Old MK Sentry and RCBOs ?

[Moley]

In our workshop/stores unit we've got an old MK Sentry CU with no RCD. The work benches all have RCD sockets. I'm planning on putting in a new radial for the washing machine and wondered if a current RCBO would fit in the old CU or if a RCD socket would be the only way forward.

It's a nice size unit. Can get 4 Transits in with ease and only 2 of us that ever use the unit, and I'm mainly there to work on my own stuff Now that I've fixed our donated washing machine (pump bearings worn) it should stop my own washing machine from smelling of transformer oil.

 

[James]

Could you install a fused connection unit instead of a socket?
Rcd might not be required.

If it is definitely needed, I might have one kicking about, just let me know and I will search for it.
And No, the new ones don’t fit the old boards.

 

[Moley]

If the RCBOs won't fit and I would like the washing machine on a RCD I might just fit a fcu to the ring and a RCD socket. It'll save me running a fairly long radial and conduit around the workshop.

 

[Pretty Mouth]

I asked circpro about backward compatibility:

Me:

A customer has an old plastic split load consumer unit containing MK sentry MCBs and an RCCB. I would like to replace some of these devices and would appreciate your advice on compatibility.

Is it ok to replace the existing LN5760S RCCB with a H5660S?
Is it ok to replace an existing LN5932S MCB with a H7736M RCBO?


Circpro:

CircPro (UK) Ltd have been supplying MK circuit protection to the UK market since mid-2020. All the consumer units supplied by CircPro are metal enclosures (as per wiring regulation amendments – 17th edition).

Metal consumer units supplied by MK/Honeywell after 2017 will be of the same metal design/construction. For older consumer units including plastic units, we are unable to supply spares.

Similarly, device design will have changed over the years, it is not possible to age the device listed (15+ years old?) and hence we are unable to confirm that the current RCD will be a direct replacement, but ‘LN’ series is noy likely.


Not massively helpful. In the end, I installed the devices anyway. They fitted well on the din rain, the only sight issue being the lower terminal on the RCBO is slightly shallower than those of the neighbouring MCBs. I trimmed a couple of mm off the one busbar tooth to allow for this, and it all fitted together nicely. Yes, I do know this is non compliant, and by many's standards, a bodge.

 

[brianmoooore]

Yes, I do know this is non compliant, and by many's standards, a bodge.

If you have used your engineering judgement in doing this and consider it to be OK, then in my opinion it is OK.

 

[littlespark]

I’ve just replied to another thread about old mk rcbo’s, and this thread was a “similar” at the bottom.

I’ve got an old sentry RCBO if you’re still looking.