CU sideways ?

[ac1951]

Anybody know whether or not it's ok to mount a CU sideways ? Are there any known issues with trips (MCB's , ELCB's etc) not functioning correctly.

thanks Andy

[dennis]

DIN rail ones are routinely mounted both ways depending on the chassis they are fitted to.

[ARWadworth]

No problems at all. Remember that on 3 phase boards the MCBs/ RCBOs are usually in the horizontal plane.

Adam

[js.b1]

If you have not already found out...

Legally. Can find no limitation in BS7671 regarding CCU sideways.

Manufacture technical. MK say ok even if fully populated by RCBO RCD (or MCB), but did indicate it might be a problem if several 50A RCBO from thermal issues. Mem & hager say the same. All the above say it is commonly done where no alternative, I investigated in 2001 & checked again in 2004.

Inspection. Compliance with bs7671 overrules "self-certifying body best practice", just note as a deviation if ever challenged by a jobsworth. However see below for practical limitations re busbar shield

Practical. Inconvenience - 1 module width CPD will rotate/tilt downards under gravity in a sideways CCU, making refitting the cover & cover-with- blanks very difficult in anything with more than 12-ways. I know MK 16- ways is a dog and 20-ways would be unusable for tilt. Use of solid 1 module blanks fitted to the DIN rail might prevent tilt sufficient to make it workable in place of clip-into-front-cover-blanks. Serious - Busbar cover may not be retained and fall off making live tests unsafe, MK for one do an insulated busbar however I have never seen it. MKs busbar shield is a pos even if you fit the CCU horizontally if the wall has even the slightest tilt outwards, falls out too easily.

IP rating. Top/Front of any wiring accessory/CCU must meet IP4x - prevent penetration by 1.0mm ball bearing. Sides of any wiring accessory/CCU must meet IP2x - prevent penetration by 12.5mm ball bearing. Realise use of MKs top cable k/o will not meet IP4x unless you use Hagers CCU stick-in foam tape or silicone everywhere, so ironically turning the CCU sideways now provides lots of side cable k/o that are only subject to IP2x.

The real solution to MKs (bad) CCU design is to use the back-outlets, stick the CCU on a wooden board & pass cables thro from the rear. You do not need to fit cables in trunking to the CCU if in a cupboard (ie, mechanical protection), but you do need to clip the cable so movement of the cable does not move the end terminations inside the CCU. Cable clips or P-clips would be ok. Note Fischer do a nice range of cable clips including some that will accommodate multiple cables clipped under a bar. If using P-clips on flat cable ensure you do not trap the sheath, can be preferable to use screws rather than bashing away with nail clips and hammering the sheath.

Cant think of anything else... make sure your MEB is sized ok.