Rehabbing, but rewiring? - Posted by Tony (CA)

Posted by Ron (MD) on June 26, 2001 at 16:35:00:


Unlike Jim Locker, who posted above, I don’t have an MS in Physics (nor do I remember much from the Physics course I took in high school 35 years ago). He sounds like a very smart guy.

All I can tell you is what I’ve been told by two separate licensed electricians and one city electric inspector. That is, if you have an outlet that doesn’t have a ground wire, you have two choices that conform to code. You can put in a two-pronged receptacle or a GFCI. The GFCI doesn’t actually ground the outlet, but my understanding is that it acts like a mini-circuit breaker to protect a computer, tv, etc. That’s all I know about it.

Ron Guy

Rehabbing, but rewiring? - Posted by Tony (CA)

Posted by Tony (CA) on June 25, 2001 at 14:20:00:

I’m starting a rehab on a house built 1940. The electrical wiring is ungrounded, typical of houses built circa 1940. Of course houses built more recently (circa 1960?) have grounded circuits installed. It seems that rewiring the split-level 2058 sft house will be costly. Can I forego this expense or should new grounded wiring be installed? I’m going to talk to an electrical contractor, but the cynic in me thinks they’ll say, “Of course you must rewire!” What do you typically do in houses you rehab?

Thanks for your advice!


Re: Rehabbing, but rewiring? - Posted by Jim Locker

Posted by Jim Locker on June 26, 2001 at 11:02:08:

Some general comments (btw…I have and MS in Physics, and before I ever was involved in real estate, I did a lot of work with electrical systems, including a lot of high power systems).

First, a GFCI on an ungrounded system will give a false sense of security. The GFCI cannot function if the ground connection is not made; the way a GFCI works is to sense whether a current is flowing on the ground line (which should NEVER happen) and if it is, to trip the circuit.

Second, wiring a three prong outlet into a two wire system is OK. You can connect the ground plug to the neutral wire in the wall. Basically, this means that you wire the ground and neutral together at the outlet. This is OK according to most building codes, and will lead to acceptable performance with modern appliances presuming that you don’t have a wiring malfunction.

Modern three wire systems basically carry the ground and the neutral on separate wires back to the house panel, where they are wired together. This provides an additional layer of safety should there be a malfunction on the neutral line in the house service (which, ultimately, is the dangerous malfunction; a malfunction on the hot wire just takes down the power).

When you wire the neutral and the ground together at the outlet, you lose this redundant safety path - but all your equipment and appliances will work, and you will be protected against any malfunction in an appliance (although you are not protected against a malfunction in the house wiring).

Now, you can use a GFCI on a two wire system IF you connect the neutral and the ground together. The GFCI will then function properly, again with the caveat that you have no protection against malfunctioning house wiring.

Re: Rehabbing, but rewiring? - Posted by Paul

Posted by Paul on June 25, 2001 at 15:18:07:

Hey Tony,

Here in Hawaii electrical work is also grandfathered until you do some electrical work. At that point it is required to update the items your working on. You might want to check and see if it is required that you update to current code since your rehabbing. I imagine every area is different.

Good luck,

Re: Rehabbing, but rewiring? - Posted by Sherry W

Posted by Sherry W on June 25, 2001 at 14:26:36:


I just sold a house built in 1950 with the same. The Home Inspector passed the electrical being ungrounded because it was grandfathered in. The house had to have a upgrade on the electrical panel box though.

I am in Florida, so I don’t know if it is different in other states. Could find out if it is grandfathered in.

Hopes this helps some. But you might get some great advice from the more experienced REI.

Sherry W

Re: Rehabbing, but rewiring? - Posted by Tony (CA)

Posted by Tony (CA) on June 26, 2001 at 21:00:22:


Thanks for your reply. This is all quite interesting. If you connect the neutral and ground together and use a GFCI outlet what kind of “malfunctioning house wiring” are you warning against? That somehow a hot and neutral wire gets crossed? What kind of hazard would that pose? I have one of those 3-prong testers that you plug into and outlet and it checks for crossed wiring. Is there a 3-prong equivalent?


