# Interest group forums > Electrical Contracting Industry Forum > Electrical Load Shedding Forum >  GENERATORS?UPS?INVERTERS?

## QUINN

Does anyone on the forum have any info or experience with any of the above?
I would like to know what other businesses are using or what they are looking at.
Any pro's and con's I should know about.
As I understand it a ups will last or only a few minutes but I am told with new technology they can last for days and are better than generating power all the time.......any advice please

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## duncan drennan

What exactly do you want to power?

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## Dave A

If it's computers, even if you go with a generator, you're going to need a UPS with inverter to control the supply anyway. As for how long a UPS can keep you up for - well that depends on the load and the storage capacity of your batteries.

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## Ryss

It order to keep a whole office running with all the desktop workstations will mean that the UPS will require its own power circuit routed to all work stations. If you are located in Gauteng. This may be worth while as it will also lessen damage caused by lighting strikes. Maybe cover the switchboard as well.

However the UPS will have to be huge to power the system for an extended period of time. 

Normally I used a UPS (a UPS has a built in invertor and batteries) which was linked to the servers, so that it would keep the servers going, while they initiated an automatic shut down, This occurred within 20 minutes. So 20 minutes to a hour I would say.  

If you want to protect workstations from data loss and remain up and running for longer than that, then the UPS can be powered from a generator  The size of the generator and the UPS will depend on the total KW's that all the equipment in the server room, all the workstations, and switchboard need.

When we started having the power outages in Cape Town, I arranged a temporary situation with a generator (an industrial generator/welder, they may be cheaper per KW and may have a better resale value) and a network of extension leads to reach the workstations. ('n Boer maak a plan) This was only used once

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## apropos

I can recommend PSS Distributors to help you with all your UPS and back-up power needs.

They provide good quality products at reasonable prices, with advise, service and maintenance staff available on your doorstep.

See this link to calculate your needs:
http://www.powersystems.co.za/configurator.php

or contact Wayne Woolley at
Johannesburg Branch
P.S.S. Distributors c.c.
P.O. Box 4113, Edenvale, 1610
5 Diagonal Rd, Eastleigh, Edenvale
Telephone: (+2711) 452-4059
Facsimile: (+2711) 452-4088
e-mail: sales@powersystems.co.za

I know they would be glad to help! :Big Grin: 
Regards
Genevieve

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## murdock

here are some tips:

firstly you can use a ups or an invertor with a whole lot of batteries to provide power to your home or office...it is a quieter but more expensive option...and when the batteries go flat you need power/generator to charge the batteries...some people dont have a choice because they live in flats so a generator is not an option...be carefull with batteries not to short them out...and remeber they are full of acid...make sure they are sealed and enclosed properly...and kept away from children.

i always advise my customers to use an online UPS to protect their computors...servers...and any sensitive electronic equipment (the one which has built in surge protection)... regardless of load shedding or not...connected directly to all the red or dedicated plugs.

i have one customer where i installed a big unit to run the entire office more than 10 years ago...they were having problems loosing data so i connected a big online unit it cost a lot of money but still to this day the UPS is running and they have had no problems with data loss due to dips and swells or surges in the electricity supply saving them lots of money in data loss and computor replacements 

now with the load shedding you need to make sure that the UPS has a frequency tolerance of at least 45 to 55 hz if you want to run the UPS from a generator...and then you will ask why...well the cheaper generators have the buzz word at the moment "AVR automatic voltage regulation"...you do need voltage regulation but the problem is with the frequency which can go as high as 54/55hz when the generator is not under load...and some of them drop as low as 46 hz...if the UPS is old or not designed to with a high torence then it will just keep switching off line...

buy a couple of small 2 tube fluoresnt light fittings and switch it to 1 tube and you should get 3 -6 hours...dont buy the osram green camping light they are a waste of money the batteries dont last...and make sure the light has a charger which will not over charge if left on charge...electric world has a good light for around R115 on special.

whatever you do dont plug to plug your generator in your house...it is extremely dangerous it overides all the safety devices in the distribution and can cause a dangerous enviroment for electricians working on the lines..the cheapest most pratical way to do it is to fit a manual changeover switch with an ammeter to determine how much power you have available...lets say you fit a 5 kva which is the most common one for your house...if you have a annalog ammeter you can run the tv fridge etc...then if you need to run the pool pump and the kettle for example you switch off  some of the appliance then switch on others watching the ammeter needle when it reachs the limit marked with a marker pen on the ammeter you stop...just remember resistive loads like the kettle...geyser...toaster are have consistant loads but fridges...pool pumps...have start up currents which you need to allow for... so dont let the needle sit on the line...allow 5-10 amps for start up or if you hear the generator battling reduce the load by switching off more appliances. 
be even more careful with the positioning of the generator it will kill you slowly without you even knowing if the fumes get into the house...so whatever you do dont run the generator in a garage or next to a window...preferably get someone to extend the exhaust just above the roof height...heat will rise.

