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Adrian

Sep 30, 2005, 4:05 PM

Post #1 of 12 (10260 views)

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Electrical Supply Voltage - the CFE Responds!

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Due to my concern at the 140V found regularly on my wall outlets here in Tampico, and the fact that my nice new shiny coffee maker blew its element the other morning (well, it was only rated at 120V), I asked the CFE...

"Estimado Señores, what is the notional voltage and frequency supplied by your system and what is the permitted variation?"

They replied:
Buenos dias, gracias por contactarnos , referente a tu solicitud, te comento lo siguiente:

En conexion estrella la variacinon es de 127 a 220 Volts
En conexion delta v de 208 a 240 vollts.

ARTICULO 18.- El suministrador deberá ofrecer y mantener el servicio en forma de corriente alterna en una, dos o tres fases, a las tensiones alta, media o baja, disponibles en la zona de que se trate, observando lo siguiente:
I. Que la frecuencia sea de 60 Hertz, con una tolerancia de 0.8 por ciento en más o en menos, y
II. Que las tolerancias en el voltaje de alta, media o baja tensión no excedan de diez por ciento en más o en menos y tiendan a reducirse progresivamente

Simply put: The standard domestic electrical supply in Mexico can range from 114V to 140V and in frequency from 59.5Hz to 60.5Hz. This may imperil any electrical items from NOB that you bring as they are usually rated at substantially lower voltages.

Adrian

Marlene

Oct 1, 2005, 8:49 PM

Post #2 of 12 (10219 views)

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Re: [Adrian] Electrical Supply Voltage - the CFE Responds!

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Thanks Adrian. That is good information for folks to be aware of. I have gone through three microwave ovens and 3 computer hard drives since moving here 5 years ago. In Canada my microwave was over 15 years old when it died. We are certain that the electricity plays a major role in this early demise. We find too that living on the coastline is much harder on appliances, equipment, vehicles etc so not just the CFE is at the root of this problem.

raferguson

Oct 1, 2005, 11:08 PM

Post #3 of 12 (10215 views)

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Re: [Adrian] Electrical Supply Voltage - the CFE Responds!

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This is very interesting. The US spec, as I recall it, is 120V plus-minus 5%, but then they allow an additional 5% loss for distribution inside the house, so US equipment should be designed to run on 108V to 126V. But if the nominal voltage in Mexico is 127 volts instead of 120V, and they allow 10% over that, that would explain the high voltage that many people see, and problems that people see using US equipment in Mexico.

I ended up wiring up a buck transformer for my RV to take the voltage down about 12%, but I have not been RVing in Mexico since then, so I have not used it other than testing it in my driveway. One option to high voltage at the tap is your own transformer to reduce the voltage. This could be done for the whole house, or just for some equipment. You can also buy commercial voltage regulators, typically with 10 amp output. I would sure do something if my house voltage was 140V.

Richard

http://www.fergusonsculpture.com

Esteban

Oct 3, 2005, 8:18 AM

Post #4 of 12 (10190 views)

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Re: [Marlene] Electrical Supply Voltage - the CFE Responds!

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In Mazatlan, I have been having problems with LOW voltage. I'm working on a 14 ton AC chiller unit and when the voltage drops too low, the unit shuts down. If the volts drop, the amps increase and that is a problem. We are working at the low end of the limits but I think that during the night, the voltage drops below the limit and shuts down the unit. I'm hoping we can get CFE to adjust the transformer and bring the voltage up just a little. We are on three phase elec so it's possible to adjust it. It could also be the huge contactors inside the transformer are oxydized and need cleaning.

raferguson

Oct 3, 2005, 4:31 PM

Post #5 of 12 (10162 views)

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Re: [Esteban] Electrical Supply Voltage - the CFE Responds!

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I would expect that many large transformers, single phase or three phase, have multiple taps, to enable adjustment of the output voltage.

I am a bit surprised with low voltage at night. Normally the maximum current draw in warm climates is during the day, due to air conditioning. Maximum current draw usually means lower voltge, due to IR voltage drop. But perhaps air conditioning is not as ubiquitous in Mazatlan as north of the border, and the lighting load dominates.

Worst comes to worst, you could buy your own transformer, configured as a buck-boost, and solve the voltage problem yourself. You might need a real electrician, not the usual self-taught Mexican one, whose work scares me. Not sure how much it would cost, but it might not be as much as you think.

You can check the contactors by measuring the voltage drop across them under load, it should be a fraction of a volt.

