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Old 4th July 2020, 23:43   #6646
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Default Re: The home / office air-conditioner thread

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Originally Posted by anupmathur View Post
You should check whether the correct type of MCB is being used. You need a Type 'C' MCB (rated for inductive loads, i.e. loads that cause a large start up surge).
Thank you. How do I find out? The pictures of the MCBs are attached. Their labels say B20 and B25. Should they read C20 and C25 perhaps? First photo is of the main switchboard, second one the Ac switchboard.
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Old 4th July 2020, 23:51   #6647
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Default Re: The home / office air-conditioner thread

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I am also in the market for a 1.5T window AC. This will be my main high usage AC and the room is such that I cannot install a split unit, so window it has to be.
Also evaluating this unique model from LG.
https://www.lg.com/in/window-ac/lg-JW-Q18WUZA
https://www.amazon.in/dp/B07KRBW7X8/..._3BzMEb879W4TC
Bought this AC day before yesterday - 5 star, 1.5 T

Price = 32,000 (Plus 5% cashback on my ICICI credit card)
Extended warranty = Re 3,231 (two years, so total warranty = 3 years)
Removal of old AC + Installation = 750
Retailer = Vijay Sales, Dwarka.

I was offered Rs 3,000 for my old 1.5 T window AC, which I refused. Got that one serviced, cleaned, and the gas refilled. It will now do duties in a room that is seldom used.
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Old 5th July 2020, 07:03   #6648
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Default Re: The home / office air-conditioner thread

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Originally Posted by Gansan View Post
Thank you. How do I find out? The pictures of the MCBs are attached. Their labels say B20 and B25. Should they read C20 and C25 perhaps? .....
Indeed, they should be marked C20 or C25. The ones currently fitted are type B.
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Old 5th July 2020, 10:32   #6649
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Default Re: The home / office air-conditioner thread

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Originally Posted by neeraj0272 View Post
Any expert in electric supply, please care to explain me the below point:
All of my air conditioners are leaking some amount of electricity.
As Aroy Sir mentioned prepare a good earth. But don't connect to the earth directly at the first instance. If there is a short to the supply in your ac, it would result in a fire incident. Most fires in house/industries are caused by short circuits - some owing to the excessive heating of the conductor due to overload and eventually resulting in burning of the insulation. So use a 60 W incandescent bulb in series with the proper earth and your appliance earth (green wire) first. If the bulb lights up with full intensity, you have a short between the live/phase and the appliance ground.
Solve that first before connecting the true earth. It might sound a bit confusing at first - appliance ground and true ground. In a server room I had set up, one of the UPS developed a partial short and on a fateful night it ended up in a fire. Fortunately an electronics fire alert triggered us to act just in time. Contrary to conventional wisdom, we permanently removed the true ground for all other UPS to prevent further incidents.
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Old 5th July 2020, 12:30   #6650
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Default Re: The home / office air-conditioner thread

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Bought this AC day before yesterday - 5 star, 1.5 T
The only option at the moment in the 1.5T inverter window type category seem to be LG and Voltas. We got two Voltas inverter units last year. Seem to be doing fine. Replacing another one shortly. I am thinking to not go in for the Voltas again. I have my eyes on this LG unit. Mainly for the retro looks and the advertised quiet sound rating. The extra tech features are an added bonus. What are your early impressions in terms of noise levels and your reviews on the app functions?


Thanks in advance!
Promit
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Old 5th July 2020, 15:34   #6651
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Default Re: The home / office air-conditioner thread

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Originally Posted by anupmathur View Post
Indeed, they should be marked C20 or C25. The ones currently fitted are type B.
Thank you. In what way is a C type MCB different than installing a higher capacity B type MCB? Also, can high inrush current cause any problem to the Stabilizer or Ac over a period of time? This particular stabilizer does not have much of a delayed start. Once switched on, the timer runs from 5 to 0 and then it takes just another five seconds for the Ac standby light to come on.

This Ac is supposed to work without a stabilizer but lot of people advised me not to run it without one.

