MK Sentry CU

It depends which one you bought. Some of them have hole knockouts for 20, 25 and 32mm grommets.

For the one that you have, there should be some strips of nylon with castellations with it which you cut and place around the cut out section. You should use them and not allow the cables to come into direct contact with the cutouts.

.andy

To email, substitute .nospam with .gl

My recently installed Crabtree Starbreaker didn't have any grommet strip.

I removed all the 'square' knockouts on the back I'd need, and carefully cut a slightly undersized rectangle in the mounting board. I'd say this is thick enough not to possibly damage the sheaths.

Thanks for responses. Interesting, the first CU I bought from Screwfix had to go back as the main power switch was cracked. Neither it nor the replacement had any of the strips provided. I'll get some bought and fitted.

I've bought a few from there - all have been fine (apart from when they were out of stock for ages), but as you found - none had the grommet strips included.

Alex

In message , Peter Ramm writes

I fitted a GE cU, it had know either for the square cutouts.

TBH, I'm not sure I see the likelihood of the cable being damaged on the plastic edge here as any greater than on a junction box, or plastic mounting box where.

I did think about getting some grommet strip, but I wanted to egt the box fitted, so it'll ahve to be retro-fitted.

I'd tend to agree. Grommets for metal boxes are perhaps a different matter, given the boxes are earthed, and cables might be squeezed into them. This shouldn't happen with a CU.

I was a bit wary when I fitted an mk cu with no grommets - but I did all the cutouts before mounting it on the wall and used a small file to cleanup/smooth all the edges. The cables arent very tight fitting and arent going to move so they should be alright?

To satisfy the requirements for protection against direct contact, any enclosure containing live parts - which obviously includes a CU - must meet IP2x. This means that you must leave no openings through which a

In addition any opening in the top surface of an enclosure, if readily accessible, should meet IP4x. This means having no openings which could pass a 1 mm dia. sphere and effectively forbids taking open T&E cables in through grommets in the top of the unit, if the top is readily accessible. [412-03-02]

Do you really mean 1mm?

Yes - see