[Question] New inverter aircon installed and ELCB bypassed

[Viksharma]

Hi guys

I have a query. I got a new inverter aircon installed today (18000 btu). So in accordance with law an isolator was installed (30a) from a new mcb (30amp) on the DB Board. So when we switched the aircon on earth leakage tripped - it happened every time the breaker of aircon was turned on.
The installer then said we need to bypass the earth leakage for aircons esp the inverter aircons. So he bypassed the earth leakage to connect the aircon.
Is that right - aircons should not be on earth leakage and should be bypassed or is there an installation problem here
Thanks
Vik

[ians]

A weatherproof 30 amp isolator outside next to the aircon is correct.

A 30 amp mcb ... means it has a 4 mmx 2core wire feeding the isolator ? I would normally suggest a D curve type breaker is used with 2.5 mm wire ... however I have found the Dcurve type breakers make a buzzing sound when inverter aircons are connected ... In theory a d curve type breaker shouldnt be required because the new inverter type aircons dont have the inrush like the older units.

With regards to the earth leakage tripping when connected to inverter units ... I dont have enough inverter aircon experience to comment (or should I say havent had this problem) ... however what I can tell you ... so long as a COC was issued for the isolator installation and all the tests carried out where within spec ... insulation restance was above 1 Meg ... there is no problem with the isolator not being connected to earth leakage (unless something has changed since I last read the SANS regs)

A partial COC is required to add to the exisiting COC ... IF you dont have a COC for the property ... I strongly suggest you get one ASAP ... the reason I susggest it ... if you cant produce an exisitng COC for your property ... you cant really expect anyone working on your property to produce a partial one without charging you for a full inspection report and test.

[GCE]

Hi

Aircon circuits do not have to be on ELU
I have not put inverter types onto ELU so not sure if that is a problem but generally ELU and electronics don't like each other so it would make sense that it could be a problem

Have pasted the reg below that deals with what needs to be on ELU


6.7.5 Earth leakage protection
6.7.5.1 Except as allowed in 6.7.5.5 and 7.10.1.6, non-auto-reclosing earth
leakage protection shall be provided
a) in a new installation for circuits that supply SANS 164-1 or SANS 164-2
type socket-outlets,
b) in an existing installation for all the circuits that supply socket-outlets when
any such circuit or circuits are rewired or extended.
NOTE It is recommended that earth leakage protection be installed in all circuits
that supply socket-outlets in legacy installation.
c) in a.c. circuits supplying water heaters.
6.7.5.2 Industrial type single-phase and three-phase socket-outlets
(including “welding” socket-outlets) shall comply with the requirements of
SANS 60309-1 and SANS 60309-2 and, except as allowed in 6.7.5.5 and
7.10.1.6, shall have earth leakage protection if the circuit is intended to supply
portable or stationary class I appliances

[Justloadit]

Interesting phenomena with respect to Inverters.
They have huge capacitors which are fed from the mains as a reservoir to run the motor from.
They should have a PTC device in series with the mains, to reduce the inrush current when power is applied while they charge up, especially if they have been off the power for long periods of time.
If this PTC device is not part of the circuit, then the high inrush current causes eddy currents to flow into earth/chassis, and the ELU picks this up as a ground fault and trips.

To reduce this, careful design and assembly is required, to reduce the possibility of these eddy currents, which is probably dismissed during high volume manufacturing.

So the only solution, is to eliminate the ELU and have a standard suitably rated breaker.

[AndyD]

There's also an 'S' type earth leakage that incorporates a time delay. I think the delay can vary between manufacturers but the last time I tested one it was about 300mS.