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04-01-2013, 05:55 PM   #1
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## a few basic questions?

hi,

i'm trying to become a bit more familiar with home electrical systems, i have a few questions i was hoping people could answer:

1.. so i'm under the impression that in canada, typical houses are on 100 amp, 150 amp or 200 amp 'systems' (not even sure if that's the right word). the higher the amps, the higher the current, and the more stuff you can run.

i'm in canada where i think everything is 120 volts or 240 volts, although i don't know why those particular amounts are what we use. in the electrical service panel, i have a number of breakers. each one of these breakers represents a circuit that is a certain number of amps. so for example i have a bunch of 15 and 20 amp breakers that run god knows what. each breaker represents 120 volts. appliances that require 240 volts use up two breakers and the little switches are usually tied together.

so for each circuit you would multiply the amps by the voltage to get the total number of watts you could put on each circuit? does that make sense? so like a 20 amp x 120 volts = 2400 watts.. i could plug in 40 60-watt bulbs on a single circuit without blowing anything? do i have that right?

my second question is that in my apartment there's an old electric stove/oven that has 8 fuses in it.. the fuses are in a line, and from left to right they read:

right front/right rear - 20 amp
left front/left rear 20 amp
oven - 20 amp
outlet amp - 15 amp
outlet amp - 15 amp
oven - 20 amp
left front/left read - 20 amp
right front/right rear - 20 amp

so first i don't understand why i have 2 of everything. and then it appears to me that with 150 amps in this single stove, shouldn't i have used up all/almost all the electricity in my panel (assuming a 150 or 200 amp panel?)

04-01-2013, 07:05 PM   #2
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Quote:
 Originally Posted by dsec123 hi, i'm trying to become a bit more familiar with home electrical systems, i have a few questions i was hoping people could answer: 1.. so i'm under the impression that in canada, typical houses are on 100 amp, 150 amp or 200 amp 'systems' (not even sure if that's the right word). the higher the amps, the higher the current, and the more stuff you can run....
Basically that is correct.

Quote:
 i'm in canada where i think everything is 120 volts or 240 volts, although i don't know why those particular amounts are what we use. in the electrical service panel, i have a number of breakers. each one of these breakers represents a circuit that is a certain number of amps. so for example i have a bunch of 15 and 20 amp breakers that run god knows what. each breaker represents 120 volts. appliances that require 240 volts use up two breakers and the little switches are usually tied together....
Again, mostly correct.

Quote:
 so for each circuit you would multiply the amps by the voltage to get the total number of watts you could put on each circuit? does that make sense? so like a 20 amp x 120 volts = 2400 watts.. i could plug in 40 60-watt bulbs on a single circuit without blowing anything? do i have that right?...
While mathematically correct, I would not recommend doing that.

Quote:
 my second question is that in my apartment there's an old electric stove/oven that has 8 fuses in it.. the fuses are in a line, and from left to right they read: right front/right rear - 20 amp left front/left rear 20 amp oven - 20 amp outlet amp - 15 amp outlet amp - 15 amp oven - 20 amp left front/left read - 20 amp right front/right rear - 20 amp so first i don't understand why i have 2 of everything. and then it appears to me that with 150 amps in this single stove, shouldn't i have used up all/almost all the electricity in my panel (assuming a 150 or 200 amp panel?) thanks in advance, i'm sure i'll have more questions as i learn about this stuff.
Those fuses are part of a sub-panel integral with the appliance. There are 2 fuses for each circuit, since those items are 240 Volt loads. One fuse for each 120-Volt line. You don't add the total value of all those fuses for a maximum rating. They are merely there for each sub-circuit's protection.

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 04-01-2013, 08:43 PM #3 Newbie   Join Date: Apr 2013 Location: Ottawa, Canada Posts: 28 Rewards Points: 58 thank you for clearing that up.. just to clarify (sorry if this sounds stupid or redundant), this 'sub-panel' is built within stove somewhere, correct? so my stove would have 4 circuits (left front/left rear, right front/right rear, oven, and outlet amp), and the fuses are to protect each circuit from the two sets of 110v pushing through them? if that's the case, would it even be possible to blow all the fuses on my stove? i mean if there are only 60 amps dedicated to stove (i'm not sure if that's correct, but i just read that 15, 20, 30 and 50 are common 'amp' sizes, so i'm guessing 30), how could i blow all the fuses? and if my stove is rated for 240v, and has 150 amps' worth of fuses in it, and my panel is supplying 240v at 60 amps or something, how would even one fuse blow? it's not like i can overload the circuit by plugging in 'extra' burners or something.. are the fuses only there just in case a wire melts or something really weird/accidental happens?

 04-01-2013, 09:13 PM #4 Electrical Contractor     Join Date: Sep 2008 Location: Delmarva Posts: 3,368 Rewards Points: 2,000 AS I said, you do not add up all the values of those fuses to obtain a rating of the appliance. Each fuse is intended to protect one part of the appliance's internal wiring. Those individual circuits most likely draw only a fraction of the fuse size amps, and as such those fuses are protecting the internal wiring against catastrophic failure. Most range circuits in the US today are rated for 40 or 50 Amps. Even a 12 kW range can operate satisfactorily on a 40 Amp circuit. Did you happen to blow all those fuses? Something like a direct lightning strike could do that, BTW. __________________ -KB Life is uncertain -- eat dessert first!!
 04-01-2013, 10:08 PM #5 Newbie   Join Date: Apr 2013 Location: Ottawa, Canada Posts: 28 Rewards Points: 58 hi kb, thanks again. i didn't blow all the fuses, just one of them.. which is what got me thinking about all of this. the front left burner stopped working, and when i replaced the one fuse that looked blown, it started working again. what i don't quite understand is that if the fuse that blew was for 'left front/left rear', why didn't both burners stop functioning? why did the rear left keep working? and then i was wondering how 20+ amps managed to go through that particular circuit when it's a stove with a burner.. it's not like you can plug anything 'extra' into that circuit. and if it was actually drawing a fraction of those 20 amps when used normally, what on earth would cause the fuse to blow? is there a reason the stove has fuses that are much much larger than what the stove is actually drawing? wouldn't a bunch of 2 amp fuses or something make a lot more sense? i mean if it takes something of the magnitude of a direct lightning strike to overload my stove, that seems a little ridiculous to me. when you say a 12 kW range can operate on a 40 amp circuit, is that because that particular range wouldn't actually really go to 12 kW unless you had ever burner and the stove and the lights turned on, and stuff plugged into the little outlet that's usually on the top somewhere... but if you did run that stove at full blast it would trip the fuse? (assuming you had a 40 amp fuse on a 40 amp circuit, which makes sense to me)..
 04-02-2013, 08:58 AM #6 Newbie   Join Date: Apr 2013 Location: Ottawa, Canada Posts: 28 Rewards Points: 58 still haven't been able to work this out just yet, can anyone help explain further?
04-02-2013, 09:52 AM   #7

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Was the amp rating on the fuse itself (the one that blew) the same as the other fuse protecting that circuit?
The stove is 240 volt and 120 volt. The manufacturer taps one of the two hot legs to drive the 120 volts to neutral features of the stove.

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Last edited by Stubbie; 04-02-2013 at 09:55 AM.

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