Check for overloaded cables?

[tgd241]

That sets alarm bells ringing!


Yes, but you need to investigate what has been added to that ring, how, and why all the JB's....

There was a method, more common in bungalows, where a ring would be installed in the loft, then a JB added where a socket was required, with a single 2.5mm dropped to each socket. Is this a bungalow?

I dont think the method you decribe has been used originally. This looks more like supplies to extensions and various addons were needed but they didnt want to put in new circuits or redo existing chases.

I was hoping not to have to do a full tracing out but maybe there isn't as much left to do as I thought. The issue is having to lie down with my face full of stinking, decaying insulation wool around the eaves. Are there any shortcut methods using a multimeter that don't require disassembling the terminal blocks on every socket?

 

[Harry Bloomfield]

Are there any shortcut methods using a multimeter that don't require disassembling the terminal blocks on every socket?

No, none.

 

[JohnW2]

Is there a tool that can easily detect overloaded or overheating cables? I want to add 2 or 3 extra sockets in a property, but the existing installation is a nightmare. I just want something I can plug into each socket to give me a reading for peace of mind (or not). Is there, for example, a tool that draws the rated current and checks for an acceptable voltage drop over time? For example by drawing the maximum rated current and checking for an acceptable voltage drop over a certain time?

It is not clear (at least, not to me!) what your concern is.

Provided only that the circuit was installed correctly, there should be no risk of the cable becoming overloaded or 'overheating'. Specifically, if the size of the cable (and how it is installed - e.g. whether 'buried in thermal installation') is appropriate for the rating of the MCB protecting it, there is no risk of the cable being o'overloaded' to a dangerous extent, and that would remain true no matter how many additional sockets you added (provided they were added correctly').

Virtually any sockets circuits will have far more 13A outlets for it to be theoretically possible to 'plug in' loads which, between them, represent far too great a load (current) for the cable - but if that situation arose, the MCB would trip before any harm came to the cable. Hence, as above, adding more sockets would not change anything.

Asfar as the cable (and risk of it being overloaded) is concerned, total voltage drop is not really relevant - it's the 'voltage drop per metre of cable' (which is directly related to current) that matters, regardless of the length of cable and hence the magnitude of the voltage drop. If a cable of a certain size 1 metre long is safe when carrying a certain current, then the same cable would also be safe (for the same current) if it were 100 metres long.

If you had reason to doubt that the circuit was originally designed/installed correctly (particularly in relation to cable size), then there could be issues (particularly those relating to 'fault protection') other than 'overloading' to consider - but you would then really need an electrician with the appropriate knowledge and test kit to investigate.

Kind Regards, John

 

[martygturner]

I was just going to point out that a ring circuit is already protected from overload by its maximum demand being derated from the maximum performance of the cable which for twin and earth 2.5mm is 25 amps single and 45 amps ring. So the 32 Mcb will trip long before the cable melts. Voltage drop in 150m of twin and earth is 0.49% pretty negligible.

What can cause ia voltage drop is loose connections in the sockets. If you are going to add sockets it may be a worthwhile to ensure that all your existing sockets are sound, the wires are tight and just don't drop out, remember on a Eicr 10% sample of sockets is about it. Tools needed a screwdriver and isolating the circuit safely.

If you are going to DIY, a plug in socket tester in a must - £10ish, which will tell you if all the sockets are wired round the right way have a earth and are definitely off before you start grabbing wires.

 

[JohnW2]

I was just going to point out that a ring circuit is already protected from overload by its maximum demand being derated from the maximum performance of the cable which for twin and earth 2.5mm is 25 amps single and 45 amps ring.

I'm not sure what you are trying to say here.

The current-carrying-capacity of Method C 2.5 mm² T+E is 27A.