Discuss MCCB Boards in the Commercial Electrical Advice area at ElectriciansForums.net

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Frosty69

Hi people,

Could one of you lovely people tell me the maximum cable size that you can fit in a three phase new style wylex circuit breaker. I have a board to change that contains a couple of 16mm 25mm cables but also one 50mm and the main incomer is 50mm also! What are people using with regards to mccb boards? I have stated Wylex as that what the last electrician has been installing on the site.

Thanks in advance
 

darkwood

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Your lacking info you've give a brand name but not the size and model of mcb/mccb, and if you have this first port of call would be wylex site to download their specs for said mcb's.
If the site has wylex then unless you have issues aquiring the board you want because of space or design restrictions then its usually good call to carry on with the same as the rest of the install.

I believe most mcb do allow up to 25mm/35mm brand dependant and size dependant e.g. Merlin c60 range will fit 25mm (1a - 25a) and 35mm (32a - 63a)

I use Square D or Merlin for MCCB boards .... same manufacturer Schneider and believe they are the same dimensions and in some case interchangeble.
 
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Guest123

Can you clarify wether its MCB's or MCCB's you are referring to as per your thread title?
 
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Engineer54

First of all, are we talking about MCCB Boards or MCB boards??
 

darkwood

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I took it as mcb board with mccb main switch but re-reading it i could be wrong on that, it was the circuit breaker ref' that threw me... i always state moulded case when talking about MCCB's and circuit breakers when refering to mcb's so prob me that made a mistake on that.
 
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Frosty69

Sorry guys written in a bit of a rush. I basically need to change a D/B and for most of the circuits I can use triple pole circuit breakers but I have one circuit that the cable is 50mm so will need to use an MCCB but I wasn't sure if they did a circuit breaker that allows larger cable sizes to be terminated. I just want to try and avoid having to use an MCCB board for the sake of one circuit as the prices seem to be a lot more expensive than normal three phase circuit breaker boards.
Also the incoming supply to the board is 50mm so would need a larger main switch.
Sorry for the confusion
 
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Engineer54

Sorry Frosty, but need more information..

Are the existing breakers MCCB's or MCB's?? If MCCB's then it would be unwise to change to MCB's, especially if any are of the adjustable type. You could be talking completely different time/current protection curves. What sort of breaker ratings are we talking about here??

What sort of loads are the existing breakers supplying, are they sub-mains supplying final circuit DB's??

Most MCCB's will accommodate 50mm cables, and if they don't, you can buy various connection lugs/crimps that can be accommodated. If your talking about the main incoming MCCB, then it will be almost certain that it can accommodate 50mm cables....
 
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Frosty69

Hi Engineer,

The current board is a three way 3036 board. The circuits are supplying other smaller distribution boards with lowish loading no more than 100a. The supply cables to the other boards could be smaller but the cost of replacing the cables would be too much.
 
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Frosty69

I need a 4 way MCCB board but I am struggling to find them on wholesalers websites or online.
 

darkwood

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Now i get you, i know merlin do a Aluminium cable terminal (part 27060) that fits standard c60 mcb's increasing it terminal capacity to 50mm and their standard main switches are 50mm terminals for 100amp or 125amp but if i remember they are not for use in their isobar 4 boards, i would give their tech a ring and explain or any other brand, if i remember others do them too.
 
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Frosty69

Thanks guys just seen the merlin gerin one on rs website its called a power board but I'm not sure its the correct one, will give them a call and cheers david I think theres a hager stockist up the road
 
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Engineer54

Hi Engineer,

The current board is a three way 3036 board. The circuits are supplying other smaller distribution boards with lowish loading no more than 100a. The supply cables to the other boards could be smaller but the cost of replacing the cables would be too much.
All becomes clear now!! ...lol!!!

The Hager boards and breakers look like a good bet and will probably be a cheaper option than the MG equivalent...
 
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Frosty69

Thanks engineer 54, I have just bumped into the Hager salesman at the wholesalers and his spec sheet says the normal triple pole and neutral main incomer will take a 50mm cable. I will have to use one of there uprated 3 phase mcbs that go up to 250 amp! Just waiting for prices now
 
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