3kw heaters installation

[Wardy83]

Hi, I’ve been asked to install 5x 3kw ceiling heaters in a room for a salon.
I just want to check how you would install them?
I’m thinking a radial in 4mm2 cable (singles in conduit), from cu to thermostat, to contactor to heaters, 13amp f/spur at each heater?
Customer wants them all to come on at same time hence the contactor.

Advice/ thoughts Welcomed.

Cheers

Wardy

 

[i=p/u]

Tell me your plan, u have 65A

 

[Wilko]

Hi - I would confirm manufacturer’s fusing requirements.
Just a reminder that no diversity is allowed so 3000/240 = 12.5A times 5 rads gives a load current of 62.5A.

 

[Pete999]

Hi, I’ve been asked to install 5x 3kw ceiling heaters in a room for a salon.
I just want to check how you would install them?
I’m thinking a radial in 4mm2 cable (singles in conduit), from cu to thermostat, to contactor to heaters, 13amp f/spur at each heater?
Customer wants them all to come on at same time hence the contactor.
oughts Welcomed.

Cheers

Wardy

It is recommended that loads of 2KW and above are wired to their own circuit, I would wire 5 Ras/dials 1 for each heater 3 KW is about 13 Amps, 5 3KW is 15000/230 is about 65 A done any cable calcs?

 

[James]

a couple of things worth considering

contactors can be noisy, the clunk of a good sized contactor every few minutes might annoy people if it is located in the wrong place.
if it can’t be located where it can’t be heard, a solid state relay could be used instead (silent in operation )

15kw sounds like a lot for 4mm to carry 65A?
if it is a 3 phase supply that could work but if it is single phase I would think splitting the heaters into 3 separate breakers would help to keep your cable size down.

sizing of the contactor is important, don’t go for one that is close to the current intended.
oversize by at least 50% or it will not last the test of time.

on the control circuit side of things, have you considered the lighting circuit?

if you power the stat and contactor coil from the main lights or a neon switch next to the light switch then it is much less likely to be left on by mistake overnight.
it will of course come on automatically whenever the premises are occupied.

 

[buzzlightyear]

Hay Pete your up early trying to feed the early birds some feed. Lol.

 

[buzzlightyear]

I would put in a 5x radail circuits has the master tells you too.

 

[Pete999]

Hay Pete your up early trying to feed the early birds some feed. Lol.

Nah Buzz couldn't sleep Wife snoring like a Pig

 

[buzzlightyear]

Nah Buzz couldn't sleep Wife snoring like a Pig

Thought about putting a peg on its noise soon wake the bugger up.

 

[Wardy83]

Thanks for the advice and thoughts guys.
I’m thinking to go with 5x radials.
There is a new dB going in at some point soon so capacity is good.
I will look at location of solenoid/ control box as the majority is open plan so noise of a clunk would be an issue.
Cheers
Much appreciated ?

 

[telectrix]

do the heaters have integral thermostats? if so ditch your planned stat. then the contactor only activates when they first switch on in the morning.

 

[Dustydazzler]

Why do they want a kill switch to turn them all on/off at once.
Can't they each just be fed via a switched fused spur with neon indicator so at the start/end of the day someone can simply go round and turn them on/off.

 

[telectrix]

Why do they want a kill switch to turn them all on/off at once.
Can't they each just be fed via a switched fused spur with neon indicator so at the start/end of the day someone can simply go round and turn them on/off.

idleness.

 

[230v50hz]

I've been sent to do a similar task involving 4x heaters on one phase. The MCB is 45A and I've been told to wire it via a contactor and a thermostat. Is it right that I can take the power from the supply side of the contactor, to the stat and then from the stat to energize the coil? I am slightly concerned about taking a much smaller cable to the stat as its on a 45A MCB but the chap I'm working with says its fine as there is practically no load on the stat/coil. Is this correct?

 

[Pete999]

I've been sent to do a similar task involving 4x heaters on one phase. The MCB is 45A and I've been told to wire it via a contactor and a thermostat. Is it right that I can take the power from the supply side of the contactor, to the stat and then from the stat to energize the coil? I am slightly concerned about taking a much smaller cable to the stat as its on a 45A MCB but the chap I'm working with says its fine as there is practically no load on the stat/coil. Is this correct?

Take the control circuit through a slide lock fuse within the contactor housing, been done that way since Jesus played in goal for Bethlehem

 

[230v50hz]

Take the control circuit through a slide lock fuse within the contactor housing, been done that way since Jesus played in goal for Bethlehem

Alternatively, could I just mount an MCB on the DIN rail next to the contactor for the control circuit?

 

[Pete999]

Alternatively, could I just mount an MCB on the DIN rail next to the contactor for the control circuit?

Why not if there is ample space