Using Centaur/proteus Mcb's On A Wylex Board

[Viks]

Hello,

I want to change my 40A MCB to a 50A MCB as i'd like a more powerful shower

I have a old Wylex board and i'm struggling to find any 40A+ MCB's that will fit.

Looking on eBay I've been told that Centaur or Proteus 45A MCB's should be fine for a 10.5kW shower.

I'd just like to confirm with the experts that this is correct

Thanks in advance for all your help

If there's any other information you need, just let me know

Viks

 

[Sidewinder]

According to the manufacturers, no, one must not mix boards and breakers, there are reasons, and they are quite complex, and normally cause a heated debate amongst installers!

 

[ProDave]

What type of board? the old NB type?  the Proteus ones from CEF certainly fit. (just about the only time I set foot in CEF)

If it's that old, I'll bet you don't have the MI to say whether it's okay or not, they didn't think o fthings like that back then.

 

[SLIPSHOD & SLAPDASH]

What did SBS Dave have to say about this ?

 

[Blue Duck]

FWIW 40a+ breakers for old electrium boards are like rocking horse poo and the second hand prices reflect that!

what can we do? :C

 

[kerching]

I want to change my 40A MCB to a 50A MCB as i'd like a more powerful shower

is the cable big enough for a 50A MCB?.....and changing the MCB will not improve the shower anyway [only just spotted that bit]

just wondering

 

[Murdoch]

^^ wot he said

 

[Blue Duck]

should also mention: is there RCD's in place? do they work?

 

[Essex1]

Hello,

I want to change my 40A MCB to a 50A MCB as i'd like a more powerful shower

I have a old Wylex board and i'm struggling to find any 40A+ MCB's that will fit.

Looking on eBay I've been told that Centaur or Proteus 45A MCB's should be fine for a 10.5kW shower.

I'd just like to confirm with the experts that this is correct

Thanks in advance for all your help

If there's any other information you need, just let me know

Viks

The MCB is chosen to protect the cable not the appliance. Take the shower you want. Work out what load it will demand. Check BS7671 to see what cable you need dependant on your chosen installation method. Then choose an OCPD equal to or lower than the maximum that cable can take.

Simples.

 

[Viks]

I want to change my 40A MCB to a 50A MCB as i'd like a more powerful shower

is the cable big enough for a 50A MCB?.....and changing the MCB will not improve the shower anyway [only just spotted that bit]

just wondering

I've not checked the cable yet (mainly because i'll have to unscrew the plastic on my board to see it and i'm not 100% comfortable doing that) but going to a 50A MCB should hopefully allow me to get a 10.5kW shower rather than a 9.5

Having checked my board last night, of the 8 MCB's in there, 6 are Centaur's and only 2 are Wylex, so i'm hopefully pretty safe in getting a Centaur.

After 40A, is the next increment 45A or 50A for Centaur's? I can't seem to find anywhere that can tell me

 

[Murdoch]

I've not checked the cable yet (mainly because i'll have to unscrew the plastic on my board to see it and i'm not 100% comfortable doing that) but going to a 50A MCB should hopefully allow me to get a 10.5kW shower rather than a 9.5

Having checked my board last night, of the 8 MCB's in there, 6 are Centaur's and only 2 are Wylex, so i'm hopefully pretty safe in getting a Centaur.

After 40A, is the next increment 45A or 50A for Centaur's? I can't seem to find anywhere that can tell me

Have you not read the answers to this post?

 

[Andy™]

I but going to a 50A MCB should hopefully allow me to get a 10.5kW shower rather than a 9.5

might even get you a nice fire too if the cable cant take it...

as others have already said (which you seem to have ignored) there is a lot more to this than just changing the breaker. its there to protect the cable, change it and it may not protect the cable against the overload it might now have then you end up with a melted cable or a fire...

 

[Blue Duck]

RCD's ? Bonding? Anyone.......?

If you are not confident to remove the cover on the board how are you going to change the breaker?

Don't mean to sound like a **** but there are some very important questions that haven't been answered.

