3 x 1.5kw heaters on one circuit

[Mabro22]

Hi,

been asked to wire 3 x 1.5kw heaters in offices in an old warehouse.

2.5mm radial - 20amp rcbo with 20amp DP switch with flex outlets

That sound about right?

 

[Pete999]

Hi,

been asked to wire 3 x 1.5kw heaters in offices in an old warehouse.

2.5mm radial - 20amp rcbo with 20amp DP switch with flex outlets

That sound about right?

Bit near the limit if they all come on at once

 

[GBDamo]

Sounds near the knuckle, whats the history?

Any history of tripping, visual signs of cable damage.

 

[Pete999]

Bit near the limit if they all come on at once on 2nd thoughts 4.5kw @ 230v is 30 AMPS about, 3 separate circuits would be my choice.

 

[Mabro22]

Sounds near the knuckle, whats the history?

Any history of tripping, visual signs of cable damage.

The old heater that’s in just now is a 3kw on a 16amp breaker but has gave up and they want it replaced - but have also asked for another 2 added to this. There’s only 1 way left on the distribution board that’s the problem I have

 

[Pete999]

The old heater that’s in just now is a 3kw on a 16amp breaker but has gave up and they want it replaced - but have also asked for another 2 added to this. There’s only 1 way left on the distribution board that’s the problem I have

Put a larger CU in

 

[westward10]

Put a ring final circuit in. Does it actually need rcd protection.

 

[GBDamo]

Sounds near the knuckle, whats the history?

Any history of tripping, visual signs of cable damage.

Re

The old heater that’s in just now is a 3kw on a 16amp breaker but has gave up and they want it replaced - but have also asked for another 2 added to this. There’s only 1 way left on the distribution board that’s the problem I have

Ah, new heaters on old existing circuit.

Installation method? It'd take a lot to derate 2.5 down to less that 20A mind.

19.6A load, then cycling would most likely be fine.

Any chance of throwing a return leg in and making it a ring?

 

[Dave OCD]

Or you could run a 4mm radial and have individual switched/fused spurs at each heater, you could use deeper back boxes to make it easier.

 

[Mabro22]

Re
Ah, new heaters on old existing circuit.

Installation method? It'd take a lot to derate 2.5 down to less that 20A mind.

19.6A load, then cycling would most likely be fine.

Any chance of throwing a return leg in and making it a ring?

Would be very awkward but could make it a ring, the cable is run above ceiling tiles but runs through insulation which is a problem

 

[Dave OCD]

Pete it's a fraction under 20 amps, not 30.

 

[GBDamo]

You could demolish the warehouse and relocate the business to warmer climes and have no need for the heater.

There's a lot you could do but I expect, like me, you have a customer on a budget and are trying to give them something that will work, is safe and is compliant.

What you are suggesting appears to fit those criteria.

 

[westward10]

Would be very awkward but could make it a ring, the cable is run above ceiling tiles but runs through insulation which is a problem

Some things are not as difficult as you think they are going to be.

 

[Pete999]

What Voltage are you using?

 

[GBDamo]

Would be very awkward but could make it a ring, the cable is run above ceiling tiles but runs through insulation which is a problem

If that's the case then a thorough assessment of the installation method is needed to ascertain the derating required.

A return leg may be the best route, gives more wiggle room and peace of mind.

 

[Pete999]

So it is my bad math was never my strong subject lol

 

[Pete999]

What Voltage are you using?

Ignore the question my bad

 

[Mabro22]

You could demolish the warehouse and relocate the business to warmer climes and have no need for the heater.

There's a lot you could do but I expect, like me, you have a customer on a budget and are trying to give them something that will work, is safe and is compliant.

What you are suggesting appears to fit those criteria.

That’s what I was thinking
But I think I’ll just go for 4mm radial with 13amp switched fused Spurs at each heater

 

[Dave OCD]

No worries Pete. We all make a mistake now and then.

 

[Dave OCD]

That’s what I was thinking
But I think I’ll just go for 4mm radial with 13amp switched fused Spurs at each heater

The invoice for the design consultation will follow shortly.