ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades British Grounding Arrangements

Bill,

The main service fuse is located on the board right next to the meter. This board is mounted inside the house in all older installations, or in a meter cabinet outside for some new homes.

Although accessible to everyone, the fuse carrier is sealed by the power co., as is the meter case and terminal cover (meters here aren't the plug-in type).

The short leads between fuse block & meter are clearly visible to the meter reader, so any tampering here would be spotted fairly easily.

I think the most vulnerable area is the cable before the fuse in homes with an overhead service. The overhead lines terminate on a bracket at roof level, then two double-insulated single cables run from there down to the service block.

In some homes these cables are actually routed through the roof space. Unlike most (All?) American services, none of this stuff is enclosed in conduit or raceway, so it wouldn't be very difficult for someone to tap the cables in his attic. Chances are that such a tap wouldn't be discovered for years.

I've never seen aything from the utilities about illegal taps being a big problem. Maybe they just rely on the fact that the majority of people would be too scared to interfere with hot 240V cables.

Paul,

I once saw something like you were describing. A customer had just moved into a house previously owned by a utility worker. The SE cable outside passed through a small overhang on it's way down to the Meter (outside). I found signs in the attic that the previous guy had tapped into the cables as they passed through the overhand and soldered 40 Amp fuses to the wires and continued down to an Electric Stove. The fuses were hanging in mid-air! Definitely a 'Kodak Moment' I may go back there again just to take a picture sometime. (it wasn't live anymore and customer was going to remove it .. yeah, maybe)

Bill

Ah well... At least the illegal tap had fuses, even if the method of installation left something to be desired!

I remember seeing a TV documentary some years ago about the poor "barrio" districts in parts of India. The houses (shacks) didn't have any official supply, so many people just ran small flexible cords out of their windows and with the aid of a ladder wrapped them around the overhead lines running along the street.

They said the PoCo came along and ripped them all down every couple of months or so, but within a week most would be back, even though many people got electrocuted while performing this task.

The picture that sticks in my mind was the guy balanced up the pole connecting his wires (bare-handed) while working around all the other unofficial "service drops" already there. There must have been about 25 at the one pole.

O.K. folks, here's the final installment of this saga: Modern trends.

The diagrams represent the basic systems as they were installed and all of the systems shown are still in use in various areas of the country.

Since the 1980s however, one or two trends have been emerging clearly.

First, main RCDs (GFIs) have become much more common. In part this is due to the demise of the voltage-operated ELCB (diagram #4) which has not been made for about 25 years. When grounding is by way of a local rod only (#3), the GFI is just about essential because of the high loop impedance.

On all older installations the ELCB (of either type) was always a separate unit, as shown. Many of the latest distribution panels are modular, and can be fitted with either a simple double-pole main switch or a GFI. So in modern panels the GFI may be separate or may be incorporated in place of the main switch.

We're also seeing a main GFI employed more and more often with the urban and PME systems during rewires. Some panels have a split busbar so that one or two circuits (usually lights) are tapped off before the GFI.

The second main trend is toward the overhead systems going to PME. The power companies have been installing the extra ground rods so that customers have the option of grounding to the neutral if required. A lineman for this region (Eastern Energy) told me recently that all overhead supplies in this region are now equipped for PME.

Of course, most of the houses were wired before PME, so they still have their rods and main GFIs (or more likely voltage ELCBs) for grounding, but it means that when rewired grounding to the neutral would now be allowed.

There have been a few other gradual changes as well, such as the introduction of outside meter cabinets on new and refurbished homes. When these are installed in rural overhead service areas, the utilities like to use underground feeder from the cabinet to the nearest pole.

This cable is now usually a central live with concentric neutral, PVC sheathed. When overhead service drops are replaced to an inside meter, this same cable is used in place of the original two singles.

Paul,
I sent the first two drawings to Scott. Please proof read when posted.
Nick

O.K. Nick, will do.

Where are they being posted: A new thread or to replace the existing links in the above messages?

Sorry about the delay guys!

I'll convert them tonight and post them in the "Tech Reference" area, with linked discussion thread in this forum area.

All this is of course - "Pending any conversion problems"

Scott SET