also be careful of generator installers...every one and their uncles are installing generators now like aircons...there are a lot of fly by nights making a quick buck...make sure the installer is registered or you will have safety problem...there are no regulations for generators yet only guide lines...but the cable selection and changeover panel and labelling need to be up to spec...warning the electrician that there is a generator connected to the DB.

you should be sorted if you have the following items at home:

a solar heated geyser
a gas hob 
battery emergency lights positioned correctly...connected directly to the mains/generator with a switch for when you go to bed
an online ups or 2 with surge protection for sensitive electronic equipment and alarm connected to the mains/generator...
and if you can fit an additional battery for your gate motor
a 5 kva generator preferably diesel more expensive but should last longer and be more stable (i havent had a chance to test a diesel one yet for voltage and frequency stability) with an analog ammeter and a volt meter.

or if you have R80000.00 we can just fit a big unit and it will switch on automatically when the power goes off will run the house as if there was never an outage...just fill the diesel...and for a small fee we will service the unit at the correct intervals as per the running hour meter.

if you have a small office:

have a load assesment done...to determine the size of the ups required and the amount of batteries neede to keep the office running for the load shedding period of 2/3 hours or a  generator to keep the ups batteries charged and so that you dont loose data...it is not advisable to run a generator directly connected to your computer 

an oline surge protected ups with your computor...telephone...server...small printers connected..."not big printers" to keep the office running without any disturbances...an online is is more expensive but if you dont want to loose data it is a better choice especially for critical aplications.

fit emergency lights with at least 6 hours backup time and over charge protection


big companies 

get a company to do a load assesment (recording over a period of time not less than 8 hours/1 day)which will give you a good idea of the power consumption and give you professional advice on ways to keep you up and running.

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## murdock

PREPARE FOR WINTER or its gona be a cold one if you dont prepare...dont say you werent warned

remember the oil...element heaters...electric blankets...aircon heaters.

remember it stays dark later in the morning and gets dark earlier in the evening.

and it takes more hot water to heat up the bath.

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## Dave A

> also be careful of generator installers...every one and their uncles are installing generators now like aircons...


Bottom line - Insist on an electrical Certificate of Compliance for the installation.

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## Debbiedle

Thanks for the info Murdock

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## murdock

i am busy quoting to install a 1 megawatt generator ooouuuch.

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## Dave A

That'll keep you out of mischief! Hope you get the job.

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## Upstairs

Get a generator. Make sure the regulator is suited to your requirements. You cannot run a computer on any generator.Some makes are not that good and can damage your equipment. Stay away from Chinese makes. I would suggest that you do not have it wired into your DB Board, but go through a seperate DB with its own plugs. Prevents accidents when power is restored and cheaper. Your electrician can do that for you.Alternatively you can have a change-over switch installed in DB.

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## Dave A

Welcome to TFSA, Upstairs  :Wave: 

I've been wondering about the "don't buy Chinese generators" story. I've heard it a few times now, and I have to wonder where it comes from.

A business partner of mine compared prices between a "known brand" dealer and an "non-branded" generator retailer and he found the "non-branded" retailer was about 25% cheaper than the "brand" dealer on what seemed to be exactly the same machine. 

The dealer's explanation? The "opportunist" was selling Chinese made machines made under licence from the brand, but _his_ machines came from the Land of the Rising Sun - hence the higher price.  :Confused:

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## Pieter1

I sit with more or less the same problem.  I have a 2.5kva made in china (Ryobi) generator without a AVR and plan to run 2 PC's from it.  The measured Volts is 250-260v without load with nothing attached (no idea on the Hz output).

My options are to take it back to GAME and declare it a no-deal or to keep it and run it with a UPS (600w), linked to the PC's.

Anyone to help me decide?

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## Dave A

> I have a 2.5kva made in china (Ryobi) generator without a AVR and plan to run 2 PC's from it.  The measured Volts is 250-260v without load with nothing attached (no idea on the Hz output).


Hmm. I think you've just answered my previous post.

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## Dave A

Pieter - Have you taken a voltage reading when the generator is under a steady load?

