Switching a bank of fluorescent fittings

[devonsparky]

Doing a shop fit at the moment and the foreman wants me to put 18 ceiling grid fluorescent on the same switch as there is minimal room in the existing conduit he wants me to re-use.

Would the turning on of 18 fluorescents trip an RCBO ? (Not on loading because it's only drawing 5.6 A on a 10A RCBO.)

 

[smu_diddly]

Just make sure the rcbo is c rated as the current used can be higher in startup just long enough to trip b rated ones

 

[ayjay]

jusy do what forman wants, its not your problem

 

[telectrix]

will almost certainly trip an RCBO, on leakage. a few years ago i has 12 5' doubles on a RCD. it held with 10 and tripped on 12.

 

[Darkwood]

Poor answer smu- How can you assume such an answer is correct without even doing the calc's of which we dont yet know some of the variables also fitting a 'C' type will be reduced your permittent ELI, i hope you dont use this kind of thinking in the real world and do the correct calcs.
Firstly we need to know the wattage and quantity of lamp per fitting
Then the brand of Mcb/ rcbo you intend to use, from this you can check with the manufacturers guides as to starting spikes reletive to mcb in use.
If it is found acceptable to do this make sure your switch is 20amp rated or it will prematurely fail, if the inrush is found to be too large for the mcb regardless of type then contactor(s) should be fitted and either divide over 2 circuits or have a time delayed sequence switching.

 

[devonsparky]

4 x 18w lamps at each fitting.

Reason the foreman wanted them all on one circuit was because he wanted a 2 way key switch near the front door so that the last person out can use the key switch to turn the lights off.

If they were on 2 circuits, it would mean more cable (i.e. - 2 three core & earth for the 2 ways) and as I said, space is limited. - Also, contactors are out of the equation because of costings!

 

[electric will]

Poor answer smu- How can you assume such an answer is correct without even doing the calc's of which we dont yet know some of the variables also fitting a 'C' type will be reduced your permittent ELI, i hope you dont use this kind of thinking in the real world and do the correct calcs.
Firstly we need to know the wattage and quantity of lamp per fitting
Then the brand of Mcb/ rcbo you intend to use, from this you can check with the manufacturers guides as to starting spikes reletive to mcb in use.
If it is found acceptable to do this make sure your switch is 20amp rated or it will prematurely fail, if the inrush is found to be too large for the mcb regardless of type then contactor(s) should be fitted and either divide over 2 circuits or have a time delayed sequence switching.

Could some one advise me on a timed delayed switching device, I take it it'll work with a contractor or relay with a capacitor on the coil side,mis the a off the shelf item? Is the delay time adjustable?

 

[Darkwood]

4 x 18w lamps at each fitting.

Reason the foreman wanted them all on one circuit was because he wanted a 2 way key switch near the front door so that the last person out can use the key switch to turn the lights off.

If they were on 2 circuits, it would mean more cable (i.e. - 2 three core & earth for the 2 ways) and as I said, space is limited. - Also, contactors are out of the equation because of costings!

Technical data Contents
According to Merlin tables you can have 70 x 18watt tubes with compensated standard ballasts on a 10Amp mcb i assume its relating to a type B as it isnt specified so under that thought C would be fine but just require your ELI to comply due to the permitted value been lower.... check the link and browse page 6, note these are not electronic ballasts as the allowances differ for those.
This example is for a multi-9 merlin mcb and different brands have different tolerences so you need to establish it for your own senerio but i would suggest a C would be compliant across the many brands out there as you just 2 lamps over on the above example.

 

[Darkwood]

Could some one advise me on a timed delayed switching device, I take it it'll work with a contractor or relay with a capacitor on the coil side,mis the a off the shelf item? Is the delay time adjustable?

Go to Rs components website and look up Timer relays, there are so any out there its depends exactly what parameters you want, if you require multiple delays i.e. switch several banks on in turn then i would advice a PLC with a simple logic sequence switching program which can be easily learned how to program up in a matter of hours for such an easy task if you've never done one but a laptop and a starter pack are essential to learning them.

