simply does not protect a new microwave oven.    Microwaves need a dedicated very fast, specialized voltage stabilizer designed for electronics (read the box,  some stabilizers are designed for  “liñea blanca”  fridges / dryers / washing machines – devices with motors – while microwave ovens et al need the “electronics” version of voltage stabilizers. … Again, Sola Basic offers GREAT tailored options.

Note that appliances with motors require yet different models of voltage regulators than for protecting electronics, TV, printers & scanners …  which are different still from the voltage regulators designed to protect microwave ovens.

Modest quality entry-level high-capacity (1,600 W) voltage stabilizers cost $75 – $120 USD. Unlike UPSs, voltage stabilizers offer very good voltage control and modest voltage spike protection.   Their voltage spike protection is typically good enough to protect microwave electronics controls circuits from common Mexican CFE issues. Their combination of high power output, voltage stabilization, excellent surge suppression, and some voltage spike protection make them a good option to protect your microwave oven or your refrigerator.

If your refrigerator (or washing machine or clothes dryer) are old-school and do not have electronic controls (no LED displays), then they probably DO NOT NEED protection.   If instead, your appliances do have electronic controls or LED displays, then they could benefit from voltage spike and surge suppression protection, as provided by a good quality surge suppressor ($30 USD – $50 USD for a Tripp brand suppressor).   Refrigerators and clothes dryers and washing machines run for years without experiencing power-related problems –  unless your clothes dryer  or fridge   uses thermistors to measure temperatures

…   Thermistor-based temperature sensors in some clothes dryers give false HIGH readings when CFE voltages fly up above 130V … meaning your dryer may shut off too soon (thinking it’s too hot)  when set to “Auto-dry” settings if your CFE voltage runs high …  same issue happens in reverse for some electronic-controlled fridges with thermistor sensors.

What about air conditioners?  In general, air conditioners only need to be protected against direct lightning strikes and the lowest-tech problem … ants.

To protect against lightning striking a power line or transformer (the only way it would affect the air conditioner), you can turn off the breakers that lead to those appliances when a storm is imminent.   Ant protection is a different matter … needing powdered insecticide …   Ants and termites use our electrical conduits as super-highways once inside the walls – with off-ramps directly into our air-conditioner circuit boards.

Solution:  Sprinkle ant powder or boric acid in the bottom tray of the air conditioner’s circuit board compartment – and possibly at the bottom of electrical outlets. Remove the covers – don’t touch the wires, contacts, or boards,  and use a little rolled paper tube/funnel to  sprinkle the powder across the inside of the bottom of the compartment or outlet, and replace the cover.    This generally gives good protection for warm toasty circuit air conditioner circuit boards from becoming an ant nest – as has happened twice in our Merida home. …

Stressed out mom

Protecting Stereos, Satellite Receivers, Household Electronics etc: 
All of these devices benefit from some protection, but they are nowhere near as sensitive to power problems as desk-top computers or microwave ovens.   These things do not use much power (watts) which means a good but cheaper UPS + plus a modest (1000W) voltage stabilizer, or a good voltage suppressor ($30 – $50 USD) can do the job.

Since these devices are typically not sensitive to higher household voltage, the cheaper ($40 – $90) UPSs or cheaper lower power voltage stabilizers (1000 watt – $75) work fine – unless you have big voltage spikes from a big air-conditioner turning ON and OFF (yours or the neighbors?) ….

Note that laptop computers & TV’s typically tolerate between 100 – 240 VAC with no problems, but TV’s do NOT like being jolted “ON” and “OFF” rapidly.  …  The “ON” and “OFF” rapid cycling problem often occurs when CFE loses power at a transformer or switch and works on them … => HUGE issues.   …  We  often have a brief blackout, but when CFE linemen ram the big gate switches back ON, they sometimes make 3 – 4 attempts to slam the switch (gate) shut. …  The result?   Power coming into your home bounces wildly ON and OFF multiple times as they try to slam shut the big knife switches up by the block’s transformers.  (Apagadores Cuchillos)

Some better quality voltage stabilizers and UPSs have a short time delay built in before they send power to your TV, refrigerator, or microwave – a delay which may give protection from CFE’s ON-OF rapid cycling events.   UPS’s rapidly switch to battery backup, so, they too may protect your devices from the jarring “ON” – “OFF” cycles that happen when the power company is having or fixing problems.

