Memera 2000 AD MCB

[qubit]

Hello I was looking for a 6A MCB for a Memera 2000 AD CU but only found a type C (same brand) whereas all the other existing MCBs are type B.

It's only a small domestic lighting circuit so I reckon type B is definitely best

Is it okay to fit a type C (since I can't get a B of the same brand) on a CU with all B types fitted?

Or a much better option is it okay to fit a different brand to the above (couldn't get hold of manual for the CU)

The Memera 2000 AD CU is used a lot from what I know can anyone recommend brands which they have had no problem with?

 

[Spark123]

You shouldn't use a type C nor any other without first knowing the earth fault loop impedance is of the circuit.
Type B are not that hard to find, the fuse company do them but like I said - make sure it is suitable before installing it.

 

[hairyben]

Nothing technically wrong with a type C so long as your earth loops support it, which in my experience is rarely an issue.

I wouldn't recommend type C's if there's dimmers on the circuit though, the surge current when a bulb goes can fry them.

 

[plugwash]

You shouldn't use a type C nor any other without first knowing the earth fault loop impedance is of the circuit.

That is true in the stictest sense but it is very unlikely for a C6 to be out of spec on a domestic lighting circuit unless the main earth is faulty (at which point you have much bigger problems than the protection of your lighting circuits)

 

[Lectrician]

MEM MCB's are usually available from the wholesalers in all flavours.

I can do ya one for a fiver delivered.

 

[GaryMo]

I wouldn't recommend type C's if there's dimmers on the circuit though, the surge current when a bulb goes can fry them.

You've confused me with that one!

 

[hairyben]

I wouldn't recommend type C's if there's dimmers on the circuit though, the surge current when a bulb goes can fry them.

You've confused me with that one!

Type C breakers allow a greater short duration surge than type B's, for motor startup and when you're switching banks of fluorescent lighting, type B's can trip, evan when the actual running load is well under the breakers rating.

When a bulb goes the element collapses in on itself and creates a short circuit surge, which is why the MCB can trip or fuse blow. the difference between the fast-acting type B and slow acting type C (and B10's and 3036 rewirables) can often be enough to fry the sensitive low-current circuitry in a dimmer switch thats in circuit with the offending bulb, in my experience.

bulbs used to have internal "ballotini fuses", so the bulb would fuse itself without affecting the circuit, but I don't think they make them anymore cos it's all cheap, cheap cheap nowadays

 

[GaryMo]

I see where you're coming from now.

 

[JohnD]

but only found a type C

I find that incredible.

the Memera 2000 MCB also fits, so does the Memshield 2 MCB

they are all exactly the same size, though the Memshield 2 has greater breaking capacity and bigger terminals.

The AD one probably does not have the green/red open/closed contacts indicator, but the others do.

 

[Spark123]

Type C breakers allow a greater short duration surge than type B's, for motor startup and when you're switching banks of fluorescent lighting, type B's can trip, evan when the actual running load is well under the breakers rating.

I thought they would both go at the same sort of speed when talking about fault currents as they are a mechanical device?
Semiconductor protection is usually an art using fast acting or HBC semiconductor fuses.

 

[hairyben]

Type C breakers allow a greater short duration surge than type B's, for motor startup and when you're switching banks of fluorescent lighting, type B's can trip, evan when the actual running load is well under the breakers rating.

I thought they would both go at the same sort of speed when talking about fault currents as they are a mechanical device?
Semiconductor protection is usually an art using fast acting or HBC semiconductor fuses.

The overload characteristics will be the same, the C type will allow more fault current before tripping.

I've just installed a D32 for a heat pump (ground source hot water), I had to have a look at the regs just to be sure it would go instead of the 100A in the cut-out.

 

[Spark123]

Yep - you're talking energy let through I²t of the breaker being less than the pre-arc energy value of the upstream protective device for the given fault current.
Bit of a pain for circuit breakers as when the current is getting higher the disconnection time doesn't decrease as it is a mechanical device.
Fuses generally do the opposite, the more current the quicker they pop.

 

[Click-Sure]

I've had this with MEM 2000 MCB's before. Turns out they are now sold branded as EATON (MEM's parent company) and this throws some wholesalers.

Its well documented that I'm not a fan of MEM gear anyway.

 

[qubit]

Dang I was supposed to get email notification for this topic

Yes hairy and plug (haha hairy and plug good combination ) I agree with you totally earth fault loop impedance shouldn't be a prob in this situ which is why I overlooked it

I was gonna order from allaboutelectrics cus I was ordering a loada stuff from them but that's done so am left with Screfix now (ordering a loada stuff from them now) and they don't have MEM/Eaton but they've got Wylex (I know some people hate them oh well) and I think I'll get those (NSB06, B6 SP) because on the CU someone has previously used those in 2 slots already and those circuits have worked fine for a long time thanks for all the input I love the physics talk keep it up (I mean the physics talk )

 

[Lectrician]

MEM / Eaton / Long Gone BILL - Excellent gear!

Can't fault it. AM and AS industrial board great. B boards great. AD domestic stuff great. All industrial MCB's will work in all boards. Domestic MCB's will only work in domestic boards.

Little more to know - excellent kit - get using