Lighting on Sockets Circuit Fuse

[oakc]

Starting a new post it's following on from this one:
//www.diynot.com/diy/threads/porch-outside-light-switch-wired-to-sockets-circuit.424852/

basically lights are wired to socket (get live feed from them) and the current switch is a standard on/off switch with a fuse unit and people have kindly explain the need in the other topic.

but i have a new question/query i need help with, think i've found the hardware to use now.

i've got one of these:
http://www.maplin.co.uk/p/lightwaverf-in-line-relay-n64ll

however the fuse in this is 13A and the fuse in the current switch is only 3A... i assume i should replace the 13A with the 3A one BUT they are different sizes?! one in the relay is smaller. why are they different size? just aesthetics or a functional reason?

also as this device is fused - will this still do the same job to protect lighting?

Thanks in advance

P.s. sorry for such a rookie question

 

[oakc]

I tell a lie - closer inspection it says T5A Fuse? is that ok or will i still need a 3A Fuse?

 

[deadshort]

Hi, the 3a fuse in the FCU supplying the light will protect the light and the inline relay.

Regards,

DS

 

[oakc]

sorry DS,

i may have mistaken what i meant i'm looking to replace the switch with FCU for the device above but the device above/inline relay has T5A Fuse, just wanted to make sure the difference in fuse Amps wasn't going to be causing/asking for trouble

 

[Taylortwocities]

The fuse in the Lightwave device is a specific one to protect the device and/or its relay contacts. You do not need to change the value of this fuse.

You will still need a 3A FCU to allow you to connect the lights to the socket circuit.

 

[deadshort]

Hi, sorry got you. You cannot connect the relay to the socket wiring without fusing it down, if the supply was derived from the lighting circuit there would not be a problem.

Regards,

DS

 

[oakc]

the relay has a fuse in it - is this not the same then?

 

[oakc]

if the supply was derived from the lighting circuit there would not be a problem.

Regards,

DS

tell me about it, it's giving me an headache lol

 

[oakc]

ok i understand the difference now the switch with the fuse is a fuse spur lowering the current whereas the fuse in the relay is just to protect the relay not change the current load

 

[EFLImpudence]

ok i understand the difference now

Not quite.

the switch with the fuse is a fuse spur lowering the current

Restricting the current able to be drawn.

whereas the fuse in the relay is just to protect the relay

Yes, but it is possible (likely?) that this fuse will protect the circuit as well.
Have you a diagram?

not change the current load

The load current IS the load current.
The fuse (if correctly selected) will blow IF the load current is too much for the cable.

 

[oakc]

ahh right ok! now i'm torn...

this is what i have in place at the moment
http://www.amazon.co.uk/Electrovision-Switched-Fused-Spur-White/dp/B00GOQY7M6

on the Main side of the switch is the feed (live and neutral) from the plug socket.

on the spur side of the switch plate i have 2 red cables (live from both lamps) and 2 black cables (neutral from both lamps)

my intention was to directly swap this switch with that in-line relay and just put a blank plate on it (then control relay form phone/remote). however my concern is i don't think the fuse in that relay will do the same job as the switch with fuse spur will it?

so with that said i'd have to wire the in-line relay into the circuit and load side of that switch and stowe the relay as there's not enough room in the back box for both relay and switch

 

[EFLImpudence]

my intention was to directly swap this switch with that in-line relay and just put a blank plate on it (then control relay form phone/remote). however my concern is i don't think the fuse in that relay will do the same job as the switch with fuse spur will it?

I don't know. You may be right in which case do what you have in mind.

so with that said i'd have to wire the in-line relay into the circuit and load side of that switch and stowe the relay as there's not enough room in the back box for both relay and switch

Yes.

 

[oakc]

thanks again for the input and guidance, v.much appreciated