Is a weakly grounded 3-prong outlet dangerous?

Question

I recently moved into a house with 2-prong outlets in some locations and 3-prong outlets in the newer, renovated places. I checked all the outlets with a circuit tester and discovered that all the 3-prong outlets (except two) are properly grounded, and all the 2 prong outlets have "weakly" grounded boxes (the light on the circuit tester lights, but at a significantly lowered intensity compared to the hot. I opened the two 3-prong outlets that also showed "weak" grounding, and they are grounded to the electrical box via a s***w in the back. Those outlets are, however, GFCI outlets. This encouraged me to replace some 2-prong outlets with 3-prong outlets (non-GFCI) setup in the same manner, grounded to the receptacle box via a s***w in the back. As a result, they are grounded now, but only "weakly" using a circuit tester. Is this dangerous? I figured some ground is better than nothing. Also, i have surge protectors plugged into those outlets, perhaps adding a bit more safety?

Answer 1

Weakly grounded?  Is that like slightly dead?  It is either grounded or not.  Hire a pro

Answer 2

Very dangerous, your "weakly" grounded setup is no guarantee of a proper sufficient electrical ground.  Verify with a qualified professional electrician that your whole system is grounded properly and that each of the receptacles are also. He may be able to suggest a method of grounding the system properly, that is not to a water pipe.

Answer 3

If the metal box is not grounded you have no ground.  An ungrounded GFCI is safer than an standard 3 prong outlet, in that it should trip if the current flow in the neutral is not very close to the current flow in the hot.  You can run standard 3 prong outlets on the load side of a GFCI outlet without a ground provided they are label as such.

Find an electrician to get this straightened out for you.

Answer 4

The outlets you have changed to 3-prong outlets and 'grounded' to the boxes have done nothing to increase your safety level. The boxes of that age are not grounded so you have made a connection to nothing. If you are truly concerned about safety get an electrician to evaluate your system and install properly grounded outlets and inspect the currently installed gfci outlets for proper installation. Your efforts to increase the safety of your electrical system so far have been a waste of time.