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Electrician's help needed Urgently!

TokeMcLeod

New Member
My plants are ready to go into the flowering room, but I have not yet completed the wiring. Stealth purposes prevent me from asking for advice from local electricians and supply shops.

I need help with a few items, please

Allow me to describe my set-up:

220V supply
New circuit breaker to be added in to existing DB

Inside the room:
Digital timer
Contactor

A total of 56 1,5m T5 double fittings
58W Warm white tubes (112 total)
(These are assembled into 8 panels of 7 fittings each, each panel with a switch)

One 8 inch inline extractor fan (two-speed)

Two 10" oscillating fans

One space heater, max power 400W, thermostat controlled

When the timer signals on, I'd like all the lights, the oscillating fans and the extractor fan to come on (at the high speed setting).
The heater to be powered continuously
Timer signal off should turn off all equipment, but power the extractor fan at the low speed setting.

My questions are:
What size and type of contactor should I be using?
How do I wire the contactor to fan?
What size wire do I need for a) DB to contactor (24ft); b) Size of circuit breaker needed in my existing DB to supply this; c) Wire size from contactor to switch on each of the 8 light panels (The panels will be in two adjacent rows of 4 each, with the contactor mounted against the one end wall of the room. The output will thus be split at the contactor, supplying two sets of 4 panels each and one supply to the fan. Maximum distance about 18ft.

This is urgent, so if an electrician reads this- PLEASE HELP!
 

boobylover

New Member
112
My timer is rated 20A

So a conservative estimate on load is around 7500 watts including your heater and misc. items. You mentioned 220 volts power supply so using that number we get a 34 amp requirement. This means you'll need a double 40 amp breaker and #8 wire from panel to contactor. Your timer will serve as pilot duty only, meaning its contacts will only switch the contactor coil, not the load. You'll want a 40 amp rated DPST contactor for switching the lights. I'd personally split the banks of lights into groups of three using #14 wire with a 15 amp fuse for each feed. The fusing protects the wire, not the components. Also if your going to have pumps/sprayers in the vicinity of all this electrical, you'll need to get some GFCI outlets and power the load through that device so you have ground fault protection. This is gonna be an all weekend job. :)
 

TokeMcLeod

New Member
So a conservative estimate on load is around 7500 watts including your heater and misc. items. You mentioned 220 volts power supply so using that number we get a 34 amp requirement. This means you'll need a double 40 amp breaker and #8 wire from panel to contactor. Your timer will serve as pilot duty only, meaning its contacts will only switch the contactor coil, not the load. You'll want a 40 amp rated DPST contactor for switching the lights. I'd personally split the banks of lights into groups of three using #14 wire with a 15 amp fuse for each feed. The fusing protects the wire, not the components. Also if your going to have pumps/sprayers in the vicinity of all this electrical, you'll need to get some GFCI outlets and power the load through that device so you have ground fault protection. This is gonna be an all weekend job. :)

Thank you booby! You're a lifesaver.

Can you please clarify a few points for me:
1) Why a double breaker? (Will a single 40A not work?)
2) What is a "DPST" contactor?
3) How to wire the contactor to the two-speed fan, so I get the switching between the two speeds as set out in my post above?
4) What is a GFCI outlet?
5) Local systems don't use fuses- only breakers. Will two feeds to the banks of lights through 20A breakers be OK?
6) The wire sizes you mention- are those AWG? (Local sizes are metric and I'll need to convert)

Yeah- this is more like into early next week job...I'm working cautiously, given my lack of electrical knowledge.
 

boobylover

New Member
Thank you booby! You're a lifesaver.

Can you please clarify a few points for me:
1) Why a double breaker? (Will a single 40A not work?)
2) What is a "DPST" contactor?
3) How to wire the contactor to the two-speed fan, so I get the switching between the two speeds as set out in my post above?
4) What is a GFCI outlet?
5) Local systems don't use fuses- only breakers. Will two feeds to the banks of lights through 20A breakers be OK?
6) The wire sizes you mention- are those AWG? (Local sizes are metric and I'll need to convert)

Yeah- this is more like into early next week job...I'm working cautiously, given my lack of electrical knowledge.

Here is a fuse block holder that will accept up to 30 amp fuses;
Mersen Ferraz Shawmut 20307R Fuseholder | eBay

As for the 2 speed fan, you would need a separate relay to do that, and the lighting timer would also energize that coil, and the hi speed circuit. SPDT. Single pole double throw.

Yes two feeds at 20 amps will work however you'll need to upsize the wire to #12

A 2 pole breaker because with 220 volts you have two hot lines which need to be protected. (unless you're in Europe where there is no 115 volt supply)?

A GFCI outlet has internal ground fault protection that's used for wet areas.

A DPST contactor is a relay that switches 2 circuits ON/OFF only. There is no normally closed circuit.
 

