Residency & Law / Protecting Electrical Appliances in the Tropics

Protecting Electrical Appliances in the Tropics

Protecting Electrical Appliances in the Tropics

8 May 2012 Residency & Law 14

Editor's Note:

If you have lived here for any length of time, you have no doubt been forced to contend with some breakdown of our appliances or electrical system. When we first moved here, one of the first things we dealt with was an apagon, a blackout that was widespread throughout the city of Merida. Over the years, we have dealt with washing machines broken down because of a build-up of saro (calcium carbonate from the water), computers with burned-out motherboards due to lightning strikes, electrical outlets rendered useless due to ant nests and all sorts of other appliance and electrical complications. Ah, the tropics! In this article, Dr. Steven Fry brings you some helpful suggestions on how to protect your appliances and electrical systems from the slings and arrows of outrageous electrical currents. As always, we welcome your comments or additional suggestions!

Mexico's Electrical Issues

We have noticed that there is a thirst for information on the practical aspects of using electricity in foreign countries like Mexico. Because of that, and because there are things that we can do in the area of prevention and caution, we are bringing you this information which we hope will save you money and make your future power experiences less shocking.

To kick things off, it is worth considering the different types of electrical quality problems that commonly occur with Mexico's electrical service, provided by the state-run organization affectionately known as CFE. The most common problems with electrical power service here are:

  • low voltage (dropping below 105 VAC)
  • high household voltage (134 - 140 VAC)
  • transient voltage spikes & voltage drops
  • voltage surges
  • rapid ON/OFF cycling
  • lightning strikes

Practical protection schemes are complicated by the wide variety of appliances and electronics that typical expats use, and which are increasingly used by all Yucatecan households. Because household appliances, electronics and computers all have different electrical properties and different needs, each category also needs different types of protection for its particular Achilles' Heel.

Protecting the Whole House

Let us start at the beginning... at the meter, where the electricity comes into the house and is measured by CFE. At the meter, we advocate using a good quality lightning arrester on each hot leg coming into the house. In the USA, most power companies provide some amount of lightning protection, so this is not usually an issue in Canada or the United States. Even there however, you might have a backyard lightning collector system (you probably call it your sprinkler system...) with metal heads and metal/copper plumbing that gathers lightning and can pass it into your home. Lightning arresters, installed just after the meter, help protect your entire home from lightning's huge voltage and current surges. These powerful surges generally overwhelm UPS's (Un-interruptible Power Supply), constant voltage transformers, voltage stabilizers, line conditioners and surge suppressors.

Cautious readers might note that lightning arresters on your AC power lines will not stop lightning spikes coming in on phone lines or cable-computer internet lines or TV-cable lines. (Working Gringo note: That is exactly how we ended up with a fried motherboard one day. We had unplugged everything that was plugged into an electrical outlet as a big storm approached. When lightning struck the telephone pole outside our office, the motherboard of the computer connected to the DSL line melted instantly.) Fortunately, some telephone and cable TV & internet providers reimburse their customers' losses due to roasted, fused, or melted electronics from lightning strikes. If this happens to you, inquire with your provider before you buy new equipment.

If you want to protect your phone, internet, and TV, there are special filters available, and many good UPS's and Line Conditioners include sockets with filters to protect your phone/DSL/internet lines. Good UPS makers include replacement cost protection for consumer electronics losses due to power or DSL/phone power problems. Many of these warranties require that the UPS or Line Conditioner be purchased in the country where the damage occurs. This means US-purchased protectors do not reimburse losses if and when your UPS or Line Conditioner fails in Mexico. You can buy this equipment in Mexico (at places like Office Depot, for instance), but the range of available choices is limited.

Protecting Computers

Since our photos, e-mail correspondence, documents, and images are often more important to us than the microwave oven or the television, let's start with basic computer protection.

Most people consider a basic UPS to be enough to protect their computers, drives, printers and all-in-one machines, so it is good to understand what exactly a UPS offers in terms of protection.

All UPS's have batteries to give you some time to do controlled shut-downs of your devices during power outages. They do not generally protect your valuable equipment from voltage surges or high household voltage. UPS's made earlier than about 2006 typically have large transformers that are set up as either voltage stabilizers or even constant voltage transformers, offering some protection. Constant voltage transformers and Line Conditioners or Voltage Stabilizers with large transformers offer the best voltage control, but they use power all the time and 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 their peripherals. However, please note our mention of "UPS's older than 2006".

Most less expensive UPS's, those that cost less than $100 and manufactured 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. The new cheaper UPS's do not protect from high household voltage or voltage surges. High voltage from your neighborhood transformer (e.g. 134 VAC - 140 VAC) coming in every day, 24 hours a day, is not down-regulated by these new-style UPS's. Though these new UPS's cost less, weigh less, protect from 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 prolonged voltage surges.

