problem with 60 amp fuse

[easilec]

I changed two fuse boards in a house that is converted into 6 flats, these 2 boards control the communal lighting, which work on PIR sensors, so are never left on for long, they also control the fire alarm, emergency lights and the immersion heaters, one on each board.
So in each fuse board we have a 32 amp ring, a 16 amp water heater circuit, a 16 amp radial socket circuit and 2 lighting(6 amp) circuits.
When i turn the power on everything is fine, but then when i leave the job, an hour or so later i have the landlord on the phone saying nothings working, when i go back the 60 amp fuse has blown, but it seems to take an hour or 2 to blow, can anyone shed any light on this for me as i've been back 3 times now and am going out of my mind.
thanx, james.​

 

[telectrix]

measure the total current drawn on the 60A fuse. sounds like it's pulling about 90A. is there a cannabis farm in the attic?

 

[Top Cat]

^^^^^^^^^^^^^^As above^^^^^^^^^^^^^

Check for extension leads coming off sockets in communal areas (the landlord pays the bill for each flats electricity).

Worth staying around for an hour with your clip on Amp meter.

 

[tony mc]

Has this fault just started happening after the CU were replaced!

 

[Top Cat]

Has this fault just started happening after the CU were replaced!

Now there's a thought!!!!!!

 

[sedgy34]

yeh a clamp meter will shed some " light " on your problem pun intended lol

 

[sedgy34]

this 60a fuse that blows is it the main DNO fuse???

 

[aaelectric]

I had this problem before and it turned out that they supply cable from the fuse to the ccu had a snip where someone had cut of sheath and was arking cauding the fuse to blow you need to do an isulation resistance test on the cable or if its before the meter call dno

 

[SPARTYKUS]

Is the 60A fuse still supplying the house, as in, all six flats?

 

[easilec]

Is the 60A fuse still supplying the house, as in, all six flats?

No the fuse is powering the 2 mains board that supply the down and upstairs lights, emergency lights, a fire alarm and an immersion heater on each floor.

 

[easilec]

Now there's a thought!!!!!!

YES it has.

 

[sedgy34]

YES it has.

so didnt anything flag up when you tested your works ie ze,zs r1r2 etc

 

[Top Cat]

No the fuse is powering the 2 mains board that supply the down and upstairs lights, emergency lights, a fire alarm and an immersion heater on each floor.

You said in earlier thread about a 32A ring circ. What does that do?

 

[tony mc]

If that this case back out with the test gear and check double check everything from scrath !

I take it that its only the 60 A fuse blowing nothing else on the consumer side tripping on the new boards!

 

[easilec]

I do apologise there is a 16 amp radial socket circuit.

 

[easilec]

Tony mc this is correct, nothing else trips

 

[sedgy34]

Tony mc this is correct, nothing else trips

whats the earthing arrangement and ze

 

[SPARTYKUS]

EWell there is a clue.....

If its just the main fuse then don't you think there must be a problem betwixt fuse and....board!

 

[SPARTYKUS]

Easilec whereaboooots are you West Mids? I'd be happy to help

 

[tony mc]

So start looking between the boards and the fuse first IMO

 

[sedgy34]

the supply cable needs to be verified here!

 

[Knobhead]

Why???

 

[sedgy34]

Why???

i think you asked why to my comment, supply cable from the 60a fuse to CU,s

 

[GLENNSPARK]

IR test between poles on the DP switches.....check main earthing...see how much currents on it.....

 

[GLENNSPARK]

also....hang around for a bit....see if the current draw suddenly jumps up....as if theres a "secret load" anyware..lol....

 

[Knobhead]

i think you asked why to my comment, supply cable from the 60a fuse to CU,s

You didn't make it very clear.

 

[lamb]

I would check the connections on the cutout/ryefield fuseholders that hold the 60a fuses that keep blowing.
If there is heat build up here due to loose terminations/fuse blades/contacts the heat could melt the fuse wire with only a few amps flowing.
By the time you return to site the fuseholder will have cooled down so you would never know.

 

[Knobhead]

A quick way to check for heat build up is the temperature sensing labels sold by RS. I’ve used them on fuses before. Will have a look for them later, busy cooking at the mo.

 

[GLENNSPARK]

A quick way to check for heat build up is the temperature sensing labels sold by RS. I’ve used them on fuses before. Will have a look for them later, busy cooking at the mo.

your always bloody cooking Tony...lol...

 

[SPARTYKUS]

A quick way to check for heat build up is the temperature sensing labels sold by RS. I’ve used them on fuses before. Will have a look for them later, busy cooking at the mo.

I bet it isn't Puy lentils in creme fraiche and white wine, salmon baked with lemon and garlic, new potatoes, 10 minute old asparagus and roast parsnips coated in butter???