TokeMcLeod

New Member
Here is a fuse block holder that will accept up to 30 amp fuses;
Mersen Ferraz Shawmut 20307R Fuseholder | eBay

As for the 2 speed fan, you would need a separate relay to do that, and the lighting timer would also energize that coil, and the hi speed circuit. SPDT. Single pole double throw.

Yes two feeds at 20 amps will work however you'll need to upsize the wire to #12

A 2 pole breaker because with 220 volts you have two hot lines which need to be protected. (unless you're in Europe where there is no 115 volt supply)?

A GFCI outlet has internal ground fault protection that's used for wet areas.

A DPST contactor is a relay that switches 2 circuits ON/OFF only. There is no normally closed circuit.

I am in southern Africa where domestic supply systems are all 220V, single phase. I'd guess that our systems are closer to European systems than US.

Standard installation in any DB first routes the supply through an Earth leakage unit (example here: Earth Leakage Unit). I think this provides much the same protection as the GFCI outlet you mention, but at the supply entry to the DB. (GFCI's are certainly not standard/normal here. In fact, I've never seen one.)

About the fan: My timer (electronic with battery back-up) has only a single output, so when it signals 'on' it can power the fan at the high setting. When the timer signals 'off' it has no output....how then to supply the low speed fan during the dark cycle?
Is it not possible to use a single contactor, that when not energised will supply the low speed and when energised will supply the high speed?

I found this old entry on Yahoo answers:
Consider a double throw single pole (DTSP) relay. There are 5 electrical connections on such a device. Double throw means the switch has both a N.O. & N.C while a Single throw will be either one.

1.Coil
2.Coil
3. N.O.
4. Common
5 N.C

The position of the contacts when the coil is de-energized is used to define their state as being either Normally Open (N.O.) or Normally Close(N.C.)

For your fan example lets assume a DC fan and a small buzzer. The fan and buzzer negative wires will get connected to the negative of the DC power supply . The relay will control the switching of the positive voltage to either the fan or the buzzer The positive DC would get connected to the Common. The fan is connected to the normally open and the buzzer is connected to teh normally closed.

With the relay in its normal de-energized state the buzzer will be sounding and the fan will be off. Energize the relay coil and the recontacts will shift position causing the buzzer to silence and the fan to start.


Would this work for my installation?

Thank you for the wire size and breaker info...job in progress as you read this :thumb:

(Now only still need to figure out the fan supply/control and I'm good to get the job done, move the girls in and harvest my Exodus Cheese clones in about 9 weeks...this is my first indoor grow, so quite a learning curve but enjoying it immensely and getting there...my 36 veg'd plants are super-healthy and happy:love:).
 

boobylover

New Member
I am in southern Africa where domestic supply systems are all 220V, single phase. I'd guess that our systems are closer to European systems than US.

Standard installation in any DB first routes the supply through an Earth leakage unit (example here: Earth Leakage Unit). I think this provides much the same protection as the GFCI outlet you mention, but at the supply entry to the DB. (GFCI's are certainly not standard/normal here. In fact, I've never seen one.)

About the fan: My timer (electronic with battery back-up) has only a single output, so when it signals 'on' it can power the fan at the high setting. When the timer signals 'off' it has no output....how then to supply the low speed fan during the dark cycle?
Is it not possible to use a single contactor, that when not energised will supply the low speed and when energised will supply the high speed?

I found this old entry on Yahoo answers:
Consider a double throw single pole (DTSP) relay. There are 5 electrical connections on such a device. Double throw means the switch has both a N.O. & N.C while a Single throw will be either one.

1.Coil
2.Coil
3. N.O.
4. Common
5 N.C

The position of the contacts when the coil is de-energized is used to define their state as being either Normally Open (N.O.) or Normally Close(N.C.)

For your fan example lets assume a DC fan and a small buzzer. The fan and buzzer negative wires will get connected to the negative of the DC power supply . The relay will control the switching of the positive voltage to either the fan or the buzzer The positive DC would get connected to the Common. The fan is connected to the normally open and the buzzer is connected to teh normally closed.

With the relay in its normal de-energized state the buzzer will be sounding and the fan will be off. Energize the relay coil and the recontacts will shift position causing the buzzer to silence and the fan to start.


Would this work for my installation?

Thank you for the wire size and breaker info...job in progress as you read this :thumb:

(Now only still need to figure out the fan supply/control and I'm good to get the job done, move the girls in and harvest my Exodus Cheese clones in about 9 weeks...this is my first indoor grow, so quite a learning curve but enjoying it immensely and getting there...my 36 veg'd plants are super-healthy and happy:love:).

If you can source a contactor with an auxiliary switch thats N/C, you would connect the low speed speed wire from the fan to this. Then when the timer energizes the contactor, you would have the hi speed wire connected to that and the aux switch will break. Sounds like you're almost there!
 

TokeMcLeod

New Member
Good stuff booby, I'll go look for a suitable contactor and all should be fine. I tell ya- I was getting worried about this lot.

Many thanks for sharing your knowledge- much appreciated!:bravo:
 
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