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#### yojoe79

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Hi I am preparing for MY Red Seal Exam and I need some help with the conductor sizing for voltage drop. here is my question

What is the minimum size RW90XLPE conductor for a load drawing from a 20amp Double pole breaker (120/240) if the distance is 94m?

#### FrunkSlammer

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Where do you get stuck on this problem?

#### Next72969

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FrunkSlammer said:
Where do you get stuck on this problem?

#### yojoe79

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LOL I just don't get it I have been reading the info in table d3. So I started punching in values for different cable sizes until I get the distance required.

#### FrunkSlammer

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Use the equation they give you in Table D3:
Xdistance * 3(%) * 1.00 * 2(240v) = 94m
Xdistance = 15.66m

So now go to the D3 chart and you'll see for 20A that it falls between #8 (12.3m) and #6 (19.6m). Since it's not even close to the lower conductor, it must be the bigger conductor size.

That seems like a pretty clear cut one.. the trickier ones are where it's close to the smaller conductor size and you want to know if you can actually use the smaller conductor. Then you gotta crunch those correction factors.

#### Wirenuting

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I pretwist and then use wire nuts. Solder pots rule.
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yojoe79 said:
Hi I am preparing for MY Red Seal Exam and I need some help with the conductor sizing for voltage drop. here is my question What is the minimum size RW90XLPE conductor for a load drawing from a 20amp Double pole breaker (120/240) if the distance is 94m?

So your real question should sound more like,,,,, "Were would I look to figure out what sized conductor I need."

#### yojoe79

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so I came up with #8 which gives me

15.4 x 3(%) X 1.08 x 240/120 = 99.7m

The example under the Distance correction factor table is pretty straight forward but the amperages that they are using seems to be based on the values from the 2009 CEC before.

#### yojoe79

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So if you are given a current value of 13A the in table d3 you would choose the higher current vale which in this case would be the 16A Row. Am I correct in saying this?

#### FrunkSlammer

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Interpretation I guess, I don't interpret that a 20A breaker can or will only be loaded to 16A.

#### Laroc3

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FrunkSlammer said:
Interpretation I guess, I don't interpret that a 20A breaker can or will only be loaded to 16A.
Breakers at rated at 80%, that's why it will only carry 16 amps.

#### yojoe79

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Another thing is breakers are rated for 75 degrees so do I use the 75 or 90 column in table 2?

#### Laroc3

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yojoe79 said:
Another thing is breakers are rated for 75 degrees so do I use the 75 or 90 column in table 2?
You use what ever the conductor is rated for.

#### Aegis

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4-006 (1) for your 75 and 90 degrees

#### yojoe79

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so that basically says that if the equipment is marked for 75 then I have to use that column.

#### Aegis

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yojoe79 said:
so that basically says that if the equipment is marked for 75 then I have to use that column.
Yes. And then in 4-006 (2) , if it's not marked then use 90

#### yojoe79

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Thanks. Also if you are sizing conductors for motors I was told that you always have to use the 75 degree column unless its a class A motor

#### Aegis

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28-104 and Table 37 Is what you're looking for.

#### spinninwheels

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Thanks. Also if you are sizing conductors for motors I was told that you always have to use the 75 degree column unless its a class A motor
As Aegis noted, 28-104 is for motor supply conductors, which is the last section of wire to the motor. But where possible, the wire running to that last junction point (which is connected to the motor supply conductors) if 90C wire, can be taken from the 90C column.

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