If you want full protection, plan to spend $100 USD or more on a good UPS that includes voltage stabilization of low household voltage (90 VAC - 105 VAC) and high household voltage (134 VAC - 140 VAC), along with battery backup. When you choose your UPS, it is good to consider how many watts of power the UPS can provide (600VA, 1000VA, etc.) versus how big your loads are. Also you should take into account how long you need the UPS to run on battery back-up. 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.

Household Appliance Protection

Microwave ovens are the household appliance most sensitive to power problems. This means that when deciding what to protect and what to ignore, 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. The unusually higher power demands of these new ovens seem to push the limits of the manufacturer's components. Even minor power problems can damage your shiny new oven in ways that would not affect an older, more robust lower power oven.

Since microwave ovens use much more power (1600 watts) than your computer (50 watts - 200 watts), the typical UPS that works for your computer simply does not produce enough amperage or watts to drive a new microwave oven. This means that microwaves need a dedicated voltage stabilizer. Entry-level high power (2000 W) voltage stabilizers can be bought for $75 - $80 USD. Voltage stabilizers offer very good voltage control, and offer modest voltage spike protection. Their voltage spike protection is typically good enough to protect microwave electronics controls circuits. 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 even need protection. If these 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). Typically, refrigerators and clothes dryers and washing machines run for years without experiencing power-related problems, but if you have a voltage stabilizer in your kitchen for the microwave oven, you might as well plug the refrigerator into it also.

Other important household appliances are 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. It will be harder to protect against ants. Ants use the electrical wiring conduits as highways once they get inside the walls. A good way to protect against ants in general is to sprinkle ant powder or boric acid in the bottom of each electrical outlet. Remove the outlet cover and sprinkle the powder across the inside of the bottom of the box, and replace the cover. Use care to not touch any exposed wires or electrical connections. This will not categorically protect an air conditioner from becoming an ant nest, but it will definitely help. Ceiling fans, by the way, need no protection.

TV's, Stereos, Satellite Receivers, and Household Electronics

All of these devices can benefit from some protection, but they are nowhere near as sensitive to power problems as computers or microwave ovens. Also, these devices do not use much power (watts). For both of these reasons, either a good but cheaper UPS, or a good but less powerful (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 - $35) work fine for TVs or stereos. TV's typically tolerate between 100 - 140 VAC with no problems, but TV's do NOT like being jolted "ON" and "OFF" rapidly. The "ON" and "OFF" rapid cycling often occurs when CFE loses power at a transformer or switch. There will be a brief blackout and then when they throw the switch back on, they sometimes make 3 - 4 attempts to slam the switch (gate) shut. The resulting power in your home bounces wildly on and off.

Voltage stabilizers usually have a short time delay built in before they energize and send power to your TV, refrigerator, or microwave. That built-in delay time gives yet ANOTHER type of protection from problematic power. UPS's rapidly switch to battery backup, so, they too protect your devices from the jarring "ON" - "OFF" cycles that happen when the power company is having or fixing problems.

Power Strips or Surge Suppressors

Why have power strips been left out of the discussion? The actual surge suppression capabilities of power strips are nearly useless in the real world. In this situation, you get what you pay for. Does an annual $50 auto insurance policy or $50 health insurance policy offer much useful protection? The same applies for $10 power strips. Power strips are very useful for turning things completely "OFF", to save both electricity and heat, and to protect devices from power problems while not in use. Use your power strips 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 those appliances when they are switched on.

Grounding Issues

In many second and third world countries, the neutral leg of the public utility's power lines is NOT grounded, or is only poorly grounded. This causes some microwave oven transformers to explode (!!), and damages some printers and other devices. When you first move into a house or an apartment, you would be wise to test whether the important key outlets in the building are actually grounded.

Grounding and polarity issues should be corrected only by qualified electricians. Many of the Mexican electricians we have met do not even have the equipment or knowledge to test for or correct these problems. If you are moving into a house or apartment, and have valuable equipment or appliances, it would be a good investment to call in a qualified electrician to check these issues before you plug everything in.

Protection and Prevention

To wrap up the entire discussion, the degree of protection you get will almost certainly depend on the quality of what you buy. If cost is no object, Sola, Tripp, Fluke and APC tend to make good quality components and are available here in Yucatan. If you are more cost-conscious, various Mexican and Chinese manufacturers are making decent-quality electrical power protection units, but their quality control on some units can be spotty. We have tested six individual Koblenz brand voltage stabilizers ($75 USD each), and one of the 6 actually boosted 120V up to a circuit-damaging 145VAC, ruining our $300 Mosquito Magnet trap and damaging a clothes dryer. The other five Koblenz brand voltage stabilizers worked fine for the last five years.

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 normally quality manufacturers, like APC, sell cheaper devices that don't work as advertised. In 45 years of monitoring and massaging power quality, we've had zero problems with Tripp, Fluke or older Sola devices.

Electricity has been treated very casually in the past in the Yucatan. Only ten years ago, it was hard to find an electrician who wasn't also a plumber. Electricity was not present in every house and electricians in Merida did not have the same rigorous education in electricity that many of us are used to expecting. To protect yourself and your appliances, it pays to find a good electrician (and you can these days...) and to invest in protective devices.

