Yet another bathroom fan question!

[Juggernaut]

Hi all - I'm planning on installing a bathroom fan as described in the wiki at...

//wiki.diynot.com/electrics:lighting:fan

It's the circuit diagram below that I intend to use

The main difference is that I intend to use a 2 gang switch in the hall, instead of the DP pull switch in the bathroom.

My first questions is where can the SFCU be placed? For asthetic reasons my preference would be to place it in attic above the bathroom (where the junction box will be going). Is this ok? I appreciate that it isn't so easy to replace the fuse in this case...

The next option is to mount it on the wall near the fan (in zone 3). I assume this is ok - every office toilet seems to have one for the hand-dryer...

My next question is how is the earthing at the switch done? The diagram suggests that the switch is earthed on the feed side, but not on the fused fan side. In practice, I assume this would mean two T+E cables going to the switch, one of which earths and one of which doesn't. This makes sense given that the aim is to be able to isolate the earth on the fan side of the SFCU, but I just wanted to check my understanding. I have to admit, my understanding of an earth was that it was universal, but the circuit diagram suggests that when you turn off the SFCU the fan is no longer earthed...

Thanks

J

 

[empip]

A correction is required to the dwg.
There is an earth missing twixt pull cord and the connections before the fan proper... this should be shown.

At the Double Pole Switched Fused Connection Unit, Live and Neutral are switched. Do not confuse with triple pole isolator which switches
Live : Switched live : Neutral. and would appear just before the fan in the dwg...
AFAIK the Earth continues to the point at which it is no longer required (double insulated fan unit ) then is safely terminated.

 

[Juggernaut]

Ok, so you're saying that the SFCU does not break the ground connection between the feed and load side when switched off, and that there should indeed be a ground connection between the switch and the junction box just before the fan? That certainly makes more sense to me...

Thanks!

J

 

[empip]

Wiki updated.

Just slapped a length of cpc into Plugs sketch

 

[Juggernaut]

Thanks for that!

Can anyone tell me where the SFCU (or triple pole isolatorm, if one uses that approach) is normally fitted relative to the fan?

 

[securespark]

Some fan manufacturers request their fans are fused down, but most are happy with a fan on a 5/6A circuit without it.

As for TP isolators, all timer fans should have one for maintenance purposes.

 

[Juggernaut]

If I go with the triple-pole isolator, I assume that the SFCU shown in the diagram can be replaced with a simple fused connection box (should the manufacturer require the fan to be fused). Correct?

Where do people recommend playing the triple-pole isolator? On the wall beside the fan (zone 3), or would you put it out in the hall where the bathroom light-swith is?

Thanks

J

 

[bernardgreen]

Where do people recommend playing the triple-pole isolator?

Almost always placed over the bathroom door outside the bathroom. It needs to accessible but ""out of reach to prevent the fan being accidently turned off"".

 

[twitchy]

What is the tidy way to deal when two required.

The bathroom has been split into two parts, shower room and bathroom. Both have own light and own fan from separate switches. Shower room out in hallway , bathroom using pullcord, in the room. Existing TP switch is outside in hallway and was going to put fcu next to it. For other ( new ) fan which will be operated by separate light switch, should i locate new TP and FCU in hallway next to exisiting one?