supplying sub main from a 3pole mcb?

[Engineer54]

Diversity: The AC I am assuming no diversity as the offices are internal cubicles inside a metal clad building - the condensors are not permitted to be sited outside (landlords restriction) so will be generating heat inside the warehouse and making it even warmer, so the AC will probably spend 3 months on full cooling 12 hours a day.

You're having a laugh here aren't you, never heard anything so ridiculous for a hell of a long time now!! Even if the compressor units were allowed outside these tiny AC units, in what sounds like open cubicles in a large open space building, would be knocking their guts out trying to cool/heat a vast open area. They would have been far better off installing sized AHU's and ducting to cool/heat such areas.... This is a AC installation company, ....Pull the other leg it's got bells on!! lol!!

Why is it we never get the full story in the OP's??

 

[Darkwood]

After an almost sleepless night worrying about it, I will go back to the contractor and highlight concerns (strictly no plagiarism - I will tell them I have consulted the heavyweight sparks!)

I could'nt expect another firm to come in seeing as the money side of things isn't exactly lucrative to say the least - The MD reckons "it'll only take a day mate" ... (Existing DB MCB, connections to & new DB, 6x supply cables, 6 x isolators & Condensor connections, testing etc) so its priced on a wing and a prayer as it is, and technically I only have a days' labour at subbie rate. I'm just glad I went in before to look at it on my own time before I was committed. He also wanted me to take sole charge of the EIC so hence when I saw the design I started to worry ... With the best will in the world I'll think I'll give this one a miss. Once again I am thankful for your frank and very informative opinions, and will tread more cautiously in the future, and within my limits ...

cheers

Well only you know your limits and whether to pass it on, if they expected you to sign for the design of the install too then thats when I personally would have said no, if they want it done their way for whatever reason that's fine as long as they sign for design then they are the ones who will be challenged come any issues in the future that may arise and not you. I've seen plenty of these firms and knowing my stuff I tell them straight my way or not at all - if they want to cut corners my name doesn't go on the design and I am merely the installer.