I want to upgrade the plugs to ground type in a house built in the 1960's.The old romex has a reduced size (#16 I think)grounding conductor in the cable that is wraped around the romex and pinched in the connector or under the clamp of the metal box.
What is the correct way to convert to ground type plugs in this case?
Is the reduced size ground wire in the romex OK to use for grounding?

shortcircuit

There is nothing wrong with the reduced size grounding conductors. The reason the grounding conductors were required to be made to match the circuit conductors in the smaller cables (#10, #12, and #14) is that too many DIYs and jacklegs were using the grounding conductors for circuit conductors. I have even seen the grounding conductor used as a phase conductor where a single-phase switch was converted to a three way without replacing the cable (they just taped up the grounding conductor and connected it to the switch and light fixture).

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Charlie Eldridge, Indianapolis, Utility Power Guy

Table 250.122 requires a #14 copper grounding conductor for a 15 amp overcurrent device protected circuit...so how can the #16 grounding conducter in the old romex be used for grounding when upgrading a house to grounded plugs?Is there an exception somewhere?

shortcircuit

Wouldn't the existing ground conductor be considered grandfather in? It met exisitng codes at time of install.

shortcircuit, If you are doing this in MA check 406.3(D)(3)(b). 250.130 (C) is not acceptable under MEC.

Charlie, I was taught the reason the grounding conductors size was increased was for fault clearing, that is, to prevent the grounding conductor from burning open before the OCPD opens.

BigB, the smaller wire works just fine for fault clearing the same as smaller wire works for fault clearing on larger circuits. Remember that the fault will be cleared before the current will destroy the grounding conductor or table 250.122 would not be valid.

Depending upon where you are working, you may or may not be "grandfathered". You need to check with your local laws and ordinances. In Indiana, you are permitted to continue to wire an addition with the Code that was in force when the home was built.

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Charlie Eldridge, Indianapolis, Utility Power Guy

Table 250.122 has full size grounds for circuits 15 - 30A!

15=14
20=12
30=10

But I too believe it should be OK as an existing installation. Just check with the AHJ, to be sure. If not, GFCI them!

If it met the code in effect at the time of installation shouldnt it be Grandfathered in?I was always under the impression that the code was not retroactive but, assuming things can cause lots of trouble.

E57, I understand that, please read my first post and then my second post.

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Charlie Eldridge, Indianapolis, Utility Power Guy

I don't think you will have any problems operating the overcurrent device with the down sized ground. I would just pigtail the grounding wire and get on with my life. It is all you have. Like another poster said, if you really think you will be losing sleep over it, put them on a GFCI. That downsized ground will certainly be enough to trip a GFCI.

Thanx for the replies...1st,I don't think the "grandfathered" rule would apply once I change the 2 prong style plugs to the currently used 3 prong style plugs since an upgrade is taking place with the installation of new grounded style recepticles.
But, I wasn't sure if the reduced size grounding wire in the old romex was acceptable for grounding when the code (250.122)specifies a #14 copper equipment ground to be used on 15 amp circuits.
Also at the main panel I'll have to unwrap the ground from under the metal romex clamp and connect it directly to the ground bar,as well as unwrapping the ground wire at each outlet box from under the box clamp and splicing them together and pigtail to the box and also to the device itself.Right?
Or can I just ground the device to the box and leave the grounds as they were originally installed in the 1960's?

You can but the Code did not permit the installation in that manner when it was installed (at least I don't think it did). Again IMHO, you are correct.

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Charlie Eldridge, Indianapolis, Utility Power Guy

Sorry Charlie, I spaced your first post.

No problem, I made a mistake just last year.

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Charlie Eldridge, Indianapolis, Utility Power Guy