Multiple bath room switches.

[stevenbouf]

Hello everyone My names Steve and I'm an electrician from RI. My problem is I have a building I'm wiring with four bath rooms and one common exhaust fan remotely mounted. Now how can I be able to control this fan from each bathroom by motion. Im not sure if these motion sensors can be linked to control a relay. Or maybe four single pole motion switches wired in parallel to a relay coil but wouldn't the activated switch back feed the other switches. Does that even matter. Also all the bath rooms will have motion switches to control there individual lights. Of coarse im trying to keep the cost down there has to be a way without some expensive control panel. Thank you.

 

[Smart $]

Hello everyone My names Steve and I'm an electrician from RI. My problem is I have a building I'm wiring with four bath rooms and one common exhaust fan remotely mounted. Now how can I be able to control this fan from each bathroom by motion. Im not sure if these motion sensors can be linked to control a relay. Or maybe four single pole motion switches wired in parallel to a relay coil but wouldn't the activated switch back feed the other switches. Does that even matter. Also all the bath rooms will have motion switches to control there individual lights. Of coarse im trying to keep the cost down there has to be a way without some expensive control panel. Thank you.

Use occupancy sensor switches (rated for HP) wired in parallel, but not the same ones as the lights. Could be the same ones as the lights if they are 2-pole switches, but they are generally more expensive than two 1-pole (though installation costs may balance out).

 

[Dennis Alwon]

I have wired motion sensors for driveway lights that were wired like 3 way switches. I fed the first sensor and then went with a 3 wire cable to each light over to the next sensor. Either sensor would activate the lights.

 

[stevenbouf]

Use occupancy sensor switches (rated for HP) wired in parallel, but not the same ones as the lights. Could be the same ones as the lights if they are 2-pole switches, but they are generally more expensive than two 1-pole (though installation costs may balance out).

My concern would be that the switch thats activated would be backfeeding the other three switchs

 

[stevenbouf]

I have wired motion sensors for driveway lights that were wired like 3 way switches. I fed the first sensor and then went with a 3 wire cable to each light over to the next sensor. Either sensor would activate the lights.

Same problem of back feeding other sensors.

 

[Dennis Alwon]

Same problem of back feeding other sensors.

I am saying it is not an issue. I have done it often

 

[Smart $]

My concern would be that the switch thats activated would be backfeeding the other three switchs

As long it isn't the same switch or pole as the individual lighting circuits, it's not an issue.

 

[G._S._Ohm]

four bath rooms and one common exhaust fan remotely mounted.
how can I be able to control this fan from each bathroom

One equivalent circuit that will work is that the fan is controlled by an AC relay with a DC coil and each motion sensor feeds the anode of a diode. Logically, it is a "wired-or" circuit.

 

[Speshulk]

If the individual switch controlled a motorized damper with an end switch for the duct work connected to that particular bathroom, there'd be no back feed and the ventilation system would function better. You'll suck the fart out of the bathroom that's actually occupied if the fan isn't drawing air from 3 other bathrooms at the same time.

 

[Speshulk]

Just curious: why would you want the fan to come on every time someone walked into a bathroom?

 

[Little Bill]

Just curious: why would you want the fan to come on every time someone walked into a bathroom?

Many commercial/industrial places want or require the fans to be on when the lights are on.

 

[G._S._Ohm]

People who don't flush toilets may be proud of what their body produced, just like infants who are learning toilet training.
Somewhat less Freudian, these inconsiderate people may be marking their territory with the smell, just like dogs peeing.
With the fans in parallel with the lights they have to decide whether they want to mark their territory in the dark.

 

[kwired]

Just curious: why would you want the fan to come on every time someone walked into a bathroom?

If you want to ensure the fan gets turned on, do you have a method that it much better? When the room is in use the fan is on. If you leave it up to the user to turn the fan on, some may turn it on, most probably will not.

If the individual switch controlled a motorized damper with an end switch for the duct work connected to that particular bathroom, there'd be no back feed and the ventilation system would function better. You'll suck the fart out of the bathroom that's actually occupied if the fan isn't drawing air from 3 other bathrooms at the same time.

Especially on a dwelling, why bother with all that extra equipment and expense - just put in individual fans for each room, it will cost less, and be simpler to maintain.

My concern would be that the switch thats activated would be backfeeding the other three switchs

Any other control arrangement with OR logic will put switches in parallel to each other at some point in the control circuit also.

If you back feed the switch via another you simply have a voltage of zero across all the switches (disregarding any minimal contact resistance), that is not going to hurt anything.

 

[480sparky]

In any application where one fan motor serves two or more rooms, I just use 2-pole switches in each room.

 

[kwired]

In any application where one fan motor serves two or more rooms, I just use 2-pole switches in each room.

OP wants to use occupancy sensors to turn the fan on. Doesn't change most of the concept involved, but he either needs double pole occupancy sensors, or separate sensors for lights and fans, or use relays driven from lights to drive the fan.

 

[jeremysterling]

In any application where one fan motor serves two or more rooms, I just use 2-pole switches in each room.

The UK wiring thread may be worth revisiting. I like the install, however, it sure looks like parallel conductors to me.

 

[kwired]

The UK wiring thread may be worth revisiting. I like the install, however, it sure looks like parallel conductors to me.

There is not a "parallel" conductor in that drawing. There are conductors that are parallel to other conductors, but not necessarily carrying same current as the conductor they are parallel to.

The issue of what "parallel" conductors are not allowed by the NEC involves conductors that are physically joined together at each end, and the primary intent is to create an effective "single conductor" out of multiple conductors that alone would not have same characteristics (primarily ampacity) as the effective single conductor has.

All parallels in that drawing are not connected together in a way to effectively make a larger ampacity conductor, the parallel paths in that drawing have a different purpose.

 

[480sparky]

The UK wiring thread may be worth revisiting. I like the install, however, it sure looks like parallel conductors to me.

The lines may be drawn in parallel, but they are not parellel in an electrical appliction. Could you point out the two conductors that have the same point of terminations at each end?

 

[jeremysterling]

The lines may be drawn in parallel, but they are not parellel in an electrical appliction. Could you point out the two conductors that have the same point of terminations at each end?

As in the UK wiring "ring circuit" thread, there is an obvious debate here. Your design has merit as does the ring circuit.

I think the code intent is to avoid this type of install, as indicated by an exception that allows control wiring to be parallel with spelled out requirements. As with a "ring circuit", there is not absolute guidance on this install.

The OP can avoid this with his relays, because there is an exception for parallel conductors for control as long as the conductors meet the requirements of the exception in 310.4(A).

 

[kwired]

As in the UK wiring "ring circuit" thread, there is an obvious debate here. Your design has merit as does the ring circuit.

I think the code intent is to avoid this type of install, as indicated by an exception that allows control wiring to be parallel with spelled out requirements. As with a "ring circuit", there is not absolute guidance on this install.

The OP can avoid this with his relays, because there is an exception for parallel conductors for control as long as the conductors meet the requirements of the exception in 310.4(A).

relays or wall switches, there is still switches in parallel. That is not the same thing as parallel conductors, and there is no intent here or in the ring circuit to attempt to make one larger conductor out of two or more smaller ones.