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Mike G.
Mike G., Master Electrician
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Experience:  Proven Professional 48 years Experience
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Electrical
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What Size Aluminum And Copper Wires In A 200 AMP Box?

In a 200 AMP box... Show More

In a 200 AMP box, what gauge aluminum wire and what gauge copper wire is needed, the wire that feeds the panel?

I need info on the Copper wire as I was told to use it as it carries more current but I need the gauge size?

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Is this a residential or a commercial installation?

Customer reply replied 5 years ago.
It is for residential ....

4/0 Aluminum or 2/0 copper for 200 Amps.

Table 310.15(B)(7) conductor types and sizes for 120/240-Volt, 3-Wire, Single-Phase dwelling services and feeders. Conductor types RHH, RHW, RHW-2, THHN, THHW, THW, THW-2, THWN, THWN-2, XHHW, XHHW-2, SE, USE, USE-2

Conductor (AWG or kcmil):

Service or Feeder Rating (Amperes)
Copper
Aluminum or Copper-Clad Aluminum
100
4
2
110
3
1
125
2
Jan-00
150
1
Feb-00
175
Jan-00
Mar-00
200
Feb-00
Apr-00
225
Mar-00
250
250
Apr-00
300
300
250
350
350
350
500
400
400
600
Customer reply replied 5 years ago.

My existing electrical box is currently 100 AMPS, the wire that feeds the box is smaller than 2/0 but is copper. If I put in 200 Amps panel box and use the same amount of breakers and not change anything (I know it is not suppose to be legal).

What if anything were to happen?

Would there be a problem or danger?

What are your thoughts on this?

The total protection for the service is provided by the over current device. Even though the main breaker is after the service riser, it will not allow a higher amperage on the riser than the wire is sized for.

Your assumption that by using the same number of circuits that the 100 Amp service has means that there will never be a load more than the 100 Amps is a gamble. If there was the breaker would not trip before the wire burned.

Don't do it!

I thought of a way for you to keep the old riser and a new 200 Amp panel.

Siemens makes a main lug panel that can be converted to a main breaker. Install a 2 pole 100 amp breaker in the first opposition and use that as a main fed by the existing riser. This will meet code and at a later date you can install a 200 Amp main when you change the riser. Riser is the cable that runs up to the point of attachment.

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