DETAILS OF PROBLEM IN COSTA RICA

[morham]

Because of the primitive nature of Costa Rican electrician?s wiring (use a ?mother line? down the center of the house and splice off that for all circuits) we decided to wire our own house. We used Rex Cauldwell?s book, Wiring a House, to proceed.

Our system begins at the street meter box where 240 comes onto the property through #6 Aluminum wiring (the standard for the electric co here). It is grounded at this site and has a porcelain knife switch for shut off to the service line. From here on all of our wiring is North American copper wire.

We then buried #4 in PVC electrical tubing and brought 3 wires ( 2 hots and a ground) to our work shop; a distance of about 70 feet.. Here we established another porcelain knife switch (100amp 250v) for the incoming line.

Here the line is split. One set of #6 wires (2 hots and a ground) goes underground in PVC electrical tubing to the house and its breaker box ( distance 30ft). Another set of wires goes from the same knife switch to the shop breaker box. Neither breaker box has an internal main switch.

The house has a Siemans 200AMP 24 space breaker box which is grounded at the house. The shop has a Cutler Hammer 200AMP 6 space breaker box that is not grounded at that point.

The house breaker box is wired as follows:
black(hot) to the breaker
white & copper to neutral/ground bus
Tie bar is in place connecting neutral bar and bus bar
Neutral and ground are grounded outside with a ground rod
panel bond is in place.
I can send a picture if it would help.

The wiring to the house is new this year. In years past our normal kilowatt usage has run about 200 kilowatts per month. This is running several machines on 220 lines from the shop (planers, table saws etc). Since the new wiring in the house and the addition of an electric stove and dryer we are now averaging about 800 kilowatts a month.

The questions I have for the experts are:
1)is our house breaker box wired correctly
2) Because there is a ground at the street does the indoor load center need to be grounded as well.
3) All of the high kilowatt usage is from the 220 lines (when the dryer is running it takes 1.5 sec for a revolution of the meter disc) Why?
4) Is the house load center considered a sub-panel even though it does NOT pass through the panel in the shop?

If any of you kind people have any information it would be greatly appreciated here, and as there are NO qualified electricians in the area I am throwing myself at your mercy. Please keep it simple!

 

[bennie]

Re: DETAILS OF PROBLEM IN COSTA RICA

First the good news... There is no violations of the NEC.

Now the bad news... Only due to the NEC not being adopted in Costa Rica.

The increase in power use, is due to the increase in connected load, and duration of operation.

My electric bill shows 2000 kilo-watt hours for last month. I would love to have 800 KWH.

There appears to be an issue with wire size and lack of short circuit protection on the feeders.

 

[morham]

Re: DETAILS OF PROBLEM IN COSTA RICA

Troubleshooting
Since the high kilowatt readings we have done the following:
1) shut off all knife switches to shop and house, and then checked the meter disc. No movement
2)turned on each knife switch with all breakers in breaker boxes turned off- no movement of meter disc
3) unplugged every electrical appliance and unscrewed every lightbulb.
4) opened and closed each circuit breaker (one at a time) to check for shorts- no movement of meter disc
5) pluggged electrical appliances back in and checked each circuit for speed of meter disc- each 220 circuit sped the meter disc up to about 2 seconds per revolution.
6)The electric company has changed our meter- no change in performance.

 

[stamcon]

Re: DETAILS OF PROBLEM IN COSTA RICA

Morham, what are the wattage ratings for these appliances(stove, dryer, shop equipment)? These are all high current drawing appliances and the meter's rpm spin rate will increase with the increase of load placed on the system.

 

[morham]

Re: DETAILS OF PROBLEM IN COSTA RICA

The kilowat hour ratings for various appliances are:

Dyer 5 KWH 4750 AMPS
Convection Oven- 1 KWH to maintain 450 F temp.

If my rudimentary calculations are correct, the dryer is using about 40KW per hour and the convection oven a little less.
(the meter takes 1.5 seconds for one revolution for the dryer. If a KW is equal to 139 revolutions of the meter, then every 92 second we are using one kilowatt)

The power tools in the shop have never caused us a problem We have been using those over the past three years and the consumption has always been less than 200 KW per month.

The things we are wondering about are:
1) the #6 wire from the shop to the house,(although we have checked with a volt meter and are getting 226 at each breaker in the house). Is it heavy enough?
2) the gauge wire from the breaker box to the appliance. We are using Romex 12/2. Is that heavy enough?
3) Could we be sending electricity to ground somehow?

While I agree that 800 KW is not a lot by North American standards. It is here! We do not have hot water heaters, furnaces, dishwashers and many other conveniences common in those homes. By in large the things being used here, other than the 220 items in question, are refrigerators, fans and lights. And, we use the dryer in the day when most of these items are off.

