Electrical problem

[jeraldo]

I have an outside elecricity supply to my shed coming from a separate switch in the consumer unit which goes outside, underground and to a mini circuit breaker in the shed before feeding the sockets and lights. We recently had work done in the garage and slightly altered the cables indoors and now nothing works in the shed. However, there IS a supply going there as the sockets, etc, live feeds show a positive on the elecrical screwdriver light. What could have gone wrong? It's not tripping out on the circuit board but nothing works outside any more! Help!

[LCDMAN]

Could be any one of a number of things!

You say "slightly altered the cables indoors " - how and why?

Don't trust an "electrical screwdriver light" either - we electricians don't. It tells you absolutely nothing about the voltage or current present, as it can be triggered by tiny voltages and a minuscule leakage current {which is always present}. Best bet is to throw it in the bin and invest as little as maybe �10 on a proper meter from Maplin.

Without surveying the installation, my best guess is either that the supply from the house to the shed is no longer connected, or incorrectly connected or switched off.

[jeraldo]

Thanks LCDMAN. I have checked and all seems turned on. When I turn off the switch at the consumer unit the screwdriver no longer registers a light ... Any more thoughts? Could it be an earth somewhere ...?

[buildersmate]

"Could it be an earth somewhere ...?"

The function of the 'earth' is a safety one - it helps to protect against electric shock. It is perfectly feasible for an electrical circuit to apparently function correctly without the earth - it is just damn dangerous. As LCDMAN said, please throw away the screwdriver-thingy and buy a proper meter. You (or someone who understands how current flows) need to trace through the circuit, measuring the potential difference between the live and the neutral circuit at various points to find out where the break in the circuit occurs.
It seems possible that you have a break in the neutral return line from the electrical devices back to the consumer unit (the black wire in old red/black cable wiring, the blue wire in new brown/blue wiring)

[beso]

It sounds like a high resistance connection, most likely a break in a wire. Solid core conductors can fracture relatively easily. Enough of a connection to light the tiny load of the screwdriver but not enough to run a significant load.

My guess would be a cable has been disturbed in the distribution board during the internal work.

[Disco Fever]

I'm a sparky and I agree with beso it sounds like a high resistance as when you put a small load on the system the voltage disappears...