Hager meter kit fusing stupidity

pc1966 · Jun 18, 2020

Today we got our Hager meter kit for one of their 125A TPN boards. It has a little DIN rail fuse holder as the meter is powered right off the incoming isolator/RCD/etc without any MCB for protection (so the meter can't be switched off without everything going off, presumably so you don't cheat on any internal billing but that means).

So I opened it up to look at the fuses and was rather shocked to see a 0.5A glass LRC fuse! You know, the sort with a breaking capacity of 35A at 250V AC! This is off a 400V TPN board that could have a 10kA fault current at that point FFS!

Even replacing the fuse with a 20x5mm HRC fuse is only good to 1.5kA fault rating. What were the product designers thinking?!

Lucien Nunes · Jun 18, 2020

Type-tested assembly...the fuse shatters but the box keeps the debris contained?
The meter protects the fuse?
Design specified HRC but stores had run out?
Counterfeit switchgear, meter module actually just contains sawdust?

Dunno, sounds carp anyway.

pc1966 · Jun 18, 2020

Lucien Nunes said:
Design specified HRC but stores had run out?

That was what crossed my mind at first.

freddo · Jun 18, 2020

LOL it would probably all arc together across the fuse holders if there was a serous fault in the meter module, you could test it out to see what happens? Slydlok FTW!

radiohead · Jun 18, 2020

On a similar theme, one well known gas boiler (cant remember which) used to have a fuse on both the line and neutral incoming connections. Could never work out why they thought that was a good idea.

static zap · Jun 20, 2020

radiohead said:
. Could never work out why they thought that was a good idea.

..Only qualified should access ..
--who occasionally get polarity wrong ! anyway .--
(external power getting switched to neutral ?)

davesparks · Jun 20, 2020

radiohead said:
On a similar theme, one well known gas boiler (cant remember which) used to have a fuse on both the line and neutral incoming connections. Could never work out why they thought that was a good idea.

Probably designed for another EU country where it is a requirement and they didn't get the UK variant right.