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## murdock

make sure the ups is an online one and will work with the generator...

take a look at the images of a recording i did for a short period of time on a petrol generator...37 transients occurred in matter of couple of minutes...this what kills your sensitive electronic equipment...unless some one can show you a pictures like these on their test equipment dont believe any cr*p you hear about AVR and pure sine waves...ask them to produce a recording of their generator or ups or invertor taken while running at your site or office not one they have downloaded from a web site.


be careful these are crazy times and every person his uncle and mother in law are trying to unload generators...ups and invertors...unfortunatley we the public are paying for the eskom/goverment fiasco in more ways than you know...penalties on using electricity????  interest rate hikes ...high inflation ...soon the water problems??? what next??????

you ask yourself why are we always the ones who always have to suffer for other peoples mistakes....

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## deon43

Hi all Iâm new on the forum but an old hand around the block! To the question on solar equipment and the functioning of these systems for backup there are a few important factors"
1. Generators are stinking, noisy convertors of expensive fuel to noise and is very bad to our environment with the gasses they release, so if you want this and like stink air and pay like crazy for fuel, get yourself a piece of this crap!
We are from the 21st century guys and girls, didnât you know the world has something like electronics? And who says it is expensive? Well this is a total misconception and a real argument for people that canât do analysis over a time period, if you take a time span of one year; I bet you will be better of with a UPS Solar system!! Ya Ya there is always the guys and girls with the question marks on the forehead not understanding, so let me help a bit as this is my speciality, making power to use from the sun.

Q, Why is invertors so expensive? 
A, In South Africa, ripping off people became a game and creating a total negative on some products. Iâve seen companies buying these units and good ones from abroad for about R1000-00 on a 1.5KVA pure sine wave with 93% efficiency and itâs been sold in South Africa for a small amount of R4500-00, thatâs what I call a RIP OFF!!
Q, what should I be careful when buying a Inverter for
A,   1. Make dead sure this is a pure sine wave inverter as Square wave units will damage anything that has a Motor drive like a fridge and some other equipment
      2. Make sure this is a good system with efficiency of at least around 90%; remember the leftover % is wasted power used
      3 Make sure the unit fit for the application, for computers an online but for lighting a relay transfer will be good
      4. If it is used for standby lighting or online backup make sure the Charger inside the unit (Must have one inside or you have to buy a external 
One) is capable to recharge the unit batteries in at least 8 hours. External battery systems give you the advantage in making the battery capacity bigger for longer backup
     5. The most Important is donât believe all the crap people tell you about the invertors either ask real experts or learn the info yourself by getting it from the net. Inverters are and will be the better solution in backup; you can have 10 min or ten days backup, your choice, energy come from a source the bigger the source the longer the time

Any person is welcome to contact me and Il gladly give them some info, keep it short please and hi wise guys out there who knows everything, please Iâm not here for arguments about how much you know but to help these who is in the dark, lately a lot by Escom, the angel of darkness, lol

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## murdock

ups solar systems...i looked into this system for some of my customers but at the time... costing and capacity were the 2 issues taken into consideration which made me consider other options...

give us some sort of ball park figue what it would cost to rig up a 2 kva system with an 8 hour run time and  a charge time of 10 hours...lets say the units are 10 metres apart...how long would it  take to recover from the cost of this type of installation.

i have found adverts all over the place with R75- R150 per month saving...phone your geyser...knows your geyser status...etc...etc...problem is this unit costs R2000 + installation...just to let everyone know you can buy a heineman timer with a battery reserve which has a 20 amp switching relay which means you can switch a 4000 watt geyser for as little as R600+ installation (they clip directly into the DB so the installation cost is min.)

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## Bransby

hi guys and girls

I have heard that I cant run my UPS's off of my inverter. is this true? i have 2 servers running off 350w power supplies and both have UPS's and my inverter is a 1200w. 

can anyone help?

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## Dave A

If your inverter isn't producing a pure sine wave, you'll probably have problems  :Yes: 

I've had situations where the UPS wouldn't accept power from a generator, let alone an inverter  :EEK!:

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## Bransby

how will I be able to check or should I call an electrician in?