Especially when it comes to that mysterious element we call electricity, a modicum of prevention can save you a world of headaches.

Steven Fry writes for Yucatan Living when he isn't writing for his own blog, Yucalandia, for which we are very grateful.


  • Nell Graham 4 years ago

    I am having trouble finding the Tripp Lite suppressor for washer/dryer in the Cancun area. Does anyone have any suggestions where I might find one?

  • William 7 years ago

    I agree with you about trip and apc's quality, but what Im having a hard time figuring out are the lightning arresters. I saw some on trips website, but what type? who installs them? how much?

  • steven fry 7 years ago

    Hi Tom,
    Just how do you define low voltage? If you are talking about the USA â€œlow voltageâ€ standard ( < 90V or 49V), there is not much low voltage work available here: a few PV solar systems, some doorbells, etc. If you are talking about the UK/Australian/NZ et al "low voltage" standard ( < 1000 V ), then there is work available here.

    If you do typical 127V or 254V (aka â€œ220 Vâ€) work, then there is modest demand here, but know that you will be competing with very low-paid local electricians. In our personal experience, most expats from the USA and Canada come here expecting to pay low prices for things. If you charge much more than $100 pesos an hour, you may find that you have few customers.

    If you follow past discussions on Yolisto, US electricians have come here offering "US levels of service", but they have generally not found enough customers willing to pay for this expertise. When you wire things to US or Canadian standards, you may frequently find yourself priced "out of the market". Before a permanent move, many old-timers advise living here for a few months to check things out, to see if you enjoy the albiÃ±ile (masonry) work that is required as a part of being an electrician here. Electricians doing renovation work here need to saw, cut, chisel out channels into rock walls (mamposteria) to lay in cables, and then they patch the wall after installing the wiring. I would suggest that you come and see how things work here, and see if you like it.

  • Working Gringos 7 years ago

    Tom, it might be hard to find a job as an employee, but you might be able to find work as an independent contractor working for expats who are building homes. Good electricians are hard to find...

  • Tom Thomas 7 years ago

    I am a licensed low voltage electrician with experience in high voltage, alarms ect. My wife and I have really been considering moving to the Yucatan area. Do you have suggestions for questions regarding ex-pats finding work down there and if that field is promising??

  • Steven Fry 9 years ago

    Hi Rio,
    Your Koblenz RI-2502 is a special purpose voltage regulator, rated for 1500W to operate appliances with electric motors, like refrigerators, washing machines, and dryers.

    Because it is designed to support a bigger household electric motor, it only has one outlet on the back vs. other 1500W regulators with many outlets for operating computers, microwave ovens, stereos, etc.

    The issues around connecting your washing machine and your propane gas dryer depend on your particular washer and dryer. Some washing machines use only 500W, while others use 2000W. Some propane dryers use only 500W, while others use 1500W.

    CHECK THE WATTAGE or AMPERAGE of your washer and dryer before considering ganging both loads onto a power strip connected to your regulator. If the total wattage of the washer and dryer are below 1500W, then your idea should work OK.

    Note that electric motors draw 50% to 400% more power when starting, so it would not be good to push the start buttons on the washer and dryer simultaneously.

    Better still: Use a Kill-A-Watt meter to measure the actual power usage of your appliances to prove that the total wattage is lower than 1500W. I have a Kill a Watt meter, thanks to a good friend. Note that your specific Koblenz unit is known to have occasional problems (which show up right away), due to passing too-high of voltage (from the factory).

    If we met at Merida Mens Club or for coffee, I would be glad to check out the washer and dryer wattages, and test if your Koblenz regulator is working as promised.
    All the best,
    Steve Fry

  • Working Gringos 9 years ago

    Working Gringo suggests not doing that. It depends on wattage ratings. But just off the cuff, in general, not recommended!

  • Rio 9 years ago

    I have a Koblenz Ri-2502 voltage regulator with only 1 receptor in the back for plugging something in. I'm trying to find out if I can plug both my washer and dryer into a power strip and then plug the power strip into the voltage regulator. Any ideas?

  • Corinne Lopez 9 years ago

    Yeesh! Wish I had read this before two modems, the phone, and our dvd player got fried. Now to get the husband to read this article......

  • Dr. Fry 9 years ago

    Chedraui had 2 decent models, depending on how many watts (VxA) you need to supply. Electronica Gonzalez carries some Koblenz models, but I have seen some of theirs that do not reduce high voltage consistently. I have seen one Koblenz unit that actually increased line voltages to 145V. I have seen 4 that worked OK. Office Depot carries various models. Whatever model you buy, I would test it before keeping it or before putting it into service.

  • Steven John 9 years ago

    Good article. Where do you buy the Voltage Regulators in Merida? Will be moving soon to Progreso and would like to get one for my refrigerator.

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