consumer unit mcb values

[JohnD]

I don't recognise the Proteus, but it is important to know that unlike MCBs (which you can switch on and off under load), with fuses, you must turn the main switch off before inserting or removing them. Otherwise there may be quite a big flash and spark.

It might be worth making a label to fix to the CU saying so. If they do hold cartridge fuses, get at least two of each rating and leave in a clear jar or plastic bag where they are visible and easily accessible. The reason for "at least two" is that sooner or later you are sure to change a fuse but the fault will still be present.

 

[mrcrow]

They look like cartridge fuse holders to me (on the Proteus unit), a format widely used in the Eighties.

Well, obviously you now know that the shower had its own unit added with RCD & MCB. If the conservatory was added on sometime later, then that middle board for the addition makes sense. So the two 30A fuses on the main house board are then most likely either two rings, or ring and cooker.

Best with the main switch off to change them, you push the lever down gently, and will see the fuse in there, they are like plugtop fuses but different sizes per amperage, proberly not easy to get, proteus are made by CEF, but other s may fit, once hinged down the fuse pulls up and out, again refit only with main switch off, to prevent arcing/damage.
To be honest they rarely blow unless an extreme fault, once blown they need replacing with a new fuse, once removed they can be tested by a basic continuity test with a multimeter

Replacement takes just a few seconds - Pull the carrier open, lift the old fuse out, drop a new one in, close the carrier.

The fuses are BS1361 types, like these:

View attachment 89650
https://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/Wylex_Standard_Carriers/index.html

many thanks chaps...i have seen these somewhere with tags on the end to screw them to terminals
maybe in the shipyards

well that clears things a bit and lets me know what to do if they do go...
i will get some just in case...
so now i can do my little test to see what the two 30's are driving and whether one is dead since there is no electric hob or cooker..
i expect the 15 and 5 will be some form of lighting??

again big thanks for a very helpful forum
cheers
geof

 

[stillp]

The 15 would more likely be for an immersion heater.

 

[JohnD]

Yes indeed. Domestic lighting switches, junction boxes and roses are usually rated up to 10A (sometimes 6A for SES or SBC lampholders) so it would be abnormal and wrong to fit a 15A or 16A fuse or breaker.

Domestic lighting circuits are almost invariably 6A or 5A.
10A would be 24 of the old 100W incandescent lamps (or about 120 energy saving lamps), so excessive for an ordinary house. Commercial and industrial lighting circuits may be different.

 

[333rocky333]

I take it you dont have the fusebox cover flap, the circuit designation was often written inside, during that era

 

[ban-all-sheds]

The late 1980's just seemed a little late to be skimping to that extent

House builders show no signs of abandoning their traditional practice of skimping and penny-pinching on every single thing.

 

[mrcrow]

The 15 would more likely be for an immersion heater.

thats gone as well...its a baxi combi boiler now...
thanks

I take it you dont have the fusebox cover flap, the circuit designation was often written inside, during that era

yes that would have been a help...
i reckon as i am soon taking out the kitchen fitments and there are some sockets in the cupboards for fridge and cooker extractor i will shut off the main unit and remove fuse by fuse to see what ones give power to the ring main, lights and whether the cupboard sockets are on the 15 fuse...there are only two..or on the ring
the last house was a 10 year old build and the unit had dedicated mcb's for lots of the requirements
so much easier to work with
cheers
and thanks again
will update as and when i can..

 

[mrcrow]

The late 1980's just seemed a little late to be skimping to that extent

House builders show no signs of abandoning their traditional practice of skimping and penny-pinching on every single thing.

this is what i noticed on the fairly new build i left the poor quality of the kitchen units...almost like photographs of wood on mdf
the best housing though i have had for fairly good finish and 2 year free fix was Bovis built in 2000
cheers
and thanks
geof

 

[kai]

They are sold at B&Q stores - There is a major design fault with the 5amp fuse in this type of consumer unit, it is very easy to accidentally insert a plug top type of five amp fuse into the holder, as they are far more readily available, and cost far less, but only differ in size by fractions of a millimetre - replace the 5 amp ones with a plug in mini-trip also from B&Q when you are there. When the bulb blows, it may blow the 5amp fuse, using the mini-trip will be more convenient and safer too.

 

[333rocky333]

replace the 5 amp ones with a plug in mini-trip also from B&Q when you are there.

How would you fit a plug in minitrip in place of a Din Rail Mounted fuse carrier

 

[mrcrow]

replace the 5 amp ones with a plug in mini-trip also from B&Q when you are there.

How would you fit a plug in minitrip in place of a Din Rail Mounted fuse carrier

interesting point...i think
in fact i was thinking if i could get all the fused items replaced by mcb's then i could isolate easily and not have to have a selection of fuses handy

or would it mean a new consumer unit?

 

[AndyPRK]

Just leave the lighting one alone !

A bulb shouldn't take out the fuse.

 

[JohnD]

MCBs react more quickly, so are more likely to trip than a fuse is to blow, when an incandescent lamp burns out.

As incandescent lamps are being consigned to history, this problem should disappear.

 

[333rocky333]

replace the 5 amp ones with a plug in mini-trip also from B&Q when you are there.

How would you fit a plug in minitrip in place of a Din Rail Mounted fuse carrier

interesting point...i think
in fact i was thinking if i could get all the fused items replaced by mcb's then i could isolate easily and not have to have a selection of fuses handy

or would it mean a new consumer unit?

Aploligies mrcrow, what i was getting at was that the B+Q plug in units DO NOT fit in the board you have.

Proteus may still do mcbs that fit, but could involve changing the busbar, but to be honest, as JohnD says them fuses rarely fail in normal use anyway.
If you want mcb's then maybe the neatest way is possibly remove all 3 of your units and fit just 1 larger one

 

[mrcrow]

replace the 5 amp ones with a plug in mini-trip also from B&Q when you are there.

How would you fit a plug in minitrip in place of a Din Rail Mounted fuse carrier

interesting point...i think
in fact i was thinking if i could get all the fused items replaced by mcb's then i could isolate easily and not have to have a selection of fuses handy

or would it mean a new consumer unit?

Aploligies mrcrow, what i was getting at was that the B+Q plug in units DO NOT fit in the board you have.

Proteus may still do mcbs that fit, but could involve changing the busbar, but to be honest, as JohnD says them fuses rarely fail in normal use anyway.
If you want mcb's then maybe the neatest way is possibly remove all 3 of your units and fit just 1 larger one

that could be my future upgrade after new windows and kitchen
many thanks again
cheers
geof