 

[dereckbc]

Re: DETAILS OF PROBLEM IN COSTA RICA

Morham, your numbers do not make any since. Example: A 5 KW dryer is 4750 amps. If the voltage is 220 to the dryer, the amps should be around 23. A convection oven will require more than 1 KW, usually 8 to 11 KW.

To answer your questions, more info is needed.

1. The #6 wire from the shop to the house, (although we have checked with a volt meter and are getting 226 at each breaker in the house). Is it heavy enough?

Cannot answer. What is the size of the breaker or fuse? The wire size is dependant on the over current device and not the voltage.

2. The gauge wire from the breaker box to the appliance. We are using Romex 12/2. Is that heavy enough?

Cannot answer, same as 1.

3. Could we be sending electricity to ground somehow?

Yes, if you have grounded your neutral downstream from the service, but it has nothing to do with your kilowatt usage unless you grounded a hot conductor.

Try this. If the dryer is 5 KW, it should register 1 KWH in 12 minutes. I will assume the oven is 8 KW. So the oven should register 1 KWH in 7.5 minutes. Determine what the actual KW rating is for each appliance, use this formula to determine how long it will take to use a KWH: 60 minutes/KW = time in minutes to register 1 KWH

[ March 17, 2003, 01:25 PM: Message edited by: dereckbc ]

 

[morham]

Re: DETAILS OF PROBLEM IN COSTA RICA

[Okay let me make another stab at this. the ratings for the stove appear to be 9 Kw, the dryer 5Kw. That makes more sense. So using your method, dereckbc, the kilowat hours should be 12 for the dryer and about 7 for the stove.
I checked the meter with the dryer running and we are consuming 1KW every 92 seconds from the house. We then carried the dryer to the shop, plugged it into a 220 circuit there, and the meter turns at the appropriate 12 minutes for 1KW.

The incoming power to the house from the shop is #6 and goes to a 200Amp load center. The breakers to the items in question; the stove and the dryer are both 30AMP double pole 220 breakers.

Our system is grounded in two places, once at the service entrance, and once at the home load center. It is grounded at the neutral/bus.I have looked at our center and cannot see that there are any grounded black (hot) wires.

We just disconnected the ground in the home load center and turned the dryer on- 92 sec for 1 KW.

Any ideas as to what is going on here? Clearly it is in the house, as our kilowatt consumption from the shop has always been appropriate, and our demonstration of the dryer today seems to indicate the same. Hope you all can help.

 

[dereckbc]

Re: DETAILS OF PROBLEM IN COSTA RICA

morham, ground is not the problem.

Although this is not your KWH problem, but a # 6 AWG feeding a 200 amp panel is a real fire issue. # 6 AWG is only good for about 55 to 65 amps. Should be more like a 2/0 copper for a service entrance, or 3/0 copper for a feeder. Your 30 amp branch circuits should be a # 10 AWG.

Without seeing the installation, sounds like a meter problem. Do you have a 3-wire service (P-N-P)? You should mearsure 110 volts between either phase and neutral, and 220 volts between the two phases.

[ March 17, 2003, 04:41 PM: Message edited by: dereckbc ]

 

[booch]

Re: DETAILS OF PROBLEM IN COSTA RICA

Morham,

From the start you need some safety devices. Fusable disconnect for each switch. (They are called safety switches)I can't stress that enough. no matter what their rules are you need to protect yourself.

Secondarily get yourself an amp meter as well as a volt meter if you don't have one. A clamp on type ampmeter as you seem to have to rely upon yourself for all the diagnostics. This counting the meter revolutions is certainly functional but it detracts from the job at hand. It is a distraction and as you'll see it is inaccurate.

You need to read real carefully the words written in these discussions. I put a post to you in Breaktime related to "Short circuit withstand ratings" The only reason I gave you that was to illustrate the need for the safety switch fusing. Withstand ratings are the largest abberation of power the wire can WITHSTAND without causing perminent damage to the wire or the insulation.

The above is vastly greater than the everyday load of a household circuit. The everyday load is based on the type of insulation on the wire. That again is larger than the wire should be fused/protected with a breaker.

14 Ga should be on a 15 Amp circuit max
12 Ga should be on a 20 Amp max ...
4 Ga should be on a 100 Amp feed ...

The fact that you have a 6 GA feed means you have a lot of resistance in the incoming feed from the utility.
When you fire up the whole house the meter runs fast (I'd bet) due to the fact that your 266 v (again you haven't given any of us the measurements if it is leg to leg or leg to ground) I assume Leg to leg voltage drops like a rock to 150 or less volts leg to leg. Consequently the amperage has to increase. Meter may say it measures KVA but I'd bet it has a voltage tolerance of +or- 15 percent from the installed circuit. When the voltage exceeds design limits the value the meter presents is (as they say in France "merde")

I sell many many parts to the world market for OEM's. They go to China, Indoniesa, India, Europe and the former eastern block. I gotta tell you beyond the financial and political strength of the US we also have the most reliable power grid in the world.

