I'm looking for opinions to save me from codebook homework. The scenario is an old house wired with Romex and metal boxes. The romex has a gound that is undersized (#16 awg). The existing receptacles are worn out non-grounded type. The grounding conductors are twisted together inside the box and wrapped around the clamp screw. The owner does not want to rewire. Can the existing undersized grounds be used to attach new U-ground receptacles legally? It seems like a safer installation in one respect with the grounding but maybe a fire hazard due to the undersize ground. What about liability when you replace a ungrounded receptacle with a new ungrounded one? In the kitchen if replacing existing unground receptacles would it be mandatory (not just safer) to upgrade them to GFI? Old houses are cans of worms. Where do you draw the line with meeting current codes when doing repairs?
As long as the existing wiring is in good condition there I'm aware of no code requiring you to bring it to current standards when replacing devices. The undersized ground, if in good condition, should be OK. Check the continuity ground to neutral to see if it's good. You mentioned the grounds where twisted, you should crimp these. You are allowed to put 3 prong receptacles on an ungrounded system if you put the circuit on a GFCI, so if you want to be safe, do this for extra protection.
When replacing the outlets in wet areas like kitchens and baths always replace with a GFCI.
#94200 - 07/17/0509:43 AMRe: replacing old receptacles
i wonder if the home owner has a computer and other expensive electronic equipment that he would like to see knocked out by a spike or lighting strike. surge surpressors without a efficient ground are useless. perhaps instead of rewiring eveything a couple of new dedicated circuits would be worth the cost. in my humble opinion.
#94203 - 07/19/0506:02 AMRe: replacing old receptacles
wewire2 Valid point on the where do you stop bringing up to code. Insuring that no one gets shock and no fires would be main concern. Some codes are for convenience only and just make life easier. 406.3 (D)(1) If a grounding conductor EXISTS in the receptacle enclosure than a grounding type recept. SHALL be used. I agree with everyone on checking continuity of EG and tap from existing grounds. Plus the code requires the use of them if they exist in the enclosure. I would consider using some arc faults on the bedroom circuits and gfci in kitchen and baths.