Dealing with an overloaded circuit

[assegayer]

hi guys another query.

say a customer had a overloaded circuit where it was just down to pure ****e design, how would an electrician deal with this. I could only think of a rewire of that circuit as the only viable option. as off course u cannot just upgrade the protective device.

i ask because i have a mate living in a single room and when he puts the kettle on after a little while 'flick' the breaker is off, now i havnt seen the job but i have a feeling the socket circuit in his room is joined with other rooms thus accumlative overload. (off course these are all assumptions as havnt seen yet)

 

[telectrix]

could also be an under sized or a "tired" MCB.

 

[Darkwood]

Does he have electric heaters plugged on the ring etc ...is the kettle faulty and only shows when the element is hot ...without been hands on here its all guess work.

 

[davesparks]

It depends how significant the overload is, and the accessibility of the wiring.
You can either reduce the load, or split the circuit into two.
If it's a ring you might get away with splitting it in half and making it two 20A radials (unlikely)
Or you could run 2x 2.5 to an accessible point somewhere near the middle of the ring and split it into two rings.

 

[assegayer]

Does he have electric heaters plugged on the ring etc ...is the kettle faulty and only shows when the element is hot ...without been hands on here its all guess work.

I can definitely wipe that fault out of the way as he said when he plugs the kettle on the shared kitchen socket it works fine, but he doesnt always want to go to the kitchen (for privacy off course)

 

[Richard Burns]

As he is living in a single room, if the house is specifically wired, I would suggest that the circuit is designed as a 16A (or maybe even 10A) radial for that room and that other loads in the room are taking the breaker over the overload limit of the breaker.

This is one of the methods used for limiting current draw in multi occupancy houses.

 

[assegayer]

As he is living in a single room, if the house is specifically wired, I would suggest that the circuit is designed as a 16A (or maybe even 10A) radial for that room and that other loads in the room are taking the breaker over the overload limit of the breaker.

This is one of the methods used for limiting current draw in multi occupancy houses.

so how would you go about sort this problem out.

 

[davesparks]

so how would you go about sort this problem out.

Get a lower powered kettle

 

[assegayer]

Get a lower powered kettle

in this situation he probably will, but say just for knowledge if somebody just wanted it to work without getting a lower wattage kettle, all i could thing of is either rewiring the circuit, or spuring of another appropriate circuit (with appropriate fusing off course if required)

 

[assegayer]

lol forgot to say, before another 'so called sparks' came to check the problem out and he had but a small link of cable in the fuse board between the feed and load side of the mcb, so rendering the mcb useless so the kettle worked. however after the landlord was doing some refurbishments and another spark came by and removed the link and said its not safe, but did not attempt to solve the problem.

 

[davesparks]

in this situation he probably will, but say just for knowledge if somebody just wanted it to work without getting a lower wattage kettle, all i could thing of is either rewiring the circuit, or spuring of another appropriate circuit (with appropriate fusing off course if required)

If it is tripping because the circuit has been restricted to a specific size deliberately to prevent the total load of the installation overloading the incoming supply then there is nothing to solve!

 

[assegayer]

If it is tripping because the circuit has been restricted to a specific size deliberately to prevent the total load of the installation overloading the incoming supply then there is nothing to solve!

my poor wording, say it was a poorly designed circuit the supply can off course take it, its an 80 amp supply mate, with a 20amp radial, forget the situation with my mate now. im just giving an example if it was with someone else who wants to be able to put a kettle or any appliance with that load on

 

[davesparks]

See post 4

 

[assegayer]

appreciate your time mate

 

[Richard Burns]

If you are considering the general case of a circuit with a low rating breaker that does not meet the requirements of the load applied, then the resolution would depend on the way the circuit has been installed.

If the cable were 1.5mm² T&E on a 16A breaker if the conditions of installation were perfect then you may be able to take the breaker up to 20A, however this would require careful consideration as the only method allowing 20A CCC is clipped direct (or free air) with no other derating factors.

