3 core and earth flex - should I use both live cores?

[Emtoucan]

Hi,

I'm going to hardwire my boiler into a FCU.

The plug has already been cut off and the flex is 3 core and earth. How should this be wired? I assuming that as it has the extra core it should be used?

I'm also presumming that it's OK to use a 13amp FCU if I change the fuse to a 3amp?

Thanks

 

[stardanny]

What Boiler is it? What system is it?

 

[securespark]

There is at least one crucial question you should be asking yourself. The first is,

How was the plug wired up?

 

[Emtoucan]

How was the plug wired up?

Unfortuately it had been taken off before I got to it.

I've had a look in the boiler manual and when referring to the electrical installation it only mentions a live (brown or red) and a neutral (black or blue) connections. There is no mention of anything else apart from the earth.

Therefore I thinking brown for live, blue for neutral and leave the black redundant.

 

[Emtoucan]

What Boiler is it? What system is it?

It's a combination boiler and the made worcester.

 

[gasandoilman]

With a combi boiler you only need a live n and earth 3 wires
Other boilers may need 4 wires 4 a pump over run

you should have a room stat wired to the boiler to be part p

 

[securespark]

If the black is redundant, it good practice is for it to be grounded.

Why can't you access the other end of the flex to see how it has been terminated?

 

[ColJack]

you should have a room stat wired to the boiler to be part p

and another false Part P legend is born...

where does it say that???

 

[Emtoucan]

you should have a room stat wired to the boiler to be part p

There is a room stat in the hallway.

The instructions state

"The connection to the mains nust either be: A 3amp fused 3 pin plug and unswitched socket outlet or a double pole isolator with a contact seperation of 3mm in both poles and supplying the appliance and controls only."

I take it a switched FCU is classed as a DP isolator?

 

[ColJack]

some are, some aren't...

 

[Emtoucan]

Looking on screwfix it definately says that the switched FCU is double pole

 

[gasandoilman]

sorry part L building regs say you should have a room stat

 

[gasandoilman]

why not wire in a 3 core flex to l.n.e with a plug 3amp fuse
job done

 

[ColJack]

do they do a book on the building regs? like the regs book for electrics?

 

[gasandoilman]

yes worst part of the course is the regs acs(corgi)