air gap bettwen mcb

[midgetman]

Reading the manufacture instructions for this inline electric central heating heater - it states "a blank must be fitted between each MCB in the consumer unit to provide ventilation" ?!?!?!

It then says On completion of the work the installation must be tested to IEE Regulations and an NICEIC Inspection and
Completion Certificate must be issued.
I must follow manufacture instructions - I'm with a different scheme I cant comply lol

 

[telectrix]

report them to your scheme provider. what a load of bollox.

 

[Pete999]

A complete load of bollox as Tel says

 

[Octopus]

Which MCB manufacturer is it then...... name and shame!

 

[Pete999]

Not Proteus by any chance, now there's a carp piece of carp if ever I saw it IMHO

 

[R G]

Its not referring to contactors by any chance is it , these are the only things that need ventilation on a din rail,..

 

[Knobhead]

Considering he’s quoting the boiler manufacturers instruction I think the make of MCB is irrelevant.

 

[HandySparks]

Here we are, chaps.

It's a common requirement for circuits loaded to maximum for long periods. Straight out of the Crabtree Circuit Protection Technical Data:

AMBIENT TEMPERATURE CONSIDERATIONS l
Starbreaker and Loadstar MCBs are calibrated to meet the requirements of
BS EN 60898, 30°C Reference Calibration Temperature. At other temperatures
the following rating factors should be used:
At 40°C 0.9 At 20°C 1.0 At 0°C 1.1

Adjacent thermal-magnetic MCBs should not be continuously loaded at or
approaching their nominal rated currents when mounted in enclosures. It is
good engineering practice to apply generous de-rating factors or make
provision for adequate free air between devices. In these situations, and in
common with other manufacturers, we recommend a 70% diversity factor is
applied to the MCB nominal rated current where it is intended to load the
MCBs continuously (in excess of 1 hour).

 

[R G]

It would be nice to hear back from the guy ,,,,

 

[midgetman]

Amptec heatrae sadia

 

[londonlec]

I've read that before in an Amptec manual for their 6kW electric boilers.

 

[R G]

Hmmm , thats interesting , I suppose with Electric Heating in use and no diversity , It would be wise to stick to the 70% diversity factor for the MCB when designing the circuit , very interesting ,,

Amptec Electric boilers go from 6kw up to 12kw I think , Maybe wise to put these on there own board , as usually on off peak tariff ,,

 

[Silly Sausage]

6kW on a 32A MCB would be ~ 81%.
Would the above unit be running continuously >1 hour?

edit: The 6kW was the 1st one I looked at.

 

[R G]

I should imagine with a 6Kw unit , A 40 Amp MCB and a 6mm circuit would be what you would need , I think these are on for quite a time to heat all the water in a conventional heating system ,

 

[Engineer54]

Here we are, chaps.

It's a common requirement for circuits loaded to maximum for long periods. Straight out of the Crabtree Circuit Protection Technical Data:

AMBIENT TEMPERATURE CONSIDERATIONS l
Starbreaker and Loadstar MCBs are calibrated to meet the requirements of
BS EN 60898, 30°C Reference Calibration Temperature. At other temperatures
the following rating factors should be used:
At 40°C 0.9 At 20°C 1.0 At 0°C 1.1

Adjacent thermal-magnetic MCBs should not be continuously loaded at or
approaching their nominal rated currents when mounted in enclosures. It is
good engineering practice to apply generous de-rating factors or make
provision for adequate free air between devices. In these situations, and in
common with other manufacturers, we recommend a 70% diversity factor is
applied to the MCB nominal rated current where it is intended to load the
MCBs continuously (in excess of 1 hour).

Reading this, we have to now ask when is the rating of a MCB not the rating?? Since when has MCB ratings been subject to continuous loading in excess of one hour??

Now Who designs these CU's and DB's that these MCB's will be mounted in?? If it is, as they say ...''good engineering practice'' to apply generous de-rating factors (70%!!!!!) or make provision for adequate free air circulation, why have they not incorporated these provisions into the designs of both the MCB and CU/DB MCB fitting/mounting configurations...