Location of bell transformer in CU

[SW1970]

Hi folks, replacement high integrity CU going in. Existing CU has bell transformer and customer wants bell transformer in new CU as well. Question is, what is best position in CU? Dont want to eat up the high integrity positions, so ok to provision in an RCD protected position? I know it's not necessary because of SELV but is this approach recommended?Many thanks, SW

 

[malcolmsanford]

Put it in with the downstairs lighting circuit.

The RCD is really protecting the 230volt side of things to be honest. If for instance you buried the 230volt cable and it might need protection under reg 522.6.6.

 

[Adam W]

I reckon you could put it anywhere really - no need to rcd protect it but that wouldn't hurt.
Probably best to put it furthest away from the main switch so it's out of the way, and likely to draw the lowest current.

 

[ian.settle1]

Put it in with the downstairs lighting circuit.

The RCD is really protecting the 230volt side of things to be honest. If for instance you buried the 230volt cable and it might need protection under reg 522.6.6.

How can he bury the cable within the CU?:book:

 

[Knobhead]

I honestly can’t see the point in putting a bell transformer in such an expensive housing. It introduces unwanted heat and takes up useful space. Stick it in a cheap box somewhere.

 

[SW1970]

Yes good idea. Thanks.

 

[MarkieSparkie]

I reckon you could put it anywhere really - no need to rcd protect it but that wouldn't hurt.
Probably best to put it furthest away from the main switch so it's out of the way, and likely to draw the lowest current.

As Novus says, furthest away from main switch at the end of the DIN rail, because a bell transformer is at it's least efficient most of the time and usually have high copper losses in order keep the physical size small. By putting it in this position it has free air on at least three sides to aid heat dissipation. I usually adopt Tony's method and fix a independent transformer external to the DB, so that valuable DB ways are not wasted and allowing additional circuits to be easily added at a later date.
Note:- several manufactures make single module bell transformers.

 

[malcolmsanford]

How can he bury the cable within the CU?:book:

It was a for instance mate in order to give an example for the OP when he commented on SELV not requiring RCD protection. The 230v cable may need RCD protection if it was buried and did not conform to Reg 526.6.6.