power loss @ socket but MCB still on

[Forty4]

Just been to a job where the tenants are saying that a socket in the lounge looses power randomly but does not trip the MCB, it's on a ring so I took all face plates off and checked connections, did IR and got >999 and got continuity on the RFC, 245v and zs 0.39 the problem did not occur while I was there.
They also complained that they had lost 4 microwaves this year but that is plugged into the cooker supply.

Any ideas on where I should look at now would be appreciated.

 

[Marvo]

I also read somewhere that wagos can be used as MF connections but there was a requirement for them to be derated amongst other things. If I can find the info again I'll post a link.

 

[Richard Burns]

I also read somewhere that wagos can be used as MF connections but there was a requirement for them to be derated amongst other things. If I can find the info again I'll post a link.

Certainly the LINE connectors can be used as maintenance free if the 32A are derated to 20A and used in the LINE boxes, they also have an MF cable tie to use for the labelling.

 

[Geordie Spark]

how can you "lose" 4 microwaves? sounds like an insurance scam.

Only a Scouser would think that !!!

 

[keniff]

I think only the lever type wagos are the only actual mf connectors in the range I think I read it off a leaflet that comes in the wago jb box

 

[ferg]

The MF rating for these connectors is fairly recent.
If you check out LINE website you'll see that theirs are MF if derated.

I'd be very surprised if wagos' weren't similar.

 

[DPG]

I don't get why they are only classed as MF if you de-rate them a bit. Surely they are either rated at thate specified current or not. Are they saying that they are only rated at full current if they are available for checking regularly to make sure they haven't burnt out?? Daz

 

[LineProducts]

I don't get why they are only classed as MF if you de-rate them a bit. Surely they are either rated at thate specified current or not. Are they saying that they are only rated at full current if they are available for checking regularly to make sure they haven't burnt out?? Daz

Can of worms here guys!
In simple terms there are two British Standards that have different requirements: BS 60998 specifies Requirements for connectors. BS 5733 specifies requirements for Maintenance Free products. The requirements for BS5733 regarding heat build up/voltage drop are a lot stricter (include testing at twice rating for long periods of time).

This extra requirement makes sense when you consider that Mf relates to inaccessible locations so you want 0 chance (or as close) of failure.

MF was only introduced to BS 7671 with 17 amendment one.Much of the confusion is due to a certain manufacturer promoting their products as MF when they actually meant that you can not carry out maintenance (tighten screws) rather than the new MF which means higher spec for longer life to be used in inaccessible locations.

In answer to your question, it's not that they are expected to burn out at rated current but an effort to minimize any risk that they may.

This is much like an engineer specifying a beam to survive a 1 in 100 year event which in certain circumstances is fine or higher spec to survive a 1 in 1000 yr event.