extractor bathroom off shower circuit not light circuit

[kernow]

Bathroom extractor - normally you wire off light - i.e you turn on light and extractor comes on.

In this case the bathroom has much natural light and the light in most cases will not be switched on.

There is no bath so extractor really only needed when shower is used - can a extractor fan be wired into the shower circuit?

 

[ktguk]

best to use a constant trickle humidity fan wired off the lighting circuit. or a fan with a pull cord???

 

[Evans Electric]

You could use a flow detector switch to activate the fan . I don't know of any cases where accessories are conected to a shower , its just bad practice IMO .

 

[SPECIAL LOCATION]

Thought #1

Could use your shower switch supplied via the lighting circuit to switch on the fan and a contactor to power up the shower.

Thought #2

Or a ceiling PIR switch so the fan switches on when someone comes in th room.

Thought #3

Shall I have a beer? Guinness

Thought #4

NO sorry that one is too rude to write!] :Blushing O) :slap

 

[Evans Electric]

Does'nt usually stop you !!!!!

 

[steptoe]

or,

simply put a unswitched fused connection unit between shower pull sw and fan,

I really dont see the big issue,

unless of course you want a time delay,

then you are going to have to employ 2 USFCU,

or something similar.

 

[SPECIAL LOCATION]

Does'nt usually stop you !!!!!

X(

I am affronted Mr E of the VANS!!!!

I will write it down on a post-it note and give it to Brian to bring back when he returns on the bus tomorrow morning...

He says you have been reducing his pocket money & expenses

so he wants me to give him

 

[ianmacd]

or,simply put a unswitched fused connection unit between shower pull sw and fan,

I do. They are only likely rated to 20A and in a fault its likely they will be subjected to double that before the mcb would even think of tripping so they are not fit for purpose.

You could use a flow sensor to detect when the shower is running (i.e. water is flowing though it) and go back to wiring it from the lighting circuit.

 

[steptoe]

And a socket is any different on a 32a MCB?

 

[ianmacd]

And a socket is any different on a 32a MCB?

On a ring it only has to be rated to 20A since thats all the cable needs to be rated to.

 

[steptoe]

Where does that snippet of wisdom come from? I didnt think there was a reg stated that. But there is one that allows the protective device to be downstream.

 

[ianmacd]

Where does that snippet of wisdom come from? I didnt think there was a reg stated that. But there is one that allows the protective device to be downstream.

433.1.5.

So how would there be a downstream protective device if you put the accessory in the middle of a radial circuit between the shower and mcb? What would stop the terminals melting if it consistantly had 45A's across them yet are designed for 20A?

 

[ktguk]

or,simply put a unswitched fused connection unit between shower pull sw and fan,

I do. They are only likely rated to 20A and in a fault its likely they will be subjected to double that before the mcb would even think of tripping so they are not fit for purpose.

You could use a flow sensor to detect when the shower is running (i.e. water is flowing though it) and go back to wiring it from the lighting circuit.

also imagine the tears trying to fit 2 6mm/10mm's into the supply side of a spur

 

[steptoe]

433.2.2

Downstream protection, within 3m .

---------- Post Auto-Merged at 15:14 ---------- Previous post was made at 15:13 ----------

KTG , it can be in 2.5 , or even 1.5 if you so wish.

 

[ianmacd]

433.2.2Downstream protection, within 3m .

---------- Post Auto-Merged at 15:14 ---------- Previous post was made at 15:13 ----------

KTG , it can be in 2.5 , or even 1.5 if you so wish.

So you are suggesting ramming another cable into the shower isolator of a smaller size? So you think that the isolators terminals will have been designed to grip a 10mm and a 1.5mm cable together properly?

 

[Stevie h]

Can you not just wire the fan a double pole switch out side the bathroom , fed off main lighting circuit , if your having a shower , turn in on .

 

[Doc Hudson]

So you are suggesting ramming another cable into the shower isolator of a smaller size? So you think that the isolators terminals will have been designed to grip a 10mm and a 1.5mm cable together properly?

I don't think a 6A MCB terminal is physically any different from a 40A or 50A MCB terminal yet we all seem able to ensure a correct termination and grip with 1.0mm, 1.5mm, 2.5mm, 6.0mm, 10.0mm conductors. Also the earth and neutral bar terminations all use the same size diameter hole and securing screw. Do you not think that providing any termination is big enough for the largest conductor size required, most competent electricians would be able to ensure their joints are mechanically and electrically sound? I would think the problem to be more the reverse, trying to put too large a cable into a small termination.

Doc H.

 

[Andy™]

steptoe - ianmacd does have a point if you put the fused spur between switch and shower (i.e ramming 2x shower cables into fused spur). the 20A part he is refering to is the min cable rating for a ring main. (but his argument falls back down again when you can use a spur on a 4mm 32A radial without problems)

but who would do it that way anyway? easier to use a bit of 2.5 to feed the spur and take it from the output terminals of the shower switch. providing the cable is rated to take the fault current of the MCB (which 1.5 would probably do the job), then its all good. 433.1.3 (iirc, dont have regs to hand) does allow the fused spur to be further into the cable

most shower switches will take a 16mm cable (at a push). so i dont see any problems with adding a 1.5 or 2.5 in there along with a 6 or 10mm cable

---------- Post Auto-Merged at 17:31 ---------- Previous post was made at 17:28 ----------

So you are suggesting ramming another cable into the shower isolator of a smaller size? So you think that the isolators terminals will have been designed to grip a 10mm and a 1.5mm cable together properly?

cant see a problem with it. after all, its just another strand to the 7 already there.

 

[steptoe]

[quote name='Andy

 

[Badger]

Thought #1Could use your shower switch supplied via the lighting circuit to switch on the fan and a contactor to power up the shower.

Thought #2

Or a ceiling PIR switch so the fan switches on when someone comes in th room.

Thought #3

Shall I have a beer? Guinness

Thought #4

NO sorry that one is too rude to write!] :Blushing O) :slap

that would be the way i would personally do the job, as i think thats far safer than trying to stick a small cable on a large mcb!