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Its not just for economy its for space as well theres not much in the units or in the fancy pants curvy trunking either. :)

With the reduced current at the relevant points the Volt Drop decreases even with the increased length hence the reduced cable CSA at those points only (me thinks)

How dare you that took me a whole 5 mins on power point !!!

Still doing this AC job: There are 3 internal Fan/Evaporator units daisy chained together at Varaious locations in the office space. As the units are daisy chained Im pretty sure the load will be spread. I.e. the total 21A load will not be present at each fan unit as its daisy chained, Right...

Well I know where I would start looking then. Specially if the plumber has added a spurr off your ring to supply a boiler or whatever. Switch the MCB off before you start though :wink:

The first question to ask is did it trip prior to the plumbing

Thanks for all the comments on this one. FYI its a Mitsubishi unit.

Yes its a steel frame building, Dont know Im over ther in a bit I will take a look and I may take some pics, I know how you love pics. Could open a can of worms this one if every AC units pipes have to be main bonded. I would bet the vast majority installed are not.

So you would recommend running a seperate Earth to bond the pipes where they enter the building?

The building is a largish warehouse with a few offices built inside. Its brand new and is metal clad inside and out with about 10" of insulation in-between, not a brick in sight (cheap). The compressor stands on a concrete pad outside in a cage. The supply cable comes from the plant room about...

The things you learn on this site :wink: Cheers 123. Bet this is the same in the Red book, havnt got mine yet. Anway assuming the earth or SWA equivalent agrees with table 54H do you agree with my scenario regarding satisfying the bonding of the AC pipes via the supply cable earth?

You talking about the incoming supply to the DB? if so I cant remember Im in the office but I guess your going to tell me that the MEB has to comply with table 54 H for PME i.e. 35mm or less then your MEB has to be 10mm . Between 35 and 50 it has to be 16mm and so on. Right?

The thing is the Pipes fitted to the the compressor are bonded to the Earthing teminal in the compressor, I have done a continuity test. So in effect the supply cables earth when connected to the earthing terminal of the compressor is bonded to the pipes. So as long as the earth cable in the...

I dont have a problem bonding the pipes but the compressor is 40m from the DB. Cant I just bond the pipes to the earth in the supply cable, or would you recommend using a seperate earth from the MET to bond the pipes. Supply cable is 6mm as is the Earth. Its also SWA so surely the SWA is large...

Do you have to provide a Main Equipotential Bonding conductor to Earth Air conditioning pipework? 413-02-02 (iv) (Brown Book) says so. I would have thought the Earth in the Supply Cable is adequate as the Pipes in AC systems are linked to the earth in the outside units Circuit board...

Thanks Thripster thats a help

When a motor starts your going to get high in-rush currents which exceed the normal operating current for a short time. To cope with that you would use a C or D type MCB, fine with that Questions: If say the operating current of a motor is 20A what do you expect the in-rush current to be 20%...

Thanks chaps, found a complete replacement hob on currys partmaster, still a rip off but the wife is doing my head in now so Im going to have to cough up

Over the Christmas period a heavy pan fell out of the cupboard above our ceramic hob shattering the glass. A new piece of class costs almost as much as a complete replacement hob (acording the the manufacturers spare parts dept) so Im a bit loathed to pay for it. Can anyone tell me if you can...

Thanks Gents Didnt know that about B&D taking over Dewalt. Might get a Makita after all. My use is professonal, My firm installs aircon in commercial building and occasionally in homes. We normally use corded drills for big holes (corebits etc) but increasingly I like the use of a a...