Re: Rehabbing, but rewiring? - Posted by Tony (CA)

Posted by Tony (CA) on June 25, 2001 at 17:10:33:

We had the property inspected when we bought it and the report just said that it looked like some outlet had been replaced over the years with three-prong outlets, giving someone the false sense of security that the outlet was grounded. Said we should either rewire and put in three-prong outlets or replace the newer three-prong outlets with two-prong outlets. He didn’t say we were required to rewire in order to sell. I also checked with the city. They have no requirement for upgrading.

What I wanted to know was whether upgrading to grounded wiring was standard practice or if I could save the money.


Re: Rehabbing, but rewiring? - Posted by Jim Locker

Posted by Jim Locker on June 26, 2001 at 22:22:45:

You would certainly have to be careful to avoid crossing a hot and a neutral if you wire the ground to the neutral at the outlet. This type of miswiring would be quite hazardous.

Assuming you wire it correctly, the possible malfunctions to the house wiring basically consist of one possibility: a connection comes loose through corrosion or other influence (such as a mouse chewing).

If the connection that comes loose is the hot side, then the outlet goes dead. You then track it down and fix it.

If the connection that comes loose is the neutral side, then the outlet may or may not go dead; if any kind of circuit to ground can be found anywhere, then the outlet may still appear to work, but you have a very dangerous condition which could lead to electrocution or a fire.

Typically, in a three wire system, if the neutral goes down then the ground wire is available to carry the current, which greatly reduces the hazard. If a GFCI is connected on the circuit that loses the neutral, the GFCI will detect the current flowing on the ground wire and will trip.

Under the conditions where you wire neutral and ground together at the outlet in order to simulate a 3 wire system, you do not have the protection against the failed neutral wire but you maintain all the other advantages of the three wire system.

Really, failures in wiring inside walls are quite rare. Typically, you will encounter this if you have aluminum wiring in the house (all of that is probably gone by now), or if you have a house in very poor condition.

Wire failures can occur if connections continually get wet (such as due to roof or plumbing leaks that are not attended to), if there is a serious rodent problem in the house (the critters will get bit if they chew on the hot side, but they can chew on the neutral side without harm…until the wire parts), or if the house is deteriorating structurally (walls sagging, floor sagging, things move and pinch or pull wires).

If none of these pathologies applies to your house, then you have no particular issues to watch for when wiring the ground and neutral together at the outlet.

Re: Rehabbing, but rewiring? - Posted by Ron (MD)

Posted by Ron (MD) on June 25, 2001 at 17:35:44:


I don’t automatically re-wire a house if it is not grounded. In fact, I never re-wire a house unless my licensed electrician tells me that the existing wiring is dangerous (which usually means the old wiring is brittle).

I often upgrade fuse boxes to circuit breakers. Actually, I always do this.

Building code here in Baltimore (which is, I think, based on national standards) allows ungrounded outlets. It does prohibit using 3-pronged outlets if there is no ground, for the reason you mentioned. I’m currently selling a house without ground wiring. The home inspector pointed out to the buyer that more modern wiring would be grounded. It made my buyer a little nervous. What I agreed to do was to replace several of the ungrounded, 2-prong outlets with GFCI outlets. These are usually used around water (e.g., kitchen and bath), but the electrician tells me that they act like a grounded outlet. If you have an outlet that you want to use for your TV, computer, stereo, etc., using GFCIs are a good alternative if outlets aren’t grounded.

Ron Guy

Are GFCI Outlets the answer to ungrounded Outlets - Posted by Tony (CA)

Posted by Tony (CA) on June 25, 2001 at 17:54:04:


It surprises me that a GFCI 3-wire outlet could be used INSTEAD of installing grounding wiring. Aren’t GFCI outlets used in conjunction with 3-wire, grounded, wiring?