Last edited by Gansan : 5th July 2020 at 15:39.
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Old 5th July 2020, 16:21   #6652
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Default Re: The home / office air-conditioner thread

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Originally Posted by anupmathur View Post
Indeed, they should be marked C20 or C25. The ones currently fitted are type B.
Quote:
Originally Posted by Gansan View Post
Thank you. In what way is a C type MCB different than installing a higher capacity B type MCB? Also, can high inrush current cause any problem to the Stabilizer or Ac over a period of time? This particular stabilizer does not have much of a delayed start. Once switched on, the timer runs from 5 to 0 and then it takes just another five seconds for the Ac standby light to come on.

This Ac is supposed to work without a stabilizer but lot of people advised me not to run it without one.
I was curious, so I Googled it:
https://thegrid.rexel.com/en-us/foru...rcuit-breakers
I didn't know this. Thanks @anupmathur
Quote:
Type B Circuit Breakers

Minimum trip current: 3 to 5 times rated current.
This type of circuit breaker is used for purely resistive loads, or loads with a very small inductive component.
  • Lighting circuits (non-inductive)
  • General purpose outlets
Type C Circuit Breakers

Minimum trip current: 5 to 10 times rated current.
This type of circuit breakers is used for loads with a moderate inductive component, typically electrical equipment which uses low-HP motors or specific types of lighting:
  • Air conditioners
  • Residential / Commercial Pumps
  • Fans
  • Lighting which uses ballasts with an inductive component
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Old 5th July 2020, 16:41   #6653
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Default Re: The home / office air-conditioner thread

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Originally Posted by Gansan View Post
Thank you. In what way is a C type MCB different than installing a higher capacity B type MCB? Also, can high inrush current cause any problem to the Stabilizer or Ac over a period of time? ...
...
This Ac is supposed to work without a stabilizer but lot of people advised me not to run it without one.
If the manufacturer claims the AC can run without a stabilizer, I, personally, would not use one. Also, it is dangerous to use a stabilizer that has no (adequate) time delay built in for run>stop>start conditions as happens in brief power line interruptions. The minimum 'safe' delay is about 2 minutes, usually built into the AC circuitry itself.

A large inrush current will not harm the equipment that is pulling in that current; it is designed to handle that. The stabilizer ought to be able to handle such currents as well, but you can never be sure. These stabilizers are invariably made on low budgets and can seldom match the quality of the AC itself. Moreover, many are being made by third party suppliers and are merely branded with the AC manufacturer's name. The stabilizer market is quite a scam, if you ask me!

I have not used a stabilizer with any of my ACs for the past decade (though none of my ACs claims it may be used without a stabilizer!); I use only a voltage protection device (Sollatek, 20 amps). These are good for over-voltage and under-voltage conditions (brown-outs), as well as limited lightning induced surge protection.

Last edited by anupmathur : 5th July 2020 at 16:42.
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Old 5th July 2020, 18:15   #6654
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Default Re: The home / office air-conditioner thread

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Originally Posted by mvadg View Post
I was curious, so I Googled it:
The quote doesn't make one thing clear. The MCBs are designed to handle the much higher currents for a limited amount of time. The pre-MCB equivalent was the slow-blow fuse. But it is for long enough time to trip the type B MCBs.

The start-up, in-rush currents or these devices like compressors and high-power pumps are so brief that it takes a multimeter with the specific capacity to capture and measure them to do so.
Quote:
Originally Posted by Prowler
But don't connect to the earth directly at the first instance. If there is a short to the supply in your ac, it would result in a fire incident
If a short to earth is sufficient to burn cables, shouldn't it trip the MCB?
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Old 5th July 2020, 20:22   #6655
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Default Re: The home / office air-conditioner thread

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Originally Posted by Thad E Ginathom View Post
The quote doesn't make one thing clear. The MCBs are designed to handle the much higher currents for a limited amount of time. The pre-MCB equivalent was the slow-blow fuse. But it is for long enough time to trip the type B MCBs.

The start-up, in-rush currents or these devices like compressors and high-power pumps are so brief that it takes a multimeter with the specific capacity to capture and measure them to do so.

