32amp radial

[dokkan1080]

In a school today helping an approved contractor.

There is a over door fan heater on a 32amp radial fed off a rotary isolator.

It then goes into a bank of 3 switches that are used to control it.

The swtchs are double pole rated at 20 amps.

Isn't that a danger being on a 32 amp 4mm mcb

 

[buzzlightyear]

No , not over rated 4mm on a 32 amp
Plus the rating of the heater .

 

[static zap]

bank of 3 switches that are used to control it.

are these On/off FAN and power settings ?
(may share the current)

 

[dokkan1080]

are these On/off FAN and power settings ?
(may share the current)

Yes ones to turn it off and on, the other two are power settings

 

[Wilko]

Hi - what is the kW rating of the heater?

 

[Julie.]

If the heater is over 20A then the switch would be overloaded (even if elements are split) as one is used to switch to whole load.

As it's a fixed load, the cable and switches only need to be rated for the load - not the protective device, so it all depends on the size of the load.

 

[davesparks]

Are you sure it's a 20A switch in the drid and not a 32A?

 

[dokkan1080]

Are you sure it's a 20A switch in the drid and not a 32A?

If the heater is over 20A then the switch would be overloaded (even if elements are split) as one is used to switch to whole load.

As it's a fixed load, the cable and switches only need to be rated for the load - not the protective device, so it all depends on the size of the load.

Didnt think you could get a 32amp grid switch...

 

[Sintra]

You may find that the switches only switch relays or contractors within the heater so no load as such.