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## deon43

Hey Guys and Girls, please post your enquiry on what you need and what application you want to drive e.g. the load or devices and for how long you want to sustain the power backup, Inverters are obvious the correct way to go as they are silent, noiseless, smokeless and on and on and very reliable. We are professional engineers on this applications and we do units from 600 watt up to 285 KW with online or offline technology. note the two differences, a inverter and a ups are quite different as UPS units, unless specified otherwise are shorterm backups and mostly âKwasiâ wave or as the public calls it Square wave (A step related formed sine wave, looks like staircase and bad for inductive equipment) and really very inefficient and bad for any system. We believe in making use only of Sine wave inverter equipment and with the high production volumes it does cost more or less the same these days as the Cheaper Square wave crap of earlier. Good advice, do it correct the first time and get a reliable supplier!! You can mail me on deon@electro-web.co.za and we will gladly help. :Detective:

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## Dave A

> how will I be able to check or should I call an electrician in?


An electrician might help, although not many have the sort of equipment needed to analyse the wave shape. You could test to see if the UPS will accept the power from the inverter. In fact, when setting up any backup power situation it's a good idea to proactively test it and not just wait for a crisis to occur.

Ultimately you probably need to be looking at your overall backup power strategy. Why do you need a UPS running off an inverter supply in the first place?

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## deon43

:Slap:  :Slap:  :Slap: Checking if a inverter/UPS if not specified in the specification sheet can only really been done by means of a Oscilloscope, most electronic guys have such equipment, TV repair shops Radio repair shops and so on. Funny enough is that Sine wave inverter manufacturers are proud of their products and thus have no problem on adding Sine wave inverter on the description. If not mentioned directly on the Info pages or specification, be careful, that probably the real reason why not mentioning it and selling it cheap, lol Keep on buying until you learn to do the right thing and read the info! Most reliable inverters have a pre-power stage we call a Power Factor correcting circuit which serve a double purpose inside the inverter, firstly to make sure it can run at a good Power Factor of at least 0.9 that makes the system very efficient and secondly it compensate for input power fluxuations, thus it will easily work also from a generator. Good recommended quality worldwide systems are the Cotek systems (only inverters not Ups all sine wave) very expensive and the "POWERVERT" systems (UPS and inverters all sine wave) very good and relative cheap but only available from June onwards in SA.

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## Daves

Hi all, is this forum still active? 

daves

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## Dave A

With Eskom saying it's going to take 5 years to get more generation capacity online and existing reserve generation capacity tight, I don't think the crisis is over  :Stick Out Tongue:

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## murdock

> Checking if a inverter/UPS if not specified in the specification sheet can only really been done by means of a Oscilloscope, most electronic guys have such equipment, TV repair shops Radio repair shops and so on. Funny enough is that Sine wave inverter manufacturers are proud of their products and thus have no problem on adding Sine wave inverter on the description. If not mentioned directly on the Info pages or specification, be careful, that probably the real reason why not mentioning it and selling it cheap, lol Keep on buying until you learn to do the right thing and read the info! Most reliable inverters have a pre-power stage we call a Power Factor correcting circuit which serve a double purpose inside the inverter, firstly to make sure it can run at a good Power Factor of at least 0.9 that makes the system very efficient and secondly it compensate for input power fluxuations, thus it will easily work also from a generator. Good recommended quality worldwide systems are the Cotek systems (only inverters not Ups all sine wave) very expensive and the "POWERVERT" systems (UPS and inverters all sine wave) very good and relative cheap but only available from June onwards in SA.


if the person selling the equipment cant provide the equipment to test...best you find someone who can...how do they verify the equipment they are selling is correct and functioning correctly during commisioning.

Now is a good time to enquire about generators and invertors cause most of the fly by nights are out of bussiness or found other opitunities to make quick money.

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## SeanM

Evening All

I recently install a 5kva hybrid inverter upon doing my test I noticed that when the installation was being fed from the grid all my sockets tested as they should and the earth leakage tripped at 20 ma. When I changed over to the inverter my polarity tester indicated that the earth was now missing from the socket circuits.

I then proceeded to test on the input to the inverter:

L-N = 235 volts
N-E = 0 volts

On the output of the inverter:
L-N= 230 volts
N-E = 90 volts

I then switched the inverter off and had the grid power still feeding the inverter

Input:

L-N = 235 volts
N-E = 0 volts

Output:

L-N = 0 volts
N-E = 24 volts

It seems that the inverter is faulty.

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## GCE

Hi SeanM 

It appears that your inverter output is not isolated from the input .

You need to earth the neutral on the output when it loses the grid and remove the earth under grid operation.In the higher quality units , the output is isolated from the input whether it is in grid or back up mode.

