Pictures 'cause it's Friday

[BS3036]

Guy sitting next to our CU at work yesterday complained it was buzzing. Determined it was one of the (fluorescent) lighting circuits (second from right in CU picture), and found it was carrying 6.3 A with a clamp meter, and has been doing so for the last 15 years. Received replacement MCB in post today, and took out the old one. (Also removed some luminaires from the circuit.)

So this is the result of a 5% overload for 15 years. (I know you've all seen it before, but it surprised me.)

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• BS3036
• 5 Jun 2009
• 1

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• BS3036
• 5 Jun 2009
• 1

Untitled

• BS3036
• 5 Jun 2009
• 1

Untitled

• BS3036
• 5 Jun 2009
• 1

There is at least one funny in the CU to spot. I'll expain if anyone is interested.

 

[RF Lighting]

It's switched on with the busbar shroud missing?

Was the adjacent MCB damaged too?

 

[ricicle]

2.5mm² in a 6A MCB ?

Was there a VD issue ?

 

[RF Lighting]

Nothing wrong with that though

 

[ricicle]

Nothing wrong with that though

No, but there must be a reason for it...............

 

[EdwardCurrent]

? No 30mA protection for skts used by 'ordinary' people ?


Ed

 

[RF Lighting]

Looking at the age of the CU, that probably wasn't a regulation when it was installed.

 

[jockspark]

6.3 amp on the clamp meter don't think the start up
current done it much good

 

[ricicle]

Looking at the age of the CU, that probably wasn't a regulation when it was installed.

I was installing 'Starbreakers' back in the late 80's as an apprentice (15th Ed.)

 

[BS3036]

It's switched on with the busbar shroud missing?

That's a valid point - This CU has never had a shroud - is that normal for a 22 year old Crabtree? Slap wrist, but the cover was just removed carefully for the photo.

Was the adjacent MCB damaged too?

It didn't seem to be visibly affected. Hard to test an MCB.

2.5mm² in a 6A MCB ?

Was there a VD issue ?

That was the main point I had in mind. It seems that there was a need, many years ago, for a supply to a mercury box (if anyone remembers those). There was a 13A socket fitted just below the CU (where the phone line also comes in). The socket had a label 'No Kettles, etc'. I removed it today. I'm not sure why the lighting circuit was chosen, though.

No 30mA protection for skts used by 'ordinary' people

Looking at the age of the CU, that probably wasn't a regulation when it was installed.

I think that's the case (around 22 years ago). Everyone in the company was also an electronic engineer so I suppose could be 'skilled' or 'instructed' anyway. (?)

6.3 amp on the clamp meter don't think the start up
current done it much good

Maybe but I don't believe that 1 second or less, once a day, did that. I'd rather believe that my uncalibrated clamp meter is some way off!

 

[RF Lighting]

I remember fitting BSEN60898 MCBs as an apprentice about 12 years ago, so it's older than that.

 

[JohnD]

the busbar doesn't seem to have any supports, is that right? and it is unshrouded too, unless you removed a cover to work.

It looks as if it has steel brackets bolted to it, can't quite see how its done. Is that unusual in the old model of Starbreaker? It's not how I remember them.

 

[RF Lighting]

The busbar is held by the black plastic bit screwed to the end of the din rail chassis jobbie. It just looks to be floating in that photo.

There should be a busbar shroud, which is missing.

 

[securespark]

Looking at the age of the CU, that probably wasn't a regulation when it was installed.

I was installing 'Starbreakers' back in the late 80's as an apprentice (15th Ed.)

1987 was my first Starbreaker install - just like the board in the piccy.