Circuit Breakers - What Does Type 2 Mean?

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andrewjameshoward

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I have a (UK domestic, private house) Merlin Gerin consumer unit with Multi9 C45N circuit breakers and I want to replace one of them. When I look for replacements, all the similar ones for sale (ebay mainly since this range appears to be discontinued) seem to be labelled "Type 2" whereas the (really old) existing ones don't say type anything. What does Type 2 mean? I've looked at the wiki and it talks only about a Type ABC classification.

(In case someone wants to say, why do you want to do that? I have a circuit which trips the main switch about once every 3 months. If everything is disconnected from it, it still won't come back up. Leave it for a day or so and then it will. Every socket has been removed, carefully inspected and replaced. So that seems to narrow it down to an intermittent fault in one of the ring main cables and one in the breaker. It seems sensible to try replacing the breaker before embarking on a more exhaustive search to find the fault elsewhere).
 
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Will not trip within 100ms at 4x rated load but will trip within 100ms at 7x rated load.

Type 2 are for household use. Get that one.

Steve
 
They are classifications relating to the fault current needed to trip the breaker.

Older type 1, 2, 3 are equivalent to modern type B, C, D (not ABC).


If your main switch is a Residual Current Circuit Breaker (RCCB) then this indicates a certain type of fault unrelated to the MCB.
 
Cheers. half an hour of googling, I just couldn't find that.

Yes, BCD not ABC. I just meant there were letters not numbers.

I suppose you're right about the MCB too. How could a fault in a single pole MCB trip the RCCB? Unless some current was somehow leaking to earth within the consumer unit. Highly unlikely. I suppose I am clutching at straws. Problem is that it is an intermittent fault and by the time an expert turns up to diagnose it, it has gone away again (been there, done that). The best I can think of to do is next time the fault recurs, disconnect all the sockets (and the ring), then connect one by one until it manifests itself. Sod's Law says the fault will disappear again half-way through this process!
 
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Changing the breaker will do nothing

If it trips with the mcb off, you have a neutral to earth fault, and on it could be live or neutral to earth.

Likely an appliance over the wiring but not 100%
 
These faults are very difficult to find and may be the accumulation of several appliances leaking very little to earth (normal) adding up to enough to trip the RCD.

If it is one appliance then motors and heaters are the most likely.

Another likely cause is moisture in an outside fitting when it rains (or a leaking appliance indoors).
That would explain the delay in being able to switch on again.
 
The C45 on ebay are either fake or secondhand old tat

A C60 replaced them
 
Is a C60 (or C60N) completely compatible? It doesn't seem to use the little fork connectors which the C45 does.
 
pic_280_bg.jpg

Those forks you are talking about just clip into the round hole over the top screw. Although I don't know why we're still discussing them.....that's not where the fault lies
 
You're right. I don't think I'm even going to bother replacing the MCB. I'll just have to bite the bullet with more detailed investigation.

As regards all the ebay stuff being 2nd hand "tat" though (accepting that one would need to be very wary of fakes), all my MCBs are 30+ years old and working fine. So that's 2nd hand enough. A 2nd hand one from ebay is around a fiver. A new C60 from RS-Online is about £50!
 
Anybody who buys a non new-build house and doesn't immediately have the CU replaced is using second-hand MCBs.
 
andrewjameshoward said:
As regards all the ebay stuff being 2nd hand "tat" though (accepting that one would need to be very wary of fakes), all my MCBs are 30+ years old and working fine. So that's 2nd hand enough. A 2nd hand one from ebay is around a fiver. A new C60 from RS-Online is about £50!
Click to expand...

But you likely know the history of yours.
Most 2nd hand merlin comes from commercial and who knows how many times they have been blown up by faults over a possible 30 years or constantly on in a poor envirement and the switching mechanism a bit gunked up.

Regarding the forks you reuse your old one, undoing the screws releases it.

Even the C60 range in now phased out and replaced with the Acti 9 range
But as others say you maybe wasting your time.
 
Putting my own little problem aside, it does open up a wider question.

Anyone could have a Merlin Gerin consumer unit and want to replace the components, or add a circuit in a blank space or otherwise change the configuration.

If they are to shy away from 2nd hand components with uncertain history and end of range leftovers at ginormous prices, what are the compatibility issues between C45, C45N, C60whatever and Acti9?

It's not so difficult to choose the right spec - poles, current, curve type etc but are they all interchangeable? Same physical dimensions, fittings, cable diameter? The last couple of posts touched on this but I didn't really follow.
 
D

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