Bizarro Ground Issue

[Bryce]

Hi guys,

Moved into an older home last month - which is why I've been MIA for quite a while. The house has old old old electrical - Federal Pacific breaker and aluminum wiring (le sigh) - which includes glorious 2 prong adapters. At some point the wiring in the kitchen, garage, outside and both bathrooms was "upgraded" to include ground (via the tried and trued method of piggybacking off the telephone line's cold water pipe ground!) but I am unsure as to whether or not any of the other outlets were.

I am suspicious, though, because all of the outlets have a ground wire unceremoniously "nailed" into them. Is this how "handymen" fix things? I digress. That's my best guess as to what that wire could be - what else would literally have a nail driven into the receptacle with copper wire wrapped around it?

Anyway, the real reason I'm here is this: I've been measuring the voltages of various outlets in the house. All of the "properly" grounded outlets measure fine, but the ones that are suspect measure the following:

Hot to Neutral - 117V
Hot to Ground - 25V
Neutral to Ground -0V

I am thinking this is either (1) stray voltages or (2) short. My money's on (1), but seeing as how I've never had to deal with an electrical system older than Watergate I am unsure what to make of this. My dad's an old phone man and told me that aged aluminum wiring has a tendency to fray and start arcing. Fire is a primary concern, but I'd also like to avoid shock between my guitar and a microphone. Any thoughts on this? My computer's battery backups usually complain about the lack of a ground but they aren't here; half of my power strips are and half aren't. You can see my confusion.

Thanks fellas!

Bryce

PS. How are things in Hiwatt land?

[OldSchoolDave]

Youse guys gotta stay put for awhile! What's with all the moving? Should I expect to see you on America's Most Wanted ?

I'm going to go out on a limb here and say that, while a Neutral to Ground measurement of 0 is usually a good thing, in the case of those outlets, no Ground is connected. If it were, I would expect 117v Hot to Ground reading, not 25v.

Don't know how big a project you're looking to get into, but that house sounds like it's due for a complete rewire. There are some pretty good surface mounting options these days. Not as pretty, but not nearly as dangerous as aluminum .

Dave

[mikhailwatt]

Anyway, the real reason I'm here is this: I've been measuring the voltages of various outlets in the house. All of the "properly" grounded outlets measure fine, but the ones that are suspect measure the following:

Hot to Neutral - 117V
Hot to Ground - 25V
Neutral to Ground -0V

Depends on how well "grounded" your ground reference is.

Is it really aluminum wire, or "tinned" copper? I had some of that in my first house, built in '41. Aluminum wire itself can be ok, but only if it is properly terminated. Temperature cycling over time will tend to loosen anything terminated under a bolted/screw connection. Then you get hot spots, then possibly arcing and a fire. Not good.

I've never heard of the "nailed into the receptacle" grounding method before. Got any pics?

[Bryce]

Did a bit more digging around. Looks as if it's actually copper wire from receptacles to panel. I had assumed it was aluminum with copper terminus but I was wrong. Tad weird, but I'll take it!

I'm not going to bother undertaking any electrical work until we know if this is a house we might one day buy. Why do all that work when an outdated electrical system is a perfectly good bargaining chip?

I think I will put in a GFCI at the beginning of every circuit, though. How well do those things work with amplifiers? Some folks over at the, ahem, palace seem to think that big ole vintage iron will trip them, but I'm not buying that. As always, thanks for all of your thoughts, guys!

As far as moving goes... man, Chicago was a son of a bitch. Not sure a town's ever so thoroughly whooped my ass! We considered Minneapolis briefly before realizing your winters were worse than Chitown's. Brrr.

Bryce

[OldSchoolDave]

We considered Minneapolis briefly before realizing your winters were worse than Chitown's. Brrr.

Yeah, there is that...

Sorry to hear Chicago didn't work out. At least there, you were on the way to Hiwatt Valley!

Dave

[mhuss]

A properly functioning GFI will only trip if there is a real problem with leakage current. The size or nature of the load (including PTs) should not affect it, but a leaky old "death cap" might.

--mark

[Bryce]

Hey, I might be a corksniffer, but I'm not a Fender Forum-using two prong-sportin' luddite! I keed, I keed. No death caps 'round these parts and only grounded plugs, too.

I can't imagine having toured in the 60s/70s with the kind of wiring clubs/amps had back then. I guess that's what cocaine's for, eh?

Bryce

[mhuss]

I can remember grasping the guitar strings and gingerly touching the microphone to see if the ground switch needed to be flipped.

Worse, if you forgot and your lips performed that test.

--mark

[OldSchoolDave]

I can remember grasping the guitar strings and gingerly touching the microphone to see if the ground switch needed to be flipped.

Eventually, I "smartened up" and simply leaned the guitar forward, so the low E touched the mic. Spot welded a couple of those, but it saved some irreplaceable body parts .

Dave