Domestic BG Consumer unit swapping MCB.

[ericmark]

I worked mainly commercial and in most distribution boards I have worked on the release tag for the MCB is under the output terminal so to swap a MCB was a simple operation you switched off removed cable slacked off terminal to bus bar released tag and lifted clear very simple.

However I came to swap one for my daughter she had this BG 10-Way High Integrity Populated Insulated Consumer Unit Dual 63A RCD fitted and the release tags were under the bus bars so to remove one MCB the whole bus bar needed to be removed.

On refitting the bus bar one had to be very careful to ensure the terminals were open it was very easy to get the bus bar below the clamp rather than in the clamp. Laid on it back with original fitting not a problem but once fitted it really needed a special tool to press on all 6 terminal screws to ensure the clamps were open I had to really struggle with a mirror to ensure the bus bar was inserted correctly.

I am now not surprised there are consumer unit fires it would be so easy for an MCB to be only touching the bus bar rather than clamping onto it and clearly any torque screwdriver would do nothing to redress this problem.

I am sure other consumer units I have used the bus bars were fixed and the MCB was actually clamped in not by the din rail clip but by the bus bar and if you got terminal clamp wrong side of bus bar the MCB would be lose so easy to detect. Is this just a cheap and nasty consumer unit?

 

[PrenticeBoyofDerry]

There are a number of CUs that have exactly the same issues as what you have described with BG board. I have similar problems with volex, MK, wylex and the series e boards.

To be honest, overall I rate the BG boards and have had very little problems with them, even though lining the busbar up to the devices can be a wee bit irritating! But I have come across much greater obstacles in pursuit of domestic electrical harmony!

 

[OwainDIYer]

I find opening the busbar clamps then pushing them to the back with a non-magnetic tool leaves them stay open to put the busbar in.

 

[JohnW2]

On refitting the bus bar one had to be very careful to ensure the terminals were open it was very easy to get the bus bar below the clamp rather than in the clamp. Laid on it back with original fitting not a problem but once fitted it really needed a special tool to press on all 6 terminal screws to ensure the clamps were open I had to really struggle with a mirror to ensure the bus bar was inserted correctly. ... I am now not surprised there are consumer unit fires it would be so easy for an MCB to be only touching the bus bar rather than clamping onto it and clearly any torque screwdriver would do nothing to redress this problem.

Even in my very limited experience, this is a common problem with many makes of CU.

I am sure other consumer units I have used the bus bars were fixed and the MCB was actually clamped in not by the din rail clip but by the bus bar and if you got terminal clamp wrong side of bus bar the MCB would be lose so easy to detect. Is this just a cheap and nasty consumer unit?

I can't say I've ever seen a CU in which the MCBs etc were not clipped to the DIN rail (hence mechanically fairly well held, regardless of the bus bar connections).

Kind Regards, John

 

[delmel]

BG - Not really noted for quality CU, but some of their things are not bad.

 

[Adam_151]

Some of the better makes, eg merlin gerin. Have the terminals designed so you can't get the wrong side of it. I understand that Wylex may have adopted this in their new range

 

[ericmark]

In the older CU I have used the bus bar was firmly fixed and the DIN rail was only a half DIN rail so it was the bus bar which held the MCB in position so it you missed the bus bar it was very obvious there was an error.

Many did not have DIN rail special slot in MCB's or Plug in. With commercial boards with bus bar up the centre the MCB was fitted other way around I just grabbed a Merlin Gerin and there is no in or out marked and in a board the heating coil is always live.

But in the Merlin Gerin board the bus bars are above the MCB's not below them so always down for off works OK.

I remember one Siemens board where the RCBO switched the opposite way to the MCB. The Bus Bars were vertical but I questioned if I had right parts at the time as having half switched one way and half switched the other was confusing.

Maybe with BG board the MCB's should be mounted down for on? This would remove the problem you could then release one MCB at a time and test it is held on the bus bar before clicking the catch home?

 

[RF Lighting]

I lie on my back under the CU or use a mirror to make sure every cage clamp is actually onto the busbar.

Hager also have the design of clamp where you can not miss the busbar.

 

[RF Lighting]

Hager on the left, MEM on the right. You can see how the busbar hole is completely filled when the clamp is done up, unlike the MEM where the busbar could sit at the wrong side of the clamp.

Untitled

• RF Lighting
• 3 Feb 2015
• 2

 

[kai]

My Wylex unit from 2010 is of the solid fixed busbar format - if a busbar connection is not properly secured, the breaker will simply flop about loose, as its the clamping action of the lower terminal onto the busbar, which secures the breaker into the board.

 

[Taylortwocities]

Hager on the left, MEM on the right. You can see how the busbar hole is completely filled when the clamp is done up, unlike the MEM where the busbar could sit at the wrong side of the clamp.

Another big thumbs up for Hager!

 

[RF Lighting]

I only fit hager or schneider CUs as they're brilliant quality, easy to work with, I never have recalls to failed parts and they have a huge range of accessories.

I don't work for people who try and beat me down on price.