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Topic Title: Really Daft Question.... Yes really
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Created On: 25 February 2014 10:31 AM
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 25 February 2014 10:31 AM
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antdon

Posts: 68
Joined: 07 November 2007

Ok
why cant I connect a single phase load to a 3ph mcb??
Are the characteristics really that different?
 25 February 2014 10:48 AM
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MrP

Posts: 843
Joined: 24 March 2006

A triple pole 60898 MCB comprises of 3 single pole 60898 MCBS strapped together therefore yes you can use a single pole of three and why not

Good luck buddy

MrP day 7
 25 February 2014 10:58 AM
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broadgage

Posts: 1308
Joined: 07 August 2007

Yes you can. (presuming that a neutral is available in the DB)

As above, most 3 phase MCBs are in fact 3 single phase units attached together.

Also consider that some 3 phase loads may under some circumstances only load 1 phase, and no one worries about that.

As an example I have a 3 phase portable fan heater of 18KW output and fitted with a 32 amp 3 phase and neutral plug.
This appliance has 3 heat settings, and if used on the lowest setting is in effect a single phase 6KW heater.
Used thus it would still be properly protected by a 32 amp 3 phase MCB in the DB.
 25 February 2014 11:06 AM
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rogersmith7671

Posts: 886
Joined: 04 November 2004

Ok
why cant I connect a single phase load to a 3ph mcb??
You can.

Are the characteristics really that different?
The characteristics of each mcb have been designed to meet the requirements of the circuit designer, so there will be differences
But a type b mcb is a type b mcb, it's just three clipped togther.

Regards
 25 February 2014 12:19 PM
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AdrianWint

Posts: 262
Joined: 25 May 2006

Yes can connect a single phase load to a three phase MCB.

However, you shouldn't connect three separate single phase loads to a three phase MCB.....

A three phase overload module would however be a different matter.......
 25 February 2014 01:31 PM
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MrP

Posts: 843
Joined: 24 March 2006

Originally posted by: AdrianWint





However, you shouldn't connect three separate single phase loads to a three phase MCB.....


Where does it say you can't ?

MrPstill day 7
 25 February 2014 04:25 PM
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antdon

Posts: 68
Joined: 07 November 2007

Many thanks for all the replies.....
 25 February 2014 04:49 PM
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Jaymack

Posts: 4664
Joined: 07 April 2004

Originally posted by: MrP
Originally posted by: AdrianWint
However, you shouldn't connect three separate single phase loads to a three phase MCB.....

Where does it say you can't ?


The regulations call for a means of isolation. They also call for minimum disruption, this wouldn't comply.

Regards
 25 February 2014 04:56 PM
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AJJewsbury

Posts: 11547
Joined: 13 August 2003

The regulations call for a means of isolation. They also call for minimum disruption, this wouldn't comply.

A bit like feeding half a house worth of MCBs from the same RCCB you mean?
- Andy.
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