Air conditioning

[mickeydoolin]

If I'm installing the whole system I will issue an EIC with the Zs taken from the furthest point (usually the indoor unit on a split).

If I'm just providing a supply to an isolator I test up to and including the isolator and just make sure that I state on the EIC what I have done and that the isolator is for air conditioning which is being installed by others at a later date.

I know full well that the AC engineers won't do any form of electrical testing or certification.

I think AC engineers should be allowed to install the interconnecting cables but they should be suitably trained and also provide a minor works for the electrical work that they carry out.

Unfortunately if I'm being honest, most of the wiring that I've seen done by AC engineers has been quite poor. No crimped connections and use on non standard cables (SY cables outside with no UV protection).

Not all are bad though, it all depends on the individual.

How do you record the details on the schedule of test results when two different cable types have been used for the supply to the outdoor unit and then the interconnecting cable?

Also, how do you record the details when the armouring has been used as the CPC for the supply cable and then an internal core/conductor has been used as the CPC for the interconnecting cable?

Doing electrical work for an A/C company who doesn't have a clue is a nightmare!!!

They want the interconnecting cable treated as a separate circuit which is surely incorrect. The whole system is protected by the same MCB so therefore in my opinion it is one circuit???

 

[Pete999]

How do you record the details on the schedule of test results when two different cable types have been used for the supply to the outdoor unit and then the interconnecting cable?

Also, how do you record the details when the armouring has been used as the CPC for the supply cable and then an internal core/conductor has been used as the CPC for the interconnecting cable?

Doing electrical work for an A/C company who doesn't have a clue is a nightmare!!!

They want the interconnecting cable treated as a separate circuit which is surely incorrect. The whole system is protected by the same MCB so therefore in my opinion it is one circuit???

Just test and report on what you are responsible for, if others are completing the rest then that's up to them, treating the inter connecting wiring as a separate circuit is nothing bit BS and prevarication, probably because they have no clue on how to test and certify or don't have the correct test equipment . Do your bit get paid issue the EIC job done, Bin there got the T shirt many times over.

 

[Lucien Nunes]

This is an interesting question (I know it's an old thread.) The main issue here is whether the interconnecting cable is part of the electrical installation or part of the air conditioning equipment, not who is capable or competent to do what. Most of the units I've seen have at least a switched line controlled by a relay on the PCB, and as such form part of the control system of the A/C rather than just another power feed to a second location. May I offer a couple of similar situations to consider:

1. Industrial machine tool. Supply SWA runs down the wall, through an isolator and into the machine panel. Another SWA runs out from a contactor in the panel, along the wall to a hydraulic power pack that is part of the machine but separately mounted. Four SY cables run along the same tray connecting the machine's PLC to the pressure switches and solenoids on the hydraulic pack. Are any of these cables part of the building's electrical installation?

2. 16A socket on the wall feeds AV system rack. Inside the rack is a power distribution unit with 10 sockets each switched by a relay controlled over ethernet by the AV system processor. A plug in one socket feeds a relay box for the motorised projection screen, controlled by RS232 from the serial port. Out of this relay a 4-core H07 cable runs up trunking into the ceiling, taking switched 230V to the reversible screen motor. Is that cable part of the building's electrical installation or part of the AV electronic equipment?

 

[James]

@Lucien Nunes raises an interesting point.

Many production lines are more than just an item plugged in.

Often a large supply feeds an isolator, from there it supplies a large control panel.
More often than not, the protective device for the main supply is far too big to provide fault protection for most of the equipment on the production line.
Main control panel will often have rows of circuit breakers, connected to bus bars for separating the supply into multiple smaller circuits.
This arrangement could be compared to any other distribution board in terms of the protection it provides to all the circuits that it feeds.

Do we consider this to be a distribution board in terms of the fixed wiring?
In general no, we don’t for the following reasons.

The production line is likely to have many hazards that are well above anything described in the electrical regs, each of these will have been addressed during the design, construction and commissioning of the line.

The simple approach that is generally used for dealing with faults detected by distribution boards etc is as follows. detect fault, turn off power to affected circuit as quickly as possible and always within x seconds. As a general rule this provides the highest degree of safety that can reasonably be expected.

For many production processes, the above approach can actually increase the risk by bring in extra hazards, some could be far worse than the original fault.

Work holding devices, electromagnetic clamping and lifting etc are some that spring to mind.
Others may be less obvious. cooling pumps, local ventilation, vacuum pumps etc.

For a production line, these modes of failure should have been risk assessed both individually and as part of the whole process.
Overload protection may be bypassed automatically or manually on some circuits to provide time for a backup system to start or another process to be stopped safely.

So in some ways a machine control panel is a distribution board
But they should not be considered as such from an inspection and testing point of view, specific knowledge and understanding is required before some recently qualified “inspector” sucks their teeth and says
Oh that’s dangerous, there should be and rcd on that.

In some places, by “improving the safety” you could be unwittingly signing off someone’s cause of death.

 

[Petej999]

As many sparks do we install supplies to air con units which we test, certify and move on.
We never get involved in an6 of the interconnection wiring as the AC companies do this themselves but my question is, should they be issuing certification for this, possibly a minor works as they are altering a circuit

When ever I installed A/C units I did it in conjuction with the A/C installers, so the interconnection was completed at the same time, most of the time I actually did the whole install pipework and all, so an EIC was issued by me.