3

I just got results of home inspection on house I'm buying and discovered they had illegally replaced two prong outlets with three prong ones without correcting wiring. I understand my options may to rewire properly, install GFCI receptacles, either individually or at the beginning of each circuit, or install GFCI breakers in the panel. I understand that each outlet must have a sticker regarding grounding. But I hope and believe I'm wrong, that surge protector indicate that this is not acceptable method for the surge protector to properly work. If that is true, what other options are there to properly correct this problem? Should I cancel this purchase (which I can do based on the inspection results)?

I work from home and have computer equipment that needs to stay protected, especially since there are often storms and power outages.

  • When is the last time the house was sold? – Harper - Reinstate Monica Jun 28 '19 at 13:42
  • Harrper, Probably sold >15 years ago. Apparently bounced with different owners within a family due to divorce but doesn't appear tI have been on market anytime recently. I'm finding allot of houses with wonky issues that seem to correlate with DIYers that skip permits and common sense unfortunately. – EmmaSurf Jun 29 '19 at 11:33
  • Yeah that's typical, most DIYers (forum company excluded) tend to take the shortest possible path to "it works" and disregard codes and good sense. I was hoping the issue would've been taken care of on last sale. – Harper - Reinstate Monica Jun 29 '19 at 14:59
  • I am surprised that one answer was not discussed. That is go back to the seller and indicate to them that the sale is on only IF they repair the ground system to code! – Fred Suza Feb 7 at 19:29
  • Not sure whose surge protection guidelines you are following, but my understanding is most surges are produced outside the house, a surge suppressor at your electrical panel may provide your needed protection. – NoSparksPlease Feb 8 at 0:13
4

Grounded (aka 3-prong) receptacles without an actual ground path

Older houses did not have grounded receptacles. Simply replacing a 3-prong receptacle with a 2-prong receptacle provides a false sense of security - and can actually be more dangerous than leaving the 2-prong receptacles in place. There is nothing inherently wrong with a 2-prong receptacle. Many devices do not require a ground wire and come with a 2-prong plug. But devices that come with a 3-prong plug are designed to use that 3rd prong for safety and bypassing that is not a good idea.

There are 2 different solutions available:

Ground the Receptacle

This can be trivially easy or monumentally hard. It is trivially easy if the wires are run through metal conduit. Metal junction boxes connected to metal conduit all the way back to the panel generally provides a good grounding path. In other words, you connect a ground wire from the receptacle (typically attached to a green screw on the receptacle) or other device to a grounding screw. The grounding screw doesn't have to be green, but it does have to be the correct type in order to ensure a good connection.

If you don't have metal conduit then you can either retrofit a ground wire all by itself, which does not have to follow the same path as the other wires, or you can run a new cable, including ground, from the panel (which always has ground) to the receptacles. Running a new cable is typically easy in an unfinished basement or garage but much harder in the rest of the house.

GFCI

A GFCI, Ground Fault Circuit Interrupter, is designed to protect a specific type of problem, a ground fault. Despite the name, a GFCI does not actually use ground itself. Rather, it measures to see if current on hot(s) & neutral matches. If the current doesn't match then by definition it must be flowing through ground, and the GFCI breaks the circuit. So there is a class of problems where a GFCI or a good ground wire would provide protection, so GFCI is considered "good enough" to avoid the need to retrofit a ground wire. However, it does not protect against all modes of use of a ground wire. In particular, as you noted, there are surges and other problems which are resolved by making use of the ground wire and which won't be handled properly if the ground wire is missing. As a result, GFCI without an actual ground must be labelled to indicate there is no ground wire.

What to do?

I would recommend GFCI protection for the general usage receptacles. That is a cheap and easy fix. They do need to be installed properly in terms of Line/Load connections, or installed in the main panel (a little more expensive).

But for the most critical loads - i.e., your home office - retrofit ground if practical or run new circuits with ground. Unless this is a big house with "impossible" wiring and a full panel, adding a couple more circuits should not be that big a deal.

| improve this answer | |
  • 1
    Just makes clear how different different countries electrical systems are. "Older houses did not have grounded receptacles" - true in the UK too, but it's been so long since BS 1347 was introduced (1947), that the survey would have utterly condemned the entire wiring if the cables predated that. – Martin Bonner supports Monica Jun 28 '19 at 11:53
  • @MartinBonner Grounding requirements came in later in the US. But as I understand it, even really old K&T is still legal - no need to replace unless you have to upgrade for other reasons. – manassehkatz-Moving 2 Codidact Jun 28 '19 at 15:31
  • Martin, it's in the USA and even though it's definitely illegal, it depends on the jurisdiction how they seem to enforce compliance. Due to its and in mid 60's I thought 3 prong was standard, but not in this particular house. – EmmaSurf Jun 29 '19 at 11:42
  • 1
    This suggestion of a combo of GFCI for general use and grounding for specific room(s) will make this a safe house and keep the sale. I have to replace/upgrade the main panel anyway because they've overloaded it so could have GFCI breakers installed at that time. They have the whole kitchen on one circuit so that's gotta be fixed anyway There's access to a shallow crawl space so if I find a small electrician they should be able to access. Thank you for this suggestion. I understand theoretically the diff between grounding/GFCI but real life application was a tad more complicated. – EmmaSurf Jun 29 '19 at 12:02
1

GFCI protects humans, ground protects equipment

You are correct that GFCI will do little to protect equipment from surges. The only place the surge suppressor will have to dispose of surges is the neutral, which does at least go back to the neutral-ground equipotential bond in the panel. If that exists.

So for instance the path for a carpet-shuffle spark will be via the equipment case, the cable, the surge suppressor 's VBO between neutral and ground, neutral which leads right back to the equipment, then onward via wiring back to the neutral-ground equipotential bond in the panel. Not ideal.

Retrofitting ground is fine

As of NEC 2014, you need simply retrofit a ground wire from the ungrounded locations to the panel, grounding electrode system, or any other point with a thick enough ground wire back to the same panel.

| improve this answer | |
0

Most surge suppressors work with MOVs and need the ground wire to function properly. As you suspect, you can make the receptacle safe without an equipment ground by installing GFCI protection per the code prescription, but that will not help the surge protector function properly.

There are, however, surge protectors that work via other means, for example see brickwall.com - these surge protectors do not require equipment ground to function properly. With GFCI and a series mode surge protector, you'd have code compliance / safety and surge protection.

Of course you could add a ground to the ungrounded circuit, refeed it with new wiring, or add a new circuit for the sensitive equipment. In my opinion it would be too small an issue to cancel a sale over.

| improve this answer | |
  • Interesting re brickwall.com. Wasn't familiar with them. I could take with me when I go back to my real home so that's a plus. – EmmaSurf Jun 29 '19 at 12:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.