Steeple consumer unit mounting rail

[Kes]

About five years ago my garage was extended and rewired. The contractors fitted a metal 8-way Steeple cu to feed power and lights with Steeple rcd and Series E mcb's. Yesterday I opened the cover for a look and found that the rcd/mcb mounting rail was not the usual fairly narrow din rail with flanges top and bottom but a much wider plate with the top angled forwards a little, on which the mcb's hung. They had no apparent fixing at the bottom of the mcb's.

How are the mcb's fastened to the rail? I couldn't see any obvious way but they appeared to be firmly fixed. Are the mcb's a specific type to suit this rail or can other makes be fitted? I know the Steeple brand is Denhams and probably used for price, but why don't they use the standard din rail?

 

[sparkwright]

Don't know for sure what you have, but some 'plug' into a special busbar.

There is a catch at the bottom of the mcb which gets pulled, and the mcb can be pulled out.

This method is one of the Crabtree types, it may well be similar to your Steeple range.

 

[Taylortwocities]

Photos please!

 

[Kes]

I'll try...

Untitled

• Kes
• 2 Mar 2014
• 1

 

[sparkwright]

Not plug in then.

What actually is the problem then?

The MCBs hang on the din rail and the busbar is connected to the bottom terminals.

No shield on the busbar.

On some boards, you have to remove the busbar to remove an MCB.

 

[Kes]

No problem, just the eternal quest for knowledge.

I find it hard to believe that the mcb's just hang loosely on the rail. In fact they are firmly fixed in some way, as they can't be moved manually in any direction. Perhaps it's the plastic clip holding the busbar, or the neutral bar.

There is a plastic angle strip that fits into the plastic clip and shields the busbar and lower part of the mcb's, quite flimsy.

 

[Taylortwocities]

As Sparwright says, they are screwed to the busbar. Loosen off the bottom screw and they'll lift off.

PS, that is the LIVE busbar, not the neutral. That bare copper is all 230V.
You should have turned off the power before removing the cover……..

 

[Kes]

I did. Thanks for all your help.

 

[JohnW2]

As Sparwright says, they are screwed to the busbar. Loosen off the bottom screw and they'll lift off. ... PS, that is the LIVE busbar, not the neutral. That bare copper is all 230V.

I suspect that the OP realised that but was suggesting (I think correctly) that the only thing actually mechanically 'restraining' the MCBs (and RCD) was the RCD's connection to the neutral bar (which is presumably attached to the casing). Remove that little 'neutral busbar' and the RCD plus MCBs would, as far as I can see, be 'flapping about in the breeze' (albeit as a single unit), just dangling from the upper rail.

I must say that I was brought up with the notion that, at least generally, electrical conductors should not be used as the sole means of mechanical attachment/restraint.

Kind Regards, John

 

[EFLImpudence]

They will be restrained by the cover - metal.

 

[Spark123]

Looks like a GE (General Electric) consumer unit rebranded as Steeple.

 

[JohnW2]

They will be restrained by the cover - metal.

True (when the cover is on), but it still seems a little surprising to me - I guess just due to my lack of experience/exposure to such things.

I presume that one of the main reasons for my 'unbringing' is that if screwed electrical connections form at least part of the mechanical attachment, then mechanical stresses (e.g. due to operating the MCB lever) might gradually loosen the electrical connections.

Kind Regards, John

 

[AndyPRK]

See those square cuts outs at the bottom.

The Mcbs probably clip into those.
Can't see cus of the busbar

 

[Taylortwocities]

Maybe..

Turn the power off again, remove the live busbar.
At the bottom of each MCB there will be a small lever arrangement, This secures the MCB into those square cutouts with the groove at 12 o'clock.
Pull down the lever and the MCB should pull forward from teh bottom end.

 

[JohnW2]

See those square cuts outs at the bottom. The Mcbs probably clip into those. Can't see cus of the busbar

I wondered about them, but since they appear to be below the very bottom of the MCB casings, it seemed unlikely (although obviously not impossible) - we'd obviously need to see it without the busbar to be sure. I certainly would remain 'surprised' if there is no proper mechanical restraint at the bottom (other than the screwed electrical connections).

Kind Regards, John