Power Strips as Surge Suppressors:
Why have power strips been left out of the discussion so far?
The actual surge suppression capabilities of most ($10 USD) power strips are nearly useless in the real world.    e.g. How much protection do you get from an annual $50 auto insurance policy?  The same applies for $10 power strips. Power strips are very useful for turning things completely “OFF”, to save both electricity and to protect devices from power problems while not in use.  … Use a cheap power strip to rapidly & completely shut off microwave ovens, TV’s, receivers, etc at night or when you are out of the house, to save electricity and reduce pollution, but don’t trust them to protect appliances or electronics when they are switched on.  There are more expensive power strips (like the Belkin Conserve Switch Surge Protector with Remote (F7C01008q) for $40 USD ) that offer 1000 joules of surge protection.   For context:  650 joules of surge suppression is a minimum value to protect electronics etc.

Ground Problems:    In many poorer countries, the neutral leg  ( “ground” = “tierra“) of the public utility’s power lines is often NOT grounded, or it is only poorly grounded. This can cause some microwave oven transformers to explode (!!), and can damage some printers and other devices.   Unfortunately, it can be wise to test whether the important key outlets in your house to see if they are actually grounded – (which requires finding a good earth ground).

Polarity & grounding issues should be corrected only by a qualified electrician  (difficult to find in some poor countries).

meter and CFE card

Protecting Our Stuff:   Even when we match the solution to the problem,  the quality of the protective devices we buy makes all the difference.  …  Sola, Tripp, Fluke and APC have decades of reputations for making good quality components … and are available here in Yucatan.   More cost-conscious homeowners can consider Mexican and Chinese manufacturers with an eye toward knowing that quality control from unit to unit can be spotty.

I’ve have tested six individual Koblenz brand voltage stabilizers ($75 USD each), and two of the 6 actually boosted 120V up to a circuit-damaging 145VAC, ruining a $300 Mosquito Magnet trap and damaging a clothes dryer.   Four of the other five Koblenz brand voltage stabilizers worked fine for the last 4 years – while one went screwy in Year 3.   and 2 more failed in years 4 & 5 …  Is it worth saving $$ by buying a CHEAP Koblenz unit ???

In any case, it is wise to use a good quality volt meter to measure voltages at key outlets in your home, and also to test the net resulting voltages coming out of your “protection” devices. Even some better quality manufacturers, like APC, sell cheaper devices that don’t work as advertised (causing us the loss of a $450 HP laser printer).

In my 55 years of monitoring and massaging power quality, we’ve had zero problems with Tripp, Fluke or older Sola devices.

Disclaimer:  All of the above information is for education and entertainment purposes only.  Contact a qualified electrician to evaluate problems.  (

Note that a good qualified electrician with at least 10 yrs of Mexico-electical-experiences….  can do an energy-electricity audit on your home, using very specialized equipment, to find voltage leaks, shorts, opens,  mystery power drains, CFE meter problems,  Solar system installation issues, grounding issues etc.   A basic solid 1 hr audt costs about $50 USD – but can buy a whole lot more $$ worth of peace-of-mind … 😉

Why did I produce this article today?
A friend’s home has been having serious CFE problems for the last 6 months …   with their battery backup units beeping infrequently … (but too often)  …. flickering lights …. with the problems reaching a peak today when the power went out completely at 7:00 AM … their bi-directional meter stopped working … the CFE voltages on L1 & L2 were at 122V & 124V after I installed diablitos in place of the non-functioning meter. …  but the L1 vs. L2 voltage was only at 204V  (a phase issue) …   and within ½ hour,   the L1 – L2 voltage drooped to just 187V  … not enough to run 220V air conditioners or 220V pumps …   and then 10 minutes later… L2 fell to just 1.4 V   …   leaving CFE’s “220 V” service at … 122V …   *sigh*
Moms Underwood Typewriter
This meant re-wiring various breakers on their main panel –  moving them from L1 … over to L2 … to make the water pump run … to power the battery backup UPSs … to power their internet router …  and to open the heavy garage door.  …   CFE may come out today … (or not) …
*     *     *     *

Feel free to copy while giving proper attribution: YucaLandia/Surviving Yucatan.
© Steven M. Fry

Read-on MacDuff . . .

6 Responses to Protecting Electronics and Electrical Devices

  1. Pingback: Just another day of … Life in Mexico … | Surviving Yucatan

  2. sdibaja says:

    when was this article written?

