External metering enclosure

Martin Kerr · Mar 28, 2019

Folks
Could you suggest an fused isolator of choice, to install in a recessed external metering cubicle, in a domestic installation, this will be required to terminate a 25mm SWA
I am unsure of how much space I can utilise of the standard enclosure, not to encroach on the DNO cut-out and meter installation

Martin Kerr · Mar 30, 2019

Quick update folks
Called into DNO head office and was able to establish they would accept, an isolation device located tight against the right-hand side, but didn't confirm what space they would be willing to sacrifice, which brings me back to the original question
What switch fuse would be suitable to terminate a 3 core 25mm swa in a small footprint as the cubicle is only 400mm wide
And needs to house the DNO cut out and also

freddo · Mar 30, 2019

I used one of the crappy metal Lewden 100A switch fuses last time (not my choice!), fitted tight to the bottom right. The meter box was surface mounted with the armour cable sticking out the bottom, though there will be room for the cable to enter the top right of the swfuse if you need to. This left plenty of room for the cutout on the left and loads of room above for meter.

Toneyz · Mar 30, 2019

Usually, there is room top right but there is not a lot of room for bending radius for the SWA, therefore, the SWA would need to be made off and slack pushed back. I have not installed any of the new metal switch fuses but the Wylex one seems to look ok I always take into consideration room inside the switch fuse to make off and forming of the 25mm tails as they are sheathed.

Taylortwocities · Mar 30, 2019

Wylex switchfuse
Dimensions on the link

freddo · Mar 30, 2019

Those are nice switchfuses, except the terminal screws are too small for the terminals.

Charlie_ · Mar 30, 2019

Instead of an isolator why not a dp MCB in an enclosure?

Toneyz · Mar 30, 2019

freddo said:
Those are nice switchfuses, except the terminal screws are too small for the terminals.

What do you mean they are too small for the terminals?

Taylortwocities · Mar 30, 2019

Charlie_ said:
Instead of an isolator why not a dp MCB in an enclosure?

MCB not the best choice for this sort of application.
It’s very hard to get discrimination if the downstream device is also an MCB.
Fuse, all day long…

Toneyz · Mar 30, 2019

Charlie_ said:
Instead of an isolator why not a dp MCB in an enclosure?

It gives bad discrimination ( selectivity for all you 18th's out there)

DefyG · Mar 30, 2019

Never had an issue with installing a SF in a metering enclosure as long as the equipment doesn't interfere with the cutout or meter.
If I remember correctly, the Lewden SF accepts upto 35sqmm! and is quite sturdy and relatively small.
The Wylex equivalent SF is often too big to fit in.

freddo · Mar 30, 2019

anthonybragg said:
What do you mean they are too small for the terminals?

See this post here.

freddo · Mar 30, 2019

freddo said:
Those are nice switchfuses, except the terminal screws are too small for the terminals.

I just looked again, it really is pretty poor, small steel allen screws in a brass terminal. They should be large brass slotted screws in brass terminals. What garbage.