Old MEM Fuse Box

[Spike1947]

Hi

I have a old MEM 3 phase Fuse box that has 20A double ceramic fuses per phase ,the question is if I link the 2 x 20A fuses together would I be able to get a 35A feed from it ! , sorry if the answer sounds obvious .

What is the equation for that ! .

Spike

 

[Octopus]

In one word no.

Why do you need a 35a bracker?

 

[Pete999]

Why do you want to use such an ancient bit of kit?

 

[dmxtothemax]

Maybe !
But it is not considered good practice !
Tell what your considering ?

 

[Spike1947]

Thanks for your replies , this 3 phase fuse box is fed from a 16mm2 swa cable and the same size feeds out via one of each of the 20A fuses to a 32A fused breaker about 10 Meter away.

I am wanting to feed from the 32A breaker into a 63A RCB with 1x 32A mcb and a 16A mcb and a 6A mcb to feed some double sockets and a Welding machine ! , each of other 20A fuses in the fuse box are not used ! .

Not sure why a 32A fused breaker is fed from a 20A fuse box !.

PS: none of this is comes into part "P" .

cheers

spike

 

[Spike1947]

Why do you want to use such an ancient bit of kit?

Because I don't have the funds to replace it ,have tried to find a way of upgrading it using the same box but not found anything suitable ! .

 

[westward10]

Are you talking of putting two 20A elements across one carrier.

 

[Bobster]

In a word no.

Two fuses supplying one circuit is a no no.

Doubling up a fuse in a carrier is a no no unless it's designed for that, the only place I've seen it done is with semi conductor fuses feeding a VSD. An they are purpose made 'doubled up' fuses.

 

[Lucien Nunes]

In another word - negative. You should not put heavier wire or two wires in one carrier as the contacts of the carrier are only rated for the current stated and may overheat badly with the extra load. Nor may you connect two carriers together each with wire to their maximum rating, as two thermally separate fuse elements do not behave like one element of double the rating, and there is a massive latent hazard of the circuit not being correctly isolated.

I have seen this done once, I got a belt from it and it eventually burnt out. Please don't repeat this yourself.

 

[Spike1947]

In another word - negative. You should not put heavier wire or two wires in one carrier as the contacts of the carrier are only rated for the current stated and may overheat badly with the extra load. Nor may you connect two carriers together each with wire to their maximum rating, as two thermally separate fuse elements do not behave like one element of double the rating, and there is a massive latent hazard of the circuit not being correctly isolated.

I have seen this done once, I got a belt from it and it eventually burnt out. Please don't repeat this yourself.

OK Guys to put this to bed going to replace the DB .

Cheers Spike

 

[Worcester]

You'll probably need a Type C MCB for the welder circuit, and then bear in mind the reduced Zs for Type C's

 

[Spike1947]

You'll probably need a Type C MCB for the welder circuit, and then bear in mind the reduced Zs for Type C's

Yes cheers for that .

 

[dmxtothemax]

How much load is on the 32amcb ?
You may be able to put it on one 20a fuse
And the other 2 x mcbs on the other ?
It all depends on how heavily they are loaded ?

 

[Spike1947]

How much load is on the 32amcb ?
You may be able to put it on one 20a fuse
And the other 2 x mcbs on the other ?
It all depends on how heavily they are loaded ?

Hi
Thanks for your reply , could do that but I need them to be fed from a RCD ,would have to use 2x RCB's that way , I am trying to think of a way to upgrade the original box with a heavier 3 phase fuse carrier ! , that is not going to be quite expensive .