Richard

http://www.fergusonsculpture.com

S & C

Oct 11, 2005, 1:57 PM

Post #6 of 12 (10111 views)

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Re: [raferguson] Electrical Supply Voltage - the CFE Responds!

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If your voltage varies to the point where you burn out equipment you might try buying a small voltage regulator. I have one we use on the refrigerator just in case and it trims or boosts the voltage to safe levels when needed.
Ours is by Tripp lite, the same people that make the UPS' and battery backups for computers. They have several models and have 4 to 6 receptacles on them. Be sure to buy the size you need. I have a 5 amp unit that works fine for the frig. You might be able to plug several small things into one unit. (In size it is about 5" square and they cost around $80 USD and up).
Stan

johanson / Moderator

Oct 11, 2005, 6:11 PM

Post #7 of 12 (10097 views)

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Re: [Adrian] Electrical Supply Voltage - the CFE Responds!

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Adrian, when you wrote, "II. Que las tolerancias en el voltaje de alta, media o baja tensión no excedan de diez por ciento en más o en menos y tiendan a reducirse progresivamente" I couldn't believe it. That seemed too great.

127 +/- 10% seemed too much. Today I ran across two CFE employees, they confirmed those figures. Considering the fact that 127 volts is standard, a 10% variance means,as you said,114 to 140 volts. 140 volts is very high for a US product, and would fry many products made only for the US or Canadian market

I have had refrigerators built in Mexico for Mexico that have worked 15 years without a problem without voltage protection. But then again the power supplies for these units are made for Mexican voltages. I would never use a product made for the US or Canadian voltages in Mexico without protection.

Oh correction, I did. It is in for repairs as we speak. Thanks for the SHOCKING information

(This post was edited by johanson on Oct 11, 2005, 8:56 PM)

Adrian

Oct 11, 2005, 8:27 PM

Post #8 of 12 (10085 views)

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Re: [johanson] Electrical Supply Voltage - the CFE Responds!

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Indeed, I thought the 10% variance was high - hence my contacting the CFE in the first place. The quote, incidentally, was a straight cut & paste from their response so there's no doubt over my poor Spanish!

We have switched to 130V regular incandescent bulbs and 127V compact fluorescents for lighting. Nearly all the appliances are Mexican market but I have a homebrew regulator supplying 127V steadily to the stereo, TV & DVD player.

Of course, my radio workshop is another matter - the bench power is regulated to the US standard 115V in deference to all the tube gear!

Adrian

Georgia

Dec 17, 2005, 7:14 AM

Post #9 of 12 (9977 views)

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Re: [johanson] Electrical - Voltage Corrrector

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After a lot of burned out MEXICAN products as well as American ones, we purchased a whole house voltage corrector. I still have the separate voltage regulators with battery backup on my computers. The correctors (actually we have two because we have two separate meters) were pricey, but the combined cost was not as much as one good appliance or pump. We have a pool with two separate pumps to protect (filter and swim-jet) plus all my husband's shop equipment on one meter and our house, casita, and caretaker's house on the other meter - so that's three refrigerators, computers, etc. to protect. Well worth it.

juditha16

Dec 20, 2005, 6:40 PM

Post #10 of 12 (9925 views)

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Re: [Georgia] Electrical - Voltage Corrrector

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Hola, Georgia,
Can you tell us more about the whole-house voltage regulators? Where did you buy them? from an electrician? Costoc? Are they difficult to install? What is the price range? Having one sounds like a good idea. Thanks.
Judith

johanson / Moderator

Dec 20, 2005, 6:54 PM

Post #11 of 12 (9918 views)

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Re: [juditha16] Electrical - Voltage Corrrector

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Before considering a whole house voltage regulator, I would want to know what my line voltage is in my home. For the past 8 years I have monitored my line voltage. I have never seen over 129 nor below 114 (once we had a brown out for three days with an average line voltage of about 90). So I do not need a whole house voltage regulator. I have friends in other neighborhoods who often have very high voltage where a whole house regulator would be a good idea.

And apparently in Joco where Georgia lives there are periods of very low voltage.

(This post was edited by johanson on Dec 20, 2005, 8:55 PM)

Georgia

Dec 20, 2005, 7:50 PM

Post #12 of 12 (9911 views)

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Re: [juditha16] Electrical - Voltage Corrrector

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We purchased our voltage corrector (which is the best protection against LOW voltage periods which really wreak havoc with electronics) through our pool installer. They are not cheap: about $800 installed. They are large. This is not a do it yourself project. We have problems of very low voltage in our village as well as surges, so we really felt this was the best solution instead of ten or so different units scattered around.