I use a Draper one that can tell the difference between nails and screws and power cables

Hi MichaelG, the Bosch Truvo TL19792 in cpc.farnel's list might be worth looking at. I've not had or used one, but reading the technical docs, it seems to cover your depth requirement and is a reasonable price that I would pay.

Regards Nick.

I have an oldish Bosch – PDO Multi and it works well, even does a good job of detecting wood 20mm inside a wall…! I have found sensor orientation has some influence on the center of detection – hold the unit vertical battery down gives a sense centre that is approx 15mm lower than if the unit is vertical battery up – the average of the two seems always to work..Left / right position is good, irrespective of unit held up or down.

Live cable sense very good, dead cable sensed in metal detect mode and depends on cable thickness – 2X14 gauge copper wires detect easily at 30mm below plastered wall. 50mm panel-pin head detects @ 25mm.

The PDO is no longer available and Bosch intimates the GMS120 is its successor – I would go for that.

Bosh PDO Multi Manual

Bosch GMS-120

Definitely use an instrument to find buried cables in your walls, about 30 years ago I was refitting our kitchen and believed that I knew where all the buried cables and pipes were, Sods Law I found a cable buried where there was no reason to suspect one, I was drilling with a mains powered drill and suddenly there was an almighty bang and flash of light, I had hit a ring main cable. With luck the drill had penetrated dead centre on the twin and earth cable thereby sending most of the current straight to earth, the blow was powerful enough to destroy the main input fuse, requiring the electricity company to attend for the renewal. My masonary bit that I was using had vaporised, I considered myself extremely lucky to have not suffered any injury, the wife was out when it happened, you can imagine what transpired when she came home!!! Dave W

Michael,

That tool does everything mine does, and a lot more! If I were still mucking around building my house I would ditch mine and get one of those. I think the Drywall reference is for our American friend's peace of mind – I have found on numerous older reviews the American have regularly asked if it works with drywall – since that is the primary construction method there I guess.

Here are some reviews that show it's ability against brick and concrete as well. ( Forgive the patronising video – not my doing..)

**LINK**

**LINK**

The dielectric constant of the materials do play a role in the detection capability, and drywall tends to be air or foam etc in the cavity and the detection signal is less masked compared to when in concrete/brickwork, so the unit is perceived to be more sensitive – meaning that a 'conventional' detector would probably battle to localise the detection area due to the heightened sensitivity. The self calibration of the unit held against the drywall would correct for that I guess.. A the risk of placing myself in the line of fire, I would recommend that unit – if you can live with the size in your application.

Buying a replacement 9V brick (or block) battery for this kind of device seems to be something of a minefield, particularly if you are considering a rechargeable one.

My Bosch DMF 10 detector is quite fussy about voltage but I understand that some devices will tolerate much less than the nominal 9V.

I think the wiring regulations require the wiring to be vertical or horizontal from any wall mounted sockets and switches, a band below the ceiling is also specified for wiring. Of course the shortest route cowboys may have been at work so it is best to check as far as possible.

Mike

I believe it will be difficult to buy a device that will reliably detect live or otherwise cables in a stud wall where they will be 60mm deep if in 2"x4" stud, even is a 3" stud the depth will be over what can be detected by any low cost meter.
Lots of partition walls these days are formed from pressed steel U and Z section so are more easily detected than a wood structure, any cables though may be difficlt to locate.

As said by others the cables are likely to be almost vertical above/below electrical equipment but may also be horizontal in such areas where there are multiple outlets at the same height and on the same circuit.

Also I think it may have been said another cable zone to avoid is at ceiling level and 400mm below.

Emgee