A Discussion has been started about this Question. To view it or take part click on the View Discussion button below. By asking this question you are probably not quite ready to take on this particular task. You may or may not get lucky and receive some information in an answer here! If you hope to get enough information on this site to be able to do this job properly and safely, please do not rely on getting accurate information about such a potentially dangerous subject. Really, don't do this one yourself. Electricity is far too dangerous to handle if you have not been trained how to do this work. If you put just one wire in the wrong place you risk being killed by electrocution or you could even start a house fire.
How to do this job depends entirely on the Wiring Codes or Regulations for the locality (Town/State) and on the exact locations of the main service entry point and any outlets you wish to install. If they are anywhere subject to water splashes or spray - such as in any room supplied with running water pipes, like a kitchen, bathroom, shower room, etc., or in a pool-side area - in many places nowadays it is actually illegal to attempt to do this kind of work unless you are already a licensed electrician. If you don't want to go to your local library or bookstore - to find and read some books about electrical wiring and appliances and how to install them safely, and to find out about your local Wiring Codes and Regulations - then the best advice anyone should give to you is to call a licensed electrician either to do the job for you or to advise you what you may be allowed to do yourself. IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
If you do this work yourself, always turn off the power
at the breaker box/fuse panel BEFORE you attempt to do any work AND
always use an electrician's test meter having metal-tipped probes
(not a simple proximity voltage indicator)
to insure the circuit is, in fact, de-energized.
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Depends on the size of the service. 100 amp service will require 3 gauge, 150 amp service will require 1/0 gauge, and 200 amp service will require 3/0 gauge.
A 100 amp residential service requires a size #8 copper wire, it should be insulated in green.
For Service Entrance Cable 600 kcmill (Thousands of circular mils).
Look on the handle end of the main breaker. There should be a number there. That is the amperage of the main breaker. That is the size of your house service.
Yes, the wire size has to be increased. The existing 100 amp service will now probably have a #3 conductor with an insulation factor of 75 or 90 degrees C which is rated for 100 and 105 amps respectively. Increasing to a 150 amp service will use a #1/0 wire size. If you are thinking of an upgrade, skip the 150 amp service and go to a 200 amp panel. New homes are installing 200 amp 42 circuit panels. The extra cost is only reflected in the materials as the labour costs will be the same regardless whether a 150 amp or a 200 amp panel is installed. The wire size for a 200 amp panel is #3/0. With an insulation factor of 75 or 90 degrees C the rating is 200 or 210 amps respectively.