Illuminated mirror

[GarethH]

I'm have bought an illuminated mirror to replace a shaver socket with. The mirror is heated and has a shaver socket. Its rated power is Max 300W. There's sufficient spare capacity on the circuit.

The manufacturer's instructions says to use 1.5 or 1.75 mm^2 T&E.

The existing cable is all 1.0mm^2.

Any ideas why the instructions say to use 1.5 or 1.75mm^2 cable? I can't see why the existing 1.0mm^2 cable, which is protected by a 3A FCU / RCD (spurred of a 6A circuit), isn't sufficient.

Cheers

 

[timtheenchanter]

if the instructions say yea shall use 1.5, then 1.5 yea must use.

manufacturers instructions must be followed regardless of weather lower specs would be suitable on paper.

 

[GarethH]

I can't disagree re following the instructions. I'd like to know why they specify those cable sizes though.

What the instructions say is:

"Insert a 3-core 1.5 or 1.75mm cable through the pierced hole in the protective cover and thread the cable through from behind the back box into the power supply"

That's the only mention of the cable being 1.5 / 1.75mm^2. If there is a genuine need for larger cable for power reasons (and I can't see how there can be when it's rated at "300W Max") then running a new length of 1.5mm^2 to the mirror would comply with the instructions but leave the remaining cable for that circuit in 1.0mm^2.

I might try ringing the manufacturer and asking them tomorrow.

 

[GarethH]

I guess they might be derating the cable because the mirror is heated...

 

[RF Lighting]

Perhaps

 

[333rocky333]

I can't disagree re following the instructions. I'd like to know why they specify those cable sizes though.

What the instructions say is:

"Insert a 3-core 1.5 or 1.75mm cable

Does 1.75 mm even exist

 

[RF Lighting]

Not that I'm aware of.

I don't think there is a size between 1.5mm² and 2.5mm²

Certainly not a standard size anyway.

 

[333rocky333]

Not that I'm aware of.

I don't think there is a size between 1.5mm² and 2.5mm²

Certainly not a standard size anyway.

Theres a 2mm 2 core, but its not mains voltage mainly for 12 volt use

 

[bernardgreen]

"Insert a 3-core 1.5 or 1.75mm cable through the pierced hole in the protective cover and thread the cable through from behind the back box into the power supply".

"power supply" Is this the 230 volt supply point or a box supplied with the mirror. Could the "power supply" be a transformer supplying the mirror's heater with an isolated and reduced voltage as a safety measure ? If the heater is extra low voltage then current would be higher and voltage drop would be significant in a thin cable.

 

[ban-all-sheds]

Does 1.75 mm even exist

Misprint for 1.25?

 

[GarethH]

"Insert a 3-core 1.5 or 1.75mm cable through the pierced hole in the protective cover and thread the cable through from behind the back box into the power supply".

"power supply" Is this the 230 volt supply point or a box supplied with the mirror. Could the "power supply" be a transformer supplying the mirror's heater with an isolated and reduced voltage as a safety measure ? If the heater is extra low voltage then current would be higher and voltage drop would be significant in a thin cable.

There's no external transformer just a 230V T&E feed through a rubber grommet in the rear of the mirror.

The grommet is the standard type that you pierce so I can't see the cable's outside dimensions making a difference there.

 

[flyingsparks]

I wouldn't worry about using 1mm for a 300 watt load.