 

[ayjay]

just follow what the forman tells u to do- simple-

 

[electric will]

I go by, total wattage, x 1.8 or 2 if doing it in your head ( to allow for start up current) however I do a lot of sho display lighting with led drivers etc and I still find I'm throwing the od breaker as everything on the circuit starts at once. I want to build a delay contractor into the cabinets I wire, so mine tarts just after the original starting current from other displays as gone

 

[electric will]

Go to Rs components website and look up Timer relays, there are so any out there its depends exactly what parameters you want, if you require multiple delays i.e. switch several banks on in turn then i would advice a PLC with a simple logic sequence switching program which can be easily learned how to program up in a matter of hours for such an easy task if you've never done one but a laptop and a starter pack are essential to learning them.

I see eat your saying, I've played about with programmable stuff as a hobby Arduino etc. but I want some thing really simple, might ave a few experiments with a contractor and a capacitor connected to the coil, that should give me a delay shouldn't. It? I know it wont be adjustable.

 

[Rauer]

Why do you need an rcbo in a commercial setting?

 

[worzol99]

As above^^
Worked in many high street chains dont see many lights on rcbo's

 

[Darkwood]

I go by, total wattage, x 1.8 or 2 if doing it in your head ( to allow for start up current) however I do a lot of sho display lighting with led drivers etc and I still find I'm throwing the od breaker as everything on the circuit starts at once. I want to build a delay contractor into the cabinets I wire, so mine tarts just after the original starting current from other displays as gone

Electronic drivers have designed earth leakage and this may be you no'1 enemy if using multiple units (assuming rcd/rcbo protected), manufacturers guidance on leakage needs to be sort and as you give me no quantities this may not even be a concern, if you are throwing mcb's then a little knowledge of the mcb spec's will be needed as well as the loads before designing the circuit if of course u dont implement sequenced starting etc or multiple circuits.

 

[Darkwood]

Why do you need an rcbo in a commercial setting?

Commercial and industrial are still subject to the same Regs as domestic but its more common to see trunking systems and conduit thus no buried cables under plaster so not always needed, OP hasn't given us instal details so couldn't comment on whether its needed.

 

[electric will]

Electronic drivers have designed earth leakage and this may be you no'1 enemy if using multiple units (assuming rcd/rcbo protected), manufacturers guidance on leakage needs to be sort and as you give me no quantities this may not even be a concern, if you are throwing mcb's then a little knowledge of the mcb spec's will be needed as well as the loads before designing the circuit if of course u dont implement sequenced starting etc or multiple circuits.

Most of the circuits are just mcb protected, and my cabinets plug into a 13a wall socket but ran from lighting circuit, I'm trying to make it so I don't have to touch the original shop wiring at all, have my time delayed contractor built into my cabinet, so when the whole shops lights are switched on everything comes on but mind the after say 2 or 3 sec after the delay mine comes on.
up to now I have had to swap the mcb with a c which up to now has been within max Zs, with the timed delay idea i probably wouldn't have to go into the store at all as the unit would just plug in. The normal shop fitters can do that.

 

[Darkwood]

Most of the circuits are just mcb protected, and my cabinets plug into a 13a wall socket but ran from lighting circuit, I'm trying to make it so I don't have to touch the original shop wiring at all, have my time delayed contractor built into my cabinet, so when the whole shops lights are switched on everything comes on but mind the after say 2 or 3 sec after the delay mine comes on.
up to now I have had to swap the mcb with a c which up to now has been within max Zs, with the timed delay idea i probably wouldn't have to go into the store at all as the unit would just plug in. The normal shop fitters can do that.

Simple solution is a on delay relay powered by the lighting circuit switch & N -that closes its relay after the adjustable set time this then lets power through from the plugged in socket to your display, you will have to lable up the unit that it requires isolation at more than one point, also a caution lable on the switch wire as it may energise without notice.

 

[electric will]

I've just ordered a time delay relay and base. My plan is to install it in my cabinets, I'll only have one feed to my cabinet, when this is powered up the timer will start then close the relay then power will go to all the lights in hat cabinet
by this time the original high current from othe lights in the shop should have gone.
no reason why that won't wor is there?

 

[Darkwood]

I've just ordered a time delay relay and base. My plan is to install it in my cabinets, I'll only have one feed to my cabinet, when this is powered up the timer will start then close the relay then power will go to all the lights in hat cabinet
by this time the original high current from othe lights in the shop should have gone.
no reason why that won't wor is there?

Sounds fine as long as you have worked out the original lighting circuit load as you are effectively extending it, and just be careful when ordering time delay relays that u check their function graphs and confirm they operate how you require.... at a guess you want an On delay on energise timer relay but alot out there can be misleading in their title name as different brands can share names and give different funtions.