Make sure that the output is not earthed when on grid mode as you could become the star earth point for the transformer feeding the street under a fault condition , or if somebody steals the earth neutral link in the sub station.
It is why you have to install 4 pole change over switches on back up equipment and the reason for 6.1.6.

Basically *only the supplier can earth the neutral* - When you use municipal supply , they are obviously the supplier -  when you are in back up mode , you are the supplier.

_6.1.6 The neutral conductor shall not be connected direct to earth or to the
earth continuity conductor on the load side of the point of control except as
allowed in 7.16.4_

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SeanM (12-Feb-19)

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## SeanM

Morning GCE

Thank you for the excellent advice, I have stared the neutral and earth on the output and all is as it should be.

This has been a very interesting installation in the SANS 10142-1 pg 363 (Annexure P3) this is for UPS, The only alternative supply that does not get a star point is the ups setup.

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## ians

An interesting point to be noted for those who have an auto change over switch connected to a generator...load shedding at 10 pm when nobody is at the office means the generator will be running for the off period for wasting diesel...for some this could get expensive especially if the power is off for longer than 2 hours...money down the drain.

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AndyD (23-Mar-19)

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## ians

Reading through this thread...how things have changed.

Solar has become more affordable...and you can buy directly from China.

Inverters can now be grid tied...linked to solar panels etc.

Batteries are more expensive (a lot more) but with lithium the buzz and people offering 15 plus years life .

Generators...can be a smooth pure sine wave seeming switch over...with displays offering everything from a pure sine wave to current...power and even harmonics.

all you need is a second bond R100k plus and you can be enjoying the 2 hours loads shedding with your lights on and internet access...or you could save a R100k plus and enjoy 2 hours of quality time with the family playing board games or interacting with other humans face to face.

Something to think about before you rush out and take a second bond...all your electronic devices including your router generally have a 2 hour plus backup battery on board...so you can still share you isolated life behind the screen for the 2 hour load shedding period.

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## SeanM

Evening All 

I have been installing a lot of inverters with batteries and my challenge is indication lights for samite DB's, they don't make them. I install a seperate box next to the existing DB not a pretty site.

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## Eugeworx

> Evening All 
> 
> I have been installing a lot of inverters with batteries and my challenge is indication lights for samite DB's, they don't make them. I install a seperate box next to the existing DB not a pretty site.


Greetings my fine electricians, glad to have become part of this forum,, 
With regards to a basic 3kw inverter/2battery  setup: How are you guys installing the Power-On-Indication light for the essential circuit, so that to indicate to the user, that power is now running on the backup system?
If my understanding from the SANS UPS drawing fig.P.3, pg 360 is correct.

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## ians

> With Eskom saying it's going to take 5 years to get more generation capacity online and existing reserve generation capacity tight, I don't think the crisis is over


@Dave ...you mentioned 5 years .... eeeeeish

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## ians

> Greetings my fine electricians, glad to have become part of this forum,, 
> With regards to a basic 3kw inverter/2battery  setup: How are you guys installing the Power-On-Indication light for the essential circuit, so that to indicate to the user, that power is now running on the backup system?
> If my understanding from the SANS UPS drawing fig.P.3, pg 360 is correct.


The part number from my favourite supplier MCE (the worse 4x4 switch grid plate) page 139 of their catalog ... part number KCI-1L-G or r or what ever colour you desire ... I use green next to the main switch for mains power and red next to the inverter section of the DB ... that way if there is load shedding the green light is off ... but the red light is on ... if both are off then you know you have a problem or your battery is flat and there is no sun.

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## Dave A

> @Dave ...you mentioned 5 years .... eeeeeish


I see that was in 2009  :Stick Out Tongue: 

We were so young and naïve back then  :Roll Eyes (Sarcastic):

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## ians

Dont joke ... I went for a hair cut ... eeeeish normally a number 2 clears all the grey ... even the beard has had to get cut off ... only grey  :Frown:  ... I have removed all the mirrors in the house ... I amost shyte myself when I see the old wrinkled fart ... my mind still things I am 20 ... body tells me I am past 60 and the mirror makes me look 80+  :Frown:

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## Eugeworx

> Evening All 
> 
> I have been installing a lot of inverters with batteries and my challenge is indication lights for samite DB's, they don't make them. I install a seperate box next to the existing DB not a pretty site.





> The part number from my favourite supplier MCE (the worse 4x4 switch grid plate) page 139 of their catalog ... part number KCI-1L-G or r or what ever colour you desire ... I use green next to the main switch for mains power and red next to the inverter section of the DB ... that way if there is load shedding the green light is off ... but