If a short to earth is sufficient to burn cables, shouldn't it trip the MCB?
I'll let the experts chime in on your questions, but I found this informative video:
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Old 5th July 2020, 23:12   #6656
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Default Re: The home / office air-conditioner thread

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Originally Posted by mvadg View Post
I'll let the experts chime in on your questions, but I found this informative video:
Very interesting. Thank you very much!

I'd recommend also watching the following video from the same guy which explains the internal workings of an MCB. In a little while, I'll watch about RCBs as well
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Old 5th July 2020, 23:33   #6657
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Default Re: The home / office air-conditioner thread

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Originally Posted by promit View Post
The only option at the moment in the 1.5T inverter window type category seem to be LG and Voltas. We got two Voltas inverter units last year. Seem to be doing fine. Replacing another one shortly. I am thinking to not go in for the Voltas again. I have my eyes on this LG unit. Mainly for the retro looks and the advertised quiet sound rating. The extra tech features are an added bonus. What are your early impressions in terms of noise levels and your reviews on the app functions?


Thanks in advance!
Promit
The noise level is slightly more than my other Hitachi dual motor window AC. But definitely lesser than my previous Samsung. I measured the noise level in my room to be about 30-35 db when everyone was asleep (and since I was awake, no snoring ). Measured using one of the apps in the playstore so not sure of the accuracy. However, I expected more in terms of silence, given the 10 db difference vis-a-vis Voltas. Unless of course, the Voltas is terribly noisy as some reviews have suggested.

The wifi feature is very convenient since the remote is with the Mrs sometimes and I sleep with my phone handy anyway. The fact that the app shows the power consumption is good information.

PS: I didn't realise that the Voltas window AC is an inverter unit.

PS2: The LG I bought - the box says made in Thailand. The remote says made in China. I didn't check the unit.

Here is a real life pic.
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Last edited by Eddy : 5th July 2020 at 23:38.
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Old 8th July 2020, 14:02   #6658
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Default Re: The home / office air-conditioner thread

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Originally Posted by Thad E Ginathom View Post

If a short to earth is sufficient to burn cables, shouldn't it trip the MCB?
It depends on many factors - the upstream MCB and the internal resistance of the wires amongst others.
In our case, the MCB fitted was 30 A and the wiring was about 20 years old. The resulting current must have been less than 30 A and after a few minutes of such high current, the insulation burnt and started the fire.
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Old 8th July 2020, 15:12   #6659
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Default Re: The home / office air-conditioner thread

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Originally Posted by Thad E Ginathom View Post
If a short to earth is sufficient to burn cables, shouldn't it trip the MCB?

As @prowler has explained in below post, Single pole MCB is a inline mechanical device with bimetalic heating element and mechanical lock/release set up. By in line , i mean, its not connected to earth. In coming and outgoing wires are both phase wires. Sometimes when there is a short circuit (P to N/E), due to inherent internal resistance, the current is limited and does not reach trip current levels. That may be the reason why the cable insulation burnt while the MCB did not trip. It may also be a case of bad MCB. In such scenarios , a RCCB (or ELCB) would be helpful.

Quote:
Originally Posted by Prowler View Post
It depends on many factors - the upstream MCB and the internal resistance of the wires amongst others.
In our case, the MCB fitted was 30 A and the wiring was about 20 years old. The resulting current must have been less than 30 A and after a few minutes of such high current, the insulation burnt and started the fire.
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Old 8th July 2020, 15:53   #6660
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Default Re: The home / office air-conditioner thread

Big confession. I had little idea at all how an MCB works until I watched the video in this post by mvadg, and the following video on the same channel showing MCB internals. I just regarded it as the modern, resetable thing that replaced fusewire and cartridges. Not that that isn't right, but there is so much more to it. The bimetal strip provides a slow-blow function, but there is also a magnetic quick-blow function mechanism. I'll say no more, as I'll only confuse the issue: the videos are made by a real electrical engineer. Strongly recommended!
Quote:
Originally Posted by mvadg View Post
but I found this informative video:
Thanks again!
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