  3. dean devolpi says:

    read you water pump one today. I did not grow up in a salt air area of the USA. Or a real high humidity so I am learning with the school of hard knocks as an Engineer too. A couple of suggestions I have for people. When replacing AC units if you can afford it put in inverter AC units as they are so much more efficient and they also do not cause severe low power conditions. If just filling a tinaca buy a low watt water pump, I actually recommend a RV water pump for 120VAC as these can run dry for a time without damage, and super low wattage. I actually use this after hurricanes with a 12volt DC RV pump hooked up to a battery for my place.. And they have plastic components that just do not rust out and freeze. I have a AC one and DC one that have lasted about 15 years now. I do use a 1/2 HP pump for normal use when city water is not on. But I sometimes have 20 something people visiting for a week or two. For pools always buy inverter pumps or at least a 2-speed pool pump if not inverter pump and replace the one you have right away as with the high electric rates it will pay off in as little as one year for a normal sized pool and 3 with a small pool..

    When changing light bulbs put some vaseline on the screw in part, and dip or smear some on all electrical plugs before plugging in.

    In theory same with new microwaves and even refrigerators, washing machines have inverter motors. These except for the microwave all do not have the 3 times rated current inrush that can cause many problems.

    I just replaced a circuit-breaker box today that was about 20 years old because it had a high voltage drop and my AC was causing my power backup to kick on.

  4. Pingback: A Foto Tour of Mexican Currency | Surviving Yucatan

  5. Ken Graham says:

    We have a hotel in southern Mexico, PlayaLindaHotelTapachula. com and my 1st comment when you are experiencing variable power is to put on Electrical Safe Rubber Glovers and use a Insulated handle screwdriver (or allen driver bit) and even better get an electrician to check and tighten the screws for power and Neutral, particularly Neutral. When I wired my 1st residence in Canada the Electrical Inspector came along and pushed my really tight connections back and forth a few times, then i had to tighten them up again. His comment was that the stranded wires needed to this to accommodate themselves and be re-tightened other rwise over time they would loosen. After tightening the second time and then pushing the wires again they did not loosen. Sure enough a year or so after our hotel was built I noticed our UPS volt meter moving up and down rather freely and yes the Neutral wire in the main panel was able to be tightened further.

    We found regular surge suppressors quite useless by themselves, however a surge Protector like Koblenz pv-15 and another brand (no name brand we picked up on Ebay) that cut out on high around 130-140 and low around 100-110 then delay about 1 minute before reconnecting to be good, and cheap at about $10 U.S. Unfortunately it is a single plug but you can put a multiplug outlet after it. Also you can use ahead of your UPS . Or after that overpriced Koblenz unit that is supposed to vary voltages but still seems to let surges through. The delay is important as it gives your refrigerator compressor time to settle and also takes care of the surge or low voltage that comes about during reconnection.

    Another, Mexico seems to have issues with the single phase meters – those smart meters are not able to accomodate when amperage gets upwards of their 100 amp limit, and they have none for 200 amps single phase. The Power commission does however suggest you use a 3 phase meter base and they will come and install a 3 phase meter on single phase line and evidently the billing is still calculated properly, just that 1 leg of power meter is always zero. This allows you to get over the 100 amp limit of a regular meter. I’ve read there have been some issues in Canada with those smart meters not handling the amps, so am wondering if they also will end up needing a similar rewiring using a 3 phase meter base?

    While there was a mention of using Vaseline on light sockets in comments another option is to buy Die Electric Silicone at your auto parts store like Autozone. This is used in spark plug boots to keep out moisture and can take both heat and voltage.

  6. sdibaja says:

    I too have experienced loose connections at both sides of the meter, and in the service panel over the years also. They do need to be checked and tightened periodically. I learned that growing up in a ranch setting 70 years ago.

    Last fall:
    I was having low voltage alarms on my grid-tie solar system, and some cheap LED bulbs were flickering, just in the evenings.
    My solar system was switching to the battery bank so I was OK, I only noticed the LED flicker from the low voltage brownouts.

    Our CFE transformer has a 30 meter run to a service pole, then from that service pole there are 4 drops to homes. Two are vacation homes seldom occupied.

    The cable from the transformer to the service pole had 7 copper strands, 10 gauge each. After 25 years of corrosion, 4 stands had broken.

    When one neighbor came home from work in the evening they were overloading those 3 wires, they were having severe brownouts, they complained.

    That bad cable was replaced with Two cables of the same type.
    Problem solved.

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