slcpd6469
join:2003-09-25
Saint Louis, MO
| Tripped Main Breaker
I woke up this morning to my UPSs screaming that the power was out. I looked at my neighbors, they all had power. I checked the breaker box and the only breaker that was tripped was the 100 amp main. Before I reset it I checked for water around the box(off and on rain for 3 days or so) and also checked the meter and drop. I didn't see anything unusual so I turned it on and everything seems fine. The only thing I can think of is both furnaces and fridge kicked on at the same time. Other than that I'm stumped. Anyone have any other ideas as to what happened.
Background:
I just purchased this house 2 weeks ago and have had no electric issues until now. This is a 105 yr old house but all wiring,breaker box and meter have been upgraded. I have 1 elec furnace(2 weeks old) for upstairs and gas(unknown age) for downstairs. The only other items on were a fridge, small lcd tv, computer and a few other small devices. I'm thinking before summer comes I'll have to upgrade to 200amp service so I can run 2 ac units, fridge and everthing else. |
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dark_star
join:2003-11-14
| Is the breaker box inside or outside? If it is outside and unlocked, perhaps it was turned off by a prankster.
How many amps does the new electric furnace draw?
You could also try recreating the circumstances that may have resulted in the breakers tripping. Let the house get cool. Then turn on every small item that was on at the time it tripped plus a few more. Then turn the thermostats up on both furnaces simultaneously.
The results should rule out or confirm the possibility that your 100 amp service is not adequate to start both furnaces at the same time. |
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slcpd6469
join:2003-09-25
Saint Louis, MO
| The breaker is in a locked basement. The new furnace has a 60 amp breaker built into itself. None of the breakers in the box are labeled so I didn't know what size it is in there. I'll have to see if there are any stickers on the unit for power requirements. I'll also try and recreate it tonight. |
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mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
clubs:
 ·Mediacom
| reply to slcpd6469
Please post pictures if possible of the breaker panel. I suspect it may be brand or model that has been known to have issues, and the pros here can look and see if it is. Zinsco is one notoriously bad panel, and the one I used to have would trip the main due to excessive resistance and heat build-up where the main attaches to the panel. |
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nunya
SEE ROCK CITY 475 MILES
Premium,MVM
join:2000-12-23
O Fallon, MO
clubs: | reply to slcpd6469
Electric furnace + 100 Amp service usually = Bad.
Most likely the service is overloaded and the breaker is just doing it's job.
--
Looks like Reverend Wright got his wish - God Damn America. |
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scooper
join:2000-07-11
Youngsville, NC
1 edit | reply to slcpd6469
You need to do the service upgrade to 200 AMPs NOW if you plan on using that furnace. And even then - plan on thermostat on 60 and/or large electric bill. Said service upgrade is NOT a DIY job unless you are a qualified pro.
It would have been better to upgrade the gas furnace to handle everything, but that's in the past now. |
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whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
·Earthlink Cable Mo..
2 edits | reply to slcpd6469
The inrush from any devices in a house is not going to be the cause of a breaker trip. Inrush, which lasts less than one second does not trip thermal-magnetic breakers like the one you have. To boot, aside from the fan motor, your electric furnace shouldn't have any inrush (unless its an arc-furnace - unlikely). Thermal-magnetic breakers trip for two reasons - short circuit or overload.
Many people question whether they need to upgrade their service. My answer always is, has your main breaker been tripping. If not, then typically one doesn't need to upgrade their service. In your case, your main breaker tripped for one reason - overload.
Unless you have very little else in the way of electric appliances in your home, a 100A service is inadequate for the electric furnace. (Check the ratings - 60A is the size of the main breaker, but not the sustained current draw of the furnace.) There is no doubt that you need a service upgrade to handle your electric use with the electric furnace. Whether that upgrade is to a 150A or 200A service can only be determined via proper demand load calculations, which should be done by a qualified electrician or engineer.
My guess is that it was a home improvement contractor or HVAC contractor that installed the furnace. Every residential electrician I know (except the few that post here) would be jumping at the chance to sell you a service upgrade, whether or not you needed it. (And you do need it.)
