Electrical Question

[DonTx]

See if someone can answer this for me.

The service panel yesterday had 4 wires coming into the masthead. One was spliced to a smaller wire at the masthead.(wrote up)

No ground rod noted for the home although all but 3 outlets showed to be grounded with the ST.

In the panel, I measured 12 amps on the stranded ground wire (about a 1/0 size). Main breaker was 100 amps.

There was only two wires terminated at the main breaker plus the stranded ground wire coming down from the meter box. I have no idea where the 4th and smaller wire from the masthead went. There was also a fuse box next to the main panel.

The neutral and ground wires were paired up on a single buss (wrote up). Home was built in the late 60's to early 70's.

Questions: 1. How would this system be grounded?

2. Why did I have amperage on the ground wire?

[Jim Katen]

Originally posted by Donald Lawson

See if someone can answer this for me.

The service panel yesterday had 4 wires coming into the masthead. One was spliced to a smaller wire at the masthead.(wrote up)

Is this a house or a commercial building? Was it a three-phase service? Was the wire that was spliced to a smaller wire bare or insulated?

No ground rod noted for the home although all but 3 outlets showed to be grounded with the ST.

Of course you know that the presence of an earth ground has nothing whatsoever to do with proper grounding at the outlets. They ST is just confirming that the grounding wire at the outlet is connected to the panel's neutral terminal bar.

In the panel, I measured 12 amps on the stranded ground wire (about a 1/0 size). Main breaker was 100 amps.

How did you measure the 12 amps? A clamp-on ammeter?

There was only two wires terminated at the main breaker plus the stranded ground wire coming down from the meter box. I have no idea where the 4th and smaller wire from the masthead went. There was also a fuse box next to the main panel.

The neutral and ground wires were paired up on a single buss (wrote up). Home was built in the late 60's to early 70's.

Pictures. I need pictures.

Questions: 1. How would this system be grounded?

2. Why did I have amperage on the ground wire?

Where was the meter? Could it have been grounded there?

Was this a country property?

- Jim Katen, Oregon

[inspectort]

Whats up Don?

I have some possible explanations for this. Some utility providers here require an attachment to the messanger wire, a separate grouding conductor from the service connection to the meter base. It terminates in the meter base on a lug bonded to the meter base. If you have a bond or metal nipple between your meter and panel box, this would provide a false ground, legal at the time of installation. As far as some of your recepticles not showing ground, some older houses are wired with BX cable or metal jacketed cable, the metal jacket is a grounding path to your recepticles, if some of your recepticle were changed or added with the old two wire romex or nmc cable you could lose your ground to those recepticles. For two wire systems the code allows the use of two prong recepticle or if a three prong receptle is desired change it to a GFCI. Just some ideas.

T.

[DonTx]

Sorry, I didn't take no pictures of this box, my bad. It was one of those things I started thinking about after I'd left.

This was a residential home, the meter was above the service panel and I didn't see any grounding rod, however, it could have been encased in the concrete of the sidewalk but I never saw any wire coming out of the brick veneer. Also, there was a gutter box between the meter the service panel/fuse box that fed the service panel and the fuse box.

I got the 12 amps from both a clamp on and my Amp Probe.

This was an older home near downtown Houston.

[inspectort]

SORRY, but it always seems I have an after thought. Did you check for a water ground or even in older houses a gas pipe ground. You may be getting a ground source from one of these.

[rlskfoster]

Don,

If you have an unbalanced load it will read as voltage on the neutral. I am assuming the stranded ground your referring to is a neutral from the service.

You might have three-phase residential service for a motor load,usually, the A/C compressor. I've run across this a number of times in the Fort Worth area.

Buster

[DonTx]

Buster,

You may be correct. The ICP compressor said "Three Stage" on it. I don't think I've ever run across the ICP brand and Preston's doesn't show it.

[Jim Katen]

Originally posted by Donald Lawson

Buster,

You may be correct. The ICP compressor said "Three Stage" on it. I don't think I've ever run across the ICP brand and Preston's doesn't show it.

ICP is International Comfort Products (used to be Inter City). They make Tempstar, Heil & Arcoaire.

Some high-end air conditioning systems around here have two-stage compressors but I've never seen a three-stage one. Sounds peculiar.

In any case, the number of stages in an AC system will have nothing to do with whether it's three-phase or single phase power.

If you suspect that a building has three-phase power, look at the service panel. It'll have three ungrounded buses. Or, follow the service drop to the pole and look for three transformers.

- Jim Katen, Oregon