If the circuit were for some reason installed with 4mm² singes in conduit then you may be able to raise the breaker to 32A in good conditions.
However these are best case scenarios and due consideration of all relevant factors would need to be taken into account.

There is no one simple answer but I would point out that the majority of circuits (with possibly less emphasis in domestic circuits) are designed at the time of installation to just meet the minimum requirements because this is the most cost effective method of installation and cost is often an overriding factor. This being the case there may well be no leeway available to make changes to the capacity of a circuit without rewiring the circuit.

 

[assegayer]

appreciate the advice richard, you always give such a thorough explanation.

I went to see the job today and to my amazement the sockets where on a 6 amp mcb wired in 1mm. This was feeding (attempting to) a kettle, microwave, iron, tv and refrigerator he lives in a single room. obviously it trips out the 6 amp pretty quickly even if he was just to use say the tv and kettle.

luckily his single room is right next to the CU where there is a ring 32 amp and a 20amp radial with just one socket below the cu for a washing machine to plug in every now and then.

he is literally 2 or 3 meters from cu i was going to extend the raidial and add a socket in his room. then take another seperate supply from a 32 amp ring mcb (confirmed it is ring from testing) so there will be 3 line conductors in the mcb 2 for the orignal ring and one for my spur.

i want to do it this way because i know the 20amp will not hold out hes adding another heater soon for the winter and his girlfriend lives with him.

its all going to be surface clipped highlevel no surface trunking to double patress boxes.

your thoughts anyone?

 

[Richard Burns]

A 6A supply is really ridiculous, and the minimum size cable for power is 1.5mm².
Before making these changes it would be relevant to ensure that the landlord is happy with this arrangement! From the description of the circuits I would say, not!
Generally a 20A radial will be sufficient for most purposes and adding a spur from the ring would be redundant and indicative of excessive power use even in a single room. Unless as you say the only heating is electric.

 

[assegayer]

A 6A supply is really ridiculous, and the minimum size cable for power is 1.5mm².
Before making these changes it would be relevant to ensure that the landlord is happy with this arrangement! From the description of the circuits I would say, not!
Generally a 20A radial will be sufficient for most purposes and adding a spur from the ring would be redundant and indicative of excessive power use even in a single room. Unless as you say the only heating is electric.

the landlord genuinely does not give two sh****. The only heating is electric there is no central heating.

EDIT: dont know if you read one of my other posts but he jsut brings cheap 'sparks' that do stupid things like by passing the mcb. however recently they upgraded the board and the 'more real spark' removed the link and said it wasnt safe. Initially my mate wanted me to put the link back in as i got the usual 'its been working with the link for 3 years no problem' statement.

 

[Richard Burns]

OK then take one cable from the ring MCB joint it safely to a new length of cable and extend the ring out into the customers room and supply the sockets you require and finish back at the CU.

 

[assegayer]

OK then take one cable from the ring MCB joint it safely to a new length of cable and extend the ring out into the customers room and supply the sockets you require and finish back at the CU.

Would it be bad practise to just add it on to the mcb and have 3 line conductors 3 neutrals and three earths, because at the end of the day im still using 2.5mm cable protected by a 32amp mcb. (just enquiring)

 

[davesparks]

Would it be bad practise to just add it on to the mcb and have 3 line conductors 3 neutrals and three earths, because at the end of the day im still using 2.5mm cable protected by a 32amp mcb. (just enquiring)

It's fine to take a spur from the mcb like that, but is better to open and extend the ring wherever possible.

Plus extending the ring allows you to add more than one point wheras a spur is limited to one point

 

[assegayer]

It's fine to take a spur from the mcb like that, but is better to open and extend the ring wherever possible.

Thanks for that mate, guess ill extend the ring as both you and Richard suggested.

 

[Richard Burns]

Such an unfused spur from the ring could only supply, at maximum, one double socket, if you extend the ring you can have as many sockets as required.
The 20A radial would be simpler to come from to supply all your required sockets but would limit you to 20A.