 

[Doc Hudson]

I've not checked the cable yet (mainly because i'll have to unscrew the plastic on my board to see it and i'm not 100% comfortable doing that) but going to a 50A MCB should hopefully allow me to get a 10.5kW shower rather than a 9.5

Having checked my board last night, of the 8 MCB's in there, 6 are Centaur's and only 2 are Wylex, so i'm hopefully pretty safe in getting a Centaur.

After 40A, is the next increment 45A or 50A for Centaur's? I can't seem to find anywhere that can tell me

Your design logic is flawed, incorrect and possibly dangerous. The size of the fuse is ONLY there to protect the cable it is connected to. Every piece of electrical cable has a maximum amount of current (amps) that it can carry before it will start to overheat, melt, and worst case catch fire. The length of the cable and if it is buried under insulation, in trunking or conduit or open on an wall, all have implications upon the actual max safe working current. You must NEVER increase the size of a protective device, (wired fuse or switch type MCB) without verifying that the cable size and its routing over its whole length is safe to carry the maximum current that the fuse will allow to flow. Just increasing a fuse size without the correct tests and prior investigations of the existing circuit, to verify it is safe, is the classic recipe for the typical house fire that many fire brigades would class as due to an electrical fault. Once you have verified what the circuit itself can carry, then you can decide what size shower to install. You are doing the process back to front. If the wiring is quite old I would think you will almost certainly need a larger cable fitted from the fuse box to the shower plus a 30ma RCD to protect the circuit. From you own description you are not confident working inside a consumer unit so I would suggest to ring a couple of local electricians to give you a cost for checking and or upgrading your shower supply.

The simplified explanation of the science behind your problem is; Electricity always generates heat as is passes along a cable. Bigger current = bigger heat. 50A MCB = more current AND more heat down the cable. 40A MCB = less current and heat down the cable. Common shower cable sizes are 6.0mm2 CSA and 10.0mm2 CSA.  10mm2 cables can carry more current and heat than 6.0mm2.  50A MCB exceeds the maximum load rating for 6.0mm2 cable. You must verify your cable before changing anything.

Doc H.

 

[Murdoch]

RCD's ? Bonding? Anyone.......?

If you are not confident to remove the cover on the board how are you going to change the breaker?

Don't mean to sound like a **** but there are some very important questions that haven't been answered.

Interestingly when the notification comes through your XXXX word is showing in its glory!

 

[Viks]

I appreciate all the replies

The reason i think the 50a will work, is purely because I was told by our Head Electrician where i work, that increasing the MCB should work.

After seeing the replies on here, i'll stick with a 9.5w  

Thanks for all your help

Viks

 

[Blue Duck]

Just pushing the boundaries of the forum software :innocent

 

[Doc Hudson]

I appreciate all the replies

The reason i think the 50a will work, is purely because I was told by our Head Electrician where i work, that increasing the MCB should work.

After seeing the replies on here, i'll stick with a 9.5w

Thanks for all your help

Viks

The statement that 50A would work is correct, but only half correct. If you asked the electrician where you work to actually do the alteration, I think you will find they would only do so if the cable is proved adequate first. Assuming they are giving you a signed electrical certificate with their test readings on. 

Doc H.

 

[ProDave]

I appreciate all the replies

The reason i think the 50a will work, is purely because I was told by our Head Electrician where i work, that increasing the MCB should work.

After seeing the replies on here, i'll stick with a 9.5w

Thanks for all your help

Viks

We are not saying it won't work, we are saying it might work if the cable is large enough to carry the higher current and is installed in a suitable manner.

without that information we are erring on the side of caution and saying don't do it.

Has your "head electrician" had a look at your installation and checked the type and size of cable?

 

[SBS Dave]

Since I have been invited to join the debate, I will do.

ProDave has hit the nail right on the head, with his question,

Has your "head electrician" had a look at your installation and checked the type and size of cable?

That would have been the easiest, fastest, safest, most logical way to answer your question.

Why not ask him?

SBS Dave