Replacing 2 prong devices?

[DirtyLunka]

A friend just bought a house and one bedroom has 2 prong outlets and they want to replace them with 3 prong. The house is old and my concern is there is no ground(knob and tube or old bx). whats the best and safest solution to chande to new devices.

 

[Dennis Alwon]

A friend just bought a house and one bedroom has 2 prong outlets and they want to replace them with 3 prong. The house is old and my concern is there is no ground(knob and tube or old bx). whats the best and safest solution to chande to new devices.

Well you can
1) rewire with new nm cable
2) add a ground wire to each box and tie to the panel or the water pipe within 5' of where it enters the building, if it is an electrode
3) add a gfci receptacle and change all downstream devices to 3 prong. They must be marked with the sticker from the gfci box that states "No ground"

But then you should not be doing this work if you are an apprentice.

 

[Open Neutral]

Well you can

2) add a ground wire to each box and tie to the panel or the water pipe within 5' of where it enters the building, if it is an electrode
3) add a gfci receptacle and change all downstream devices to 3 prong. They must be marked with the sticker from the gfci box that states "No ground"

There are non-safety/NEC reasons for grounds. [RFI is one]
Would it be legal to do 3) and provide a non-AHJ conforming ground?

 

[Dennis Alwon]

Would it be legal to do 3) and provide a non-AHJ conforming ground?

I don't understand. You don't need a ground wire in the other devices and you still can use 3 wire recep., if they are fed thru a gfci device such as a breaker or receptacle.

 

[Open Neutral]

I don't understand. You don't need a ground wire in the other devices to meet Code and you still can use 3 wire recep., if they are fed thru a gfci device such as a breaker or receptacle.

As I said, there are non Code/safety reasons to ground things. One is to have metal cases grounded to absorb static zaps. Another is for RFI issues. Neither requires a code-legal ground.

 

[iwire]

There are non-safety/NEC reasons for grounds. [RFI is one]
Would it be legal to do 3) and provide a non-AHJ conforming ground?

In my opinion no.

That non-conforming ground could very well be a safety hazard if there was a branch circuit fault to it.

As a matter of fact you cannot even run a conforing ground.

406.4(2) Non?Grounding-Type Receptacles. Where attachment
to an equipment grounding conductor does not exist in the
receptacle enclosure, the installation shall comply with
(D)(2)(a), (D)(2)(b), or (D)(2)(c).

(a) A non?grounding-type receptacle(s) shall be permitted
to be replaced with another non?grounding-type receptacle(
s).

(b) A non?grounding-type receptacle(s) shall be permitted
to be replaced with a ground-fault circuit interrupter type
of receptacle(s). These receptacles shall be marked
?No Equipment Ground.? An equipment grounding conductor
shall not be connected from the ground-fault circuit interrupter-
type receptacle to any outlet supplied from the
ground-fault circuit-interrupter receptacle.

(c) A non?grounding-type receptacle(s) shall be permitted
to be replaced with a grounding-type receptacle(s)
where supplied through a ground-fault circuit interrupter.
Grounding-type receptacles supplied through the groundfault
circuit interrupter shall be marked ?GFCI Protected?
and ?No Equipment Ground.? An equipment grounding
conductor shall not be connected between the grounding type
receptacles.

 

[haskindm]

The armor of "Old BX" may be suitable as equipment ground. In that case, all you would need to do is bond the receptacle to the box, assuming the box is metal.