One thing you should also know, is that the main breaker in your home is only rated for 80% (80A) of continuous load, although it will not trip until 100A of load is exceeded, and then only trip on a 'pro-rated' basis. In other words, it will trip a lot faster at 120A of load, then it will at 100A of load. Get some proper calculations done. Chances are great you need to spend a 'few' bucks for the service upgrade. |
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slcpd6469
join:2003-09-25
Saint Louis, MO
| reply to slcpd6469
I looked at the box and its not a Zinsco but I don't remember the name. I have a call into an electrician so hopefully he can point me in the right direction. I knew at some point I was going to need the upgrade but I was hoping to hold off til early next year. |
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scooper
join:2000-07-11
Youngsville, NC | I suppose there is one way you could put it off - just don't use the electric furnace. But whizkid has given you the best advice so far. |
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jack b
Gone Fishing
Premium,MVM
join:2000-09-08
Cape Cod
clubs:
·Comcast
| reply to slcpd6469
As already identified, the electric service entrance is likely inadequate at this stage of the game. An ammeter will help to tell you if it's an overload or faulty main causing the trip.
It could be the load is unbalanced? One leg probably has a higher load and operates near the main's limit where it can heat up enough to trip over time. To buy some time, maybe you could swap some circuits around to balance things a little better until you can replace the panel.
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slcpd6469
join:2003-09-25
Saint Louis, MO
| reply to slcpd6469
I know I need a service upgrade but this morning I unknowingly performed a test. Last night I had turned the downstairs furnace off and forgot to turn it back on. This morning at 5:15 when the upstairs unit kicked on the main tripped. The only items on at the time were 1 fridge, 1 lcd tv, 1 pc, 1 cfl bulb and 2 dtv stbs. With this test does it still sound like too much draw or that something is wrong with the upstairs furnace? The only times it has tripped are at 5:15 in the morning when the upstairs unit starts. BTW the electrician should be calling today as I realize this is not a diy job. |
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scooper
join:2000-07-11
Youngsville, NC | Yep - sounds like you unwittingly did another test, and proved again that you need a service upgrade.
BTW - until said service upgrade is complete - I'd secure the electric hog and only run the downstairs furnace. |
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cowspotter
join:2000-09-11
Ashburn, VA | Didn't you say that the downstairs (that was off last night) was gas and the upstairs is electric? If so, then you leaving the gas furnace off didn't really do much to change your electricity demand. The electric heat was still on. |
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slcpd6469
join:2003-09-25
Saint Louis, MO
| I forgot to add this, the elec furnace runs all day and night just fine. The only time it will trip is at 5:15am when overall usage should be lower. I have not had it trip say mid day when multiple tvs are on along with lights, washing machine and every other everyday item. |
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scooper
join:2000-07-11
Youngsville, NC | You still need to have an electrician look at this anyway. Main Breakers tripping off at a set time is not good either. Like I said - I'd power off the electric furnace until you get a clean bill of health after an electrician inspects. |
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scooper
join:2000-07-11
Youngsville, NC
1 edit | reply to slcpd6469
Is it possible someone is firing up a coffee maker at 0515 AM ? Or other "small electric appliances" (toaster, microwave, oven / stove) ? |
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jack b
Gone Fishing
Premium,MVM
join:2000-09-08
Cape Cod
clubs:
·Comcast
| reply to slcpd6469
Do you have a setback thermostat for this electric furnace?
Ill bet it could be the furnace has a multi-stage heater element and comes on at full power if the temperature is more than a few degrees lower than the set-point, then it continues to run on a reduced input power once the room temperature is closer to the set-point and while maintaining a fixed temperature.
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~Help Find a Cure for Cancer~
~Proud Member of Team Discovery ~ |
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scooper
join:2000-07-11
Youngsville, NC
| said by jack b  :Do you have a setback thermostat for this electric furnace? Ill bet it could be the furnace has a multi-stage heater element and comes on at full power if the temperature is more than a few degrees lower than the set-point, then it continues to run on a reduced input power once the room temperature is closer to the set-point and while maintaining a fixed temperature. Still needs a qualified electrician have a look. The OP should not be popping the main breaker on a regular basis. |
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JimmySask
join:2004-06-24
Regina, SK | reply to slcpd6469
If it is an electronic thermostat, is it set to keep the house at a cooler temperature overnight? If so, what time is it set to begin warming the house again?
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I do whatever my Rice Krispies tell me too.... |
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slcpd6469
join:2003-09-25
Saint Louis, MO
| It is a electroic thermostat. Its set to let the temp get down to 67 overnight then warm up to 72 starting at 5:15. The multistage element makes sense since it only trips in the morning. I dont know if this is the case as the unit was installed before I moved in. I will have to find a model number and research it. I am keeping the unit off until a professional can look at it. |
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