Here's the problem I'm having. When our electric furnance (its really an oil/electric hybrid) kicks in, our lights dim and the UPS devices that are connected to my computers all jump into battery mode and don't come out until the furnace goes off. This usually means the computer shuts down first. Now, this doesn't happen every time, but enough to be a real annoyance.
The house was built in 1968, and has a 200 amp service from that era. Its also a Medallon home, for those familiar with houses in British Columbia from that time.
Now, any idea what is going on, or if there is an easy solution to this problem?
Measure the amperes carried by the furnace when it starts and and after it runs. You will need an ammeter with a peek hold feature. What size wire feeds the furnace and how far is the furnace from the panel?
Check connections at the panel for tightness.
Check connections at furnace.
After this, post your results here and we will get back to you.
If this is when the electric heaters kick in it could be a bad connection in the meter base, the main disconnect or even out in the utility equipment. You will probably need a meter to find this problem although if you really had a connection bad enough to cause this I suspect it would be cooking. (smell, sizzling, smoking). Do you have an AM radio? Is it full of static when this fails?
Your description is very suggestive of a failure in the connections of your service entry wiring. There are four sets of connections to check and only the utility can safely check three of them. The connections in your service equipment can be checked by an electrician who has the appropriate insulated tools. The first and cheapest thing to do is to call your electric utilities trouble number and explain that the furnace is causing other circuits in the house to go to a voltage low enough to trip the UPS into battery mode and keep it there while the furnace is running. Depending on there policies they may send a trouble man out to check your service drop or lateral and your meter base. Some will even check the service equipment connections because they are the only ones who can deenergize them under the public utility rules.
in article snipped-for-privacy@4ax.com, srewbigbrother at snipped-for-privacy@spamless.org wrote on 12/27/03 5:28 PM:
Does your house have aluminum conductors rather than copper?
It would be worth your while to get a decent digital voltmeter so that you could map out voltage in your house. Get a map before the problem shows. Map it after the problem shows. That could give a good clue where the voltage is dropping.
Actually, I already went through this process. I called BC Hydro and they sent a crew (two guys) out a few hours after I called. They disconnected the power outside, replaces something (I don't know what) and left. They never provided a report to me. But the problem continues. I'm suspecting it must be something inside the house. I'll likely call an electrician, since I don't know how to do the things already recommended here. Thanks all.
Another thing to check is the capacity of your service. I'd hope the BC hydro guys did this, but you may want to follow up with a call to them. How big is the transformer that feeds your house (may have a big number stamped on it like "12", "20", "50", etc)? How many houses is it serving? Have houses been built since your house was built that use this transformer, or have you or neighbors on this transformer increased their electrical load from when it was first installed (like changing from pure oil to oil/electric)?
My house was built in 1966 with a 200A panel. However, the transformer (which serves only me) was just a 10KVA unit because the house at the time only had about 80A worth of installed load. Additions by future owners increased my power demand calculation to nearly 200 amps, and I'm planning to go to well over 300A. Needless to say, the voltage dropped horribly when I turned on enough stuff to suck 100 amps. You should have a transformer rated for at least half the calculated amp value of your service (e.g. 200A service x 240V = 48KVA so you'd want a 24 KVA transformer assuming you really need all 200 amps of your service). I now have a 50 KVA transformer and larger wires from the transformer to my house.
I had a similar problem some years ago and detected it by measuring the voltage at the outlets when high current devices, such as electric heaters, were turned on. My normally 114 volts would drop to under 100. The connections were good. The next winter, during a rainstorm, the transformer on the pole blew and was replaced. That's when the problem disappeared. Obviously, if my connections were good, the transformer was either bad or undersized. A good amp clamp and a good digital volmeter should tell the story! Good Luck, Ross
If this is a recent developement it could be the furnace motor. If it is a capacator start motor a bad switch on the capacator will cause the motor to draw excessive current as it will not switch into the "induction run" mode.. The motor will run but sound different. The switch in such motor is usually a cheap POS and they fail after so many years ( besides the shaft it's the only moving thing in the motor). Also check the motor, fan and belt to see if there turning easily. You could have and obstruction that is loading the system ( bent fan, dead cat, etc.) and that will produce symptoms similar to what you have.
Well, I had an electrician come in this morning. He says its 100 amp service (even though his boss said it was 200 amp a couple years ago). He tightened everything up, we then switiched on the furnace, dryer, oven to see if we could "dim" the lights and trigger the UPS. No problems...no diming, and the UPS run without tripping. Max. draw was
60amps.
But he had a theory much like yours. He said to see if its worse from around 5pm to 9pm. He believes its the neigbours coming home and drawing more from the transformers. Sure enough, the UPS tripped in around 5pm briefly, and right out at 6pm when the furnance kicked in. I'll call BC Hydro again tomorrow.
Now, I'm also wondering if my neigbours would also notice the same things that I am...that their lights are dimming, etc. Or, if they have 200 amp service, they wouldn't notice?
Utilities do not have to follow the same rules as we in the private/public sector. I share a 20 kw transformer with my neighbor, both homes have 150 amp services. I doubt that I can produce a 60 amp draw on it even with my air conditioner (fla is 45 but it rarely pulls above 40). Voltage is another issue. Try to get them to raise the taps on the transformer, usually there are taps at 2.5% up and down. Or kindly ask them to record the voltage in your home for at least 48 hours. The IEEE states that they must hold the nominal voltage at plus 5% to minus
10% except for short periods of time. I think Canada follows the same specs, if not never mind. The utilities I have dealt with in the US, Canada and Mexico want happy customers if it is within the realm of possibility.
You appear to know a lot more about the utilities than I so I have a question for you. If the voltage is normal during low use periods wouldn't raising the taps cause it to be too high?..... Thanks, Ross
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