Wire tracing - what to use as earth/ground in apartment?

[victorhooi]

I'm trying to trace some circuit breakers in an apartment (using one of the Amprobe AT-6030 wire tracing kits).

I've connected the red on the transmitter unit to the hot (active) wire on the circuit under test.

For the black, I normally use a separate ground - e.g. alligator clips around a metal plumbing fitting, or if I'm in say, a datacenter environment - there's usually earthing points exposed that I can use.

(The manual for the AT-6030 mentions that you should use a separate ground when tracing, due to signal cancellation - and when I've tried using the earth pin on the same circuit, it doesn't work - I assume there's probably some theory here that I could learn more about).

However, I can't find any earth points in the apartment to use. And it's not on the ground floor - so it's not like I can go outside, and drive a ground stake into the ground.

I did also try the earth bar in the distribution board - but I wasn't able to get any signal there on the receiver unit - I assume due to the aforementioned signal cancellation issues (since that's also where the breaker I'm trying to trace is).

Does anybody have any suggestions on what to use as an earth/ground point for the transmitter, so that I can get a clear signal for tracing?

[johansen]

All the grounds and the neutrals are connected anyways in the main panel, so i dont know why it would make much difference.

[Shock]

It says in the manual how you use it.

... or outlet ground connection of an outlet on a different circuit. It is important to understand that an acceptable separate ground is NOT
the grounding terminal of any receptacle on the same circuit as the wire you wish to trace.

In this context the same circuit are wires run close together, it cancels the signal. A separate circuit would likely be the kitchen instead of the master bedroom or bathroom etc. Rooms in close proximity could be the same circuit, by using an earth on the other side of the apartment the wiring is likely run in a different direction. The reason your taps might not work as a ground/earth may be they aren't all conductive or using metal pipe work.

I'm unsure why you are even using this tool. I would have thought it's trivial to find out which breaker is which outlets. I suggest not messing around unless you know what you are doing. It's illegal to make changes and if you have a problem you should really get an electrician out.

[jonpaul]

 

Depending on your location and the local electrical regs, a safety earth  should be on the electric sockets, metal  frames of appliances, cold water pipes.
professional circuit tracers like Ideal, Fluke use a RF TX that lugs into a socket and a contactless probe.

No earth or grounds are used.
Jon

[f4eru]

All the grounds and the neutrals are connected anyways in the main panel, so i dont know why it would make much difference.

Hmm, nope. Neutrals are separated from PE for a very good reason: safety of people against shock (especially in case of loss of connection on a N wire...).
It also depends heavily on the country regulation.
in USA, the earthing scheme is TN-C-S or similar wit a PE<->N at the main breaker, other countries differ.
Just as a really opposite example: In France, for example, with a T-T earth, there is no connection at all between PE and N, and furthermore, all circuits are protected by a few panel-mounted 30mA RCDs, making the neutrals sensitive between different circuits, and furthermore again, neutrals are switched in each and every power breaker, making each neutral belonging to exclusively to a circuit specifically.
The big main breaker also has a 500mA RCD function (protection against fire and contact in panel before 30mA head RCDs.)
There is often a few volts between N and PE (AC and/or DC due to soil electrolytic effects)
No mixing of neutrals possible at all.
Any connection N-PE or between two different N would result in RCDs tripping.
A circuit is completely disconnected when the breaker is down, including N.
Very safe and clean wiring reg.