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#89614 10/10/04 07:34 AM
Joined: Jun 2004
Posts: 613
S
Member
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

2017 / 2014 NEC & Related Books and Study Guides
#89615 10/10/04 08:20 AM
Joined: Apr 2004
Posts: 201
Member
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


Charlie Eldridge, Indianapolis Utility Power Guy
#89616 10/10/04 11:12 AM
Joined: Jun 2004
Posts: 613
S
Member
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

#89617 10/10/04 11:27 AM
Joined: Aug 2002
Posts: 402
J
Member
Wouldn't the existing ground conductor be considered grandfather in? It met exisitng codes at time of install.

#89618 10/10/04 11:40 AM
Joined: Jun 2004
Posts: 206
C
Member
shortcircuit, If you are doing this in MA check 406.3(D)(3)(b). 250.130 (C) is not acceptable under MEC.

#89619 10/10/04 11:45 AM
Joined: Mar 2004
Posts: 785
B
Member
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.

#89620 10/10/04 12:38 PM
Joined: Apr 2004
Posts: 201
Member
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. [Linked Image]

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Charlie Eldridge, Indianapolis, Utility Power Guy


Charlie Eldridge, Indianapolis Utility Power Guy
#89621 10/12/04 12:43 AM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
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!


Mark Heller
"Well - I oughta....." -Jackie Gleason
#89622 10/12/04 01:14 AM
Joined: Sep 2002
Posts: 909
N
Member
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.

#89623 10/12/04 06:42 AM
Joined: Apr 2004
Posts: 201
Member
Quote
Table 250.122 has full size grounds for circuits 15 - 30A!
E57, I understand that, please read my first post and then my second post. [Linked Image]

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Charlie Eldridge, Indianapolis, Utility Power Guy


Charlie Eldridge, Indianapolis Utility Power Guy
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