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My house was built in the 50's and has a 2 wire system. Currently the outlet for my dryer is a 3 prong NEMA 10-30. Everything I read goes back and forth between it either okay to use since its already installed and that I run the risk of electrocution if the neutral wire gets damaged. So I have 2 questions:

  1. How much of a risk is there for the neutral wire to actually get comprised?

  2. If my house is a 2 wire system, is there a way I can retrofit a ground wire to the outlet so that I can install a 14-30 4 prong receptacle?

Edit: The wiring to the outlet is a 3 wire cable, 2 hot wires and one neutral.

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  • Is your wiring insulated? For the system now? In years past we did not put a neutral in there were 2 hots and a ground (bare copper). If this is what you have a new cable would need to be pulled. If all 3 are insulated you could pull a ground it no longer is required to be in the same cable to make this safer. There are millions of 3 wire ranges and dryers out there and you don't hear about electrocutions these would be big news like shark attacks because they don't happen very often. – Ed Beal Nov 27 '17 at 20:08
  • The cable has three insulated wires running to the outlet, 2 hot and a neutral. – soren thomsen Nov 27 '17 at 20:15
  • @EdBeal shocks from miswiring aren't news. A NEMA 10 failure is not miswiring, but the firemen and reporters don't know the difference, and report them as miswiring. – Harper - Reinstate Monica Nov 27 '17 at 22:06
  • @sorenthomsen then you're all set. Use any route that is practical back to the same panel that powers the dryer. Keep in mind other retrofit grounds can also share this ground path if the wire is big enough. You need #10. – Harper - Reinstate Monica Nov 27 '17 at 22:08
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Since you have 3 insulated conductors I would add an equipment ground conductor this is legal now. 3 wire systems are still legal and do not require update but it is a good idea to have a 4 wire system this is safer. Make sure the new ground is connected to the ground bus if this is coming from a sub panel and the neutral is on the neutral bus. If in a main panel they may go to the same bus as they are tied together.

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