VRV install

[declan simmonds]

Hello to all at R.E
I have a few questions about installation in different countries. First of all i would like to explain the system I am currently working in madrid on a big install,
There are 7 buildings each have 4 floors, each floor has 8 daikin fan coils which runs of one condenser unit. I have noticed that none of fan coils or the B.S boxes have any fuseable isolators, the electrics are all connected to a ring on a R.C.D, the B.S boxes are on a seperate ring also.
Personally i think this is rather dangerous but i suppose in spain there not as tight with the electrical regs, also it would be a nightmare for servicing. Are there any spainish A/C engineers that would like to explain to me whats going on ?or is this normal pratice.
Cheers declan

[nike123]

Regardless of type of equipment or country, every power supplying cable should be protected in case of short circuit by matching circuit breaker. If you have cable with cross section of 2,5mm^2 then it must be protected with, say, 20A or less circuit breaker .If all equipment on that circuit doesn't draw more than that current, everything is OK.

[Thermatech]

This is a question which needs to be addressed by the members here who are 17th edition qualified.

Is it a UK legal requirment that all indoor fan coil units must have a fused spur switch for 240v electrical isolation ?

We all take it for granted that every indoor unit must have a local isolator but is it actually part of the regs that this is an absolute legal requirment ?

[The Viking]

This is a question which needs to be addressed by the members here who are 17th edition qualified.

Is it a UK legal requirment that all indoor fan coil units must have a fused spur switch for 240v electrical isolation ?

We all take it for granted that every indoor unit must have a local isolator but is it actually part of the regs that this is an absolute legal requirment ?

Sorry, haven't got the 17th yet, but doubt this would have changed.

BS7671:2001:
131-14-02
Every fixed electric motor shall be provided with an efficient means of switching off [all voltage],readily accessible, easily operated and so placed as to prevent danger.

(it is generally accepted that readily accessible means "within arms reach")

[Thermatech]

So in the UK most electical contractors interpret this to mean a fused switched spur mounted at arms length from each indoor unit. ?

This seems to be the standard which we are used to on most commercial projects for many many years now.

But could some also interpret that the mcb in the distribution board is
1/ an efective mean of switching off
2/ readily accessible.
3/ easily operated.
4/ placed as to prevent danger.

There will always be those who are always looking to cut costs & might read into this that a local fused switch spur is not needed to comply with the regs.

[The Viking]

Provided that you can reach the distribution board from the A/C unit, utilising the MCB for both purposes would [technically] be OK.

(But there might be issues when it comes to inspection and testing, depending on the sparkie that carries it out)

Fused (but un-switched) spurs are a grey zone. Often used to prevent end-users to use the spur as an on/off switch but not easy to use in an emergency....

[airefresco]

Declan that sounds perfectly normal for Spain (well the Canary Islands, atleast). However, I would image indoors to be on different breakers than the BS boxes and Outdoor units. I don´t think I´ve ever seen an isolator or fused spur over here.

Normally, the units are wired directly to dis board.

[frank]

The reason they fit fused switch spurs on to the indoor unit is that the MCB will be rated for the ring main size, not the local load.

By using a fused spur you are applying discrimination and protecting the equipment

[declan simmonds]

Hello all thanks for all the replies to my question i agree with frank the fused spur is used to protect the equipment at the local load.
In spain the rules and regs are different thats if there are any . The bs boxes and the fan coil are on seperate breakers ,
but there obviously rated for the total load rather than one unit which i think is crazy Also the one to one splits dont have indoor isolators or outdoor islolators either there wired direct to the diszy board i suppose i just have to accept that electrical regs are slack
Its about time spain got with the programe well thats what i think
cheers declan

[nike123]

Hello all thanks for all the replies to my question i agree with frank the fused spur is used to protect the equipment at the local load.
In spain the rules and regs are different thats if there are any . The bs boxes and the fan coil are on seperate breakers ,
but there obviously rated for the total load rather than one unit which i think is crazy Also the one to one splits dont have indoor isolators or outdoor islolators either there wired direct to the diszy board i suppose i just have to accept that electrical regs are slack
Its about time spain got with the programe well thats what i think
cheers declan

It is common misconception that circuit breakers in home installations serve as appliance protection. In fact, they are there to protect cables and installations and should be sized according to type of load (slow, normal, fast breakers) and size of feeding cable.
If equipment need protection, then fuses (and other safety devices) in equipment are carefully selected and correctly sized for that purpose in time of production of equipment, and it is not on equipment installer party to fiddle with that.

[IceMan08]

we installed a huge daikin plant at the mayfair, ALL VRV,s had their own breaker on the dist board as well as having an isolator tucked inside the access panel. All A/c units had a fused switch that went to a seperate breaker,as did the bs boxes,
my mum lives in spain and her house wiring would probably be classified as dangerous in the uk! Just goes to show we have higher (safety) standards!!
By the sound of it, if anything shorts then you,ll have a lot longer job looking for the fault, and if theyre not rated high enough then your summers going to be fun huh?!?!

[Refrigerologist]

Circuit breakers should not be used as a means of isolation! Therefore each fan coil should be provided with a local point of isolation, unless a lockable isolator is installed into the ringmain. This would require a 4pole isolator to maintain the ring correctly. I have never seen that done. We always install switched, fused spur outlets as it make servicing easier. The only problem then is when the end user switches off a fan coil at the spur, this causes a U4 or U9 error.

[airefresco]

There are some shocking electrical installs here. However, the spanish regs have got much tighter over the last fews years. TBH the worse electrical jobs I have seen over here have all been done by the english. (except for my apartment that was wired about 10 years by a spannish "electrican". It had a peice of 1.5mm single strand cable that came into the apartment from a breaker in the house below. That cable was then twisted (no even taped) to three other cables that served the lights and sockets. The water heater was wired into the bathroom light switch. It amazes me that the place didn´t burn down running 10 years like that.)

Like Nike said the breakers are there for the cable, not for the equipment, so it makes perfect sense not to bother with isolators. They don´t really serve any purpose. If you need to work on a system, then you can switch the breaker off. If the unit develops a fault then it will either, trip the breaker or blow the fuse on one the PCB´s.

[nike123]

(except for my apartment that was wired about 10 years by a spannish "electrican". It had a peice of 1.5mm single strand cable that came into the apartment from a breaker in the house below. That cable was then twisted (no even taped) to three other cables that served the lights and sockets. The water heater was wired into the bathroom light switch. It amazes me that the place didn´t burn down running 10 years like that.)

You see now, that that man has known his job.

[airefresco]

Just want to clarify. The wiring in my apartment was like that for 10 prior to me moving in. It's all good now.