The developing world has few controls on the power delivered. The country utility may say 50 or 60 HZ @ X voltage but the plus or minus is remarkable. In many of the far flung spots I strive to hook up the manufacturers I support with voltage monitors. Run a 100 hp motor on 480 +- 10 % and it will run as designed. Run it 20% less voltage and the power isn't there and the windings are abused for the incompatable volt to freq ratio.

So,.. Get some readings of volts and amps with meter readings not the meter in the socket. In fact stick the VOM meter probes in the wall socket and just watch the voltage during the course of the day. (from first dawn to everyone at work will be the biggest variation in voltage.)

 

[hurk27]

Re: DETAILS OF PROBLEM IN COSTA RICA

morham If you are useing a lot of lights then there are bulbs that can drop the bill and it would take som caculating to figure it out as to how much. incandlesent waste wattage and there is some flouresents that will run on 220 but they will be costly in the beginning to purchase.

 

[morham]

Re: DETAILS OF PROBLEM IN COSTA RICA

Good morning
we have done some initial readings this morning.

with the dryer OFF
power at the main -leg to leg 243V
black wire(hot) 1.40 AMP
white wire(hot) 0.70 AMP
common 0.73 AMP

power at the main with the dryer ON:

power at the main- leg to leg- 238 V
black wire(hot) 10.98 AMP
white wire(hot) 8.98 AMP
common 3.00 AMP

Dryer and Oven on:

power at the main-leg to leg 241V
white(hot) 13.75AMP
black(hot) 14.95 AMP
common 2.33AMP

The only other items in use are a refrigerator, TV, lights and 3 ceiling fans.
The dryer and oven are currently wired using Romex 12/2, and the length of the lines is about 30ft each.
I also did a calculation of our load using Rex Cauldwell?s book, Wiring a House. We do not exceed 60Amps for the entire house, by my calculations. We do NOT have things like most North American houses; dishwashers, hot water heaters, furnaces, air conditioners, etc. We used a 200AMP load center simply for ease of wiring, and fewer crowded circuits.
Hope that you can find some information here that will help us solve our high kilowatt problem; she still takes off like a rabbit when the dryer or the stove is turned on.

 

[bennie]

Re: DETAILS OF PROBLEM IN COSTA RICA

The line voltage is higher than normal. This will use more power.

 

[hurk27]

Re: DETAILS OF PROBLEM IN COSTA RICA

Sound like the meter is a 15 amp or 30 amp if it is "taking off" as he said but it does sound like mabe the meter is not designed for the service and could be missed hooked up. here in the states hot's would be any color other than green or white the neutral/ commoned would be white and ground would be green. still not shure on how this service is hooked up but somthing does not sound right the current on the dryer moter is right at 3 amps but the heating elemints sound low unless this is a small dryer. the oven also seems low as a drier here will pull about 25/27 amps and a oven can pull as high as 28 amps?

 

[morham]

Re: DETAILS OF PROBLEM IN COSTA RICA

3/18 at about 11:30 AM

Voltage readings on startup
stove alone:
leg to leg @main 246V
startup 5.0amps running 4.50

Dryer alone:
leg to leg @main 241V
startup 11amps running 10.62amps

dryer and stove together
leg to leg@main 245V
startup 15.95 amps running 14.55amps

dryer stove and waterpump together
leg to leg@main 239V
startup 15.55amps running 14.60amps

These readings are with the refrigerator, fans on in the house, and a sander and the waterpump (220V) being used at the shop.

We did some random readings through the day, and they did not vary by more than a few hundredths in amperage, and the voltage never dropped below 230V. We stuck a VOM in an outlet and watched the readings over the day and they always read ~126V

Addressing the meter issue that hurk27 asks about, our meter at the street is a GE: CL100 240V AP15 60Hz kh 3.6

I know it is frustrating for all of you who are used to NEC standards to discuss this system, but it?s what it is, as the colors we used are what is available here in CR

The service entrance has two hots and a common(#6 AWG)from the meter to our knife switch(100AMP 250V/ with fuses) the hots are on the outside the common in the middle on both items.

There are Two hots and a common (#4AWG) coming from the meter to our shop knife switch (100amp 250v/with fuses) and
two hots and a common (#6AWG) coming from the shop to the home load center. The system is grounded in two places- once at the meter and once at the house load center off the neutral/bus.

So what is the general opinion about our meter and it?s capacity and I wonder about the #6 aluminum wire that delivers from the transformer at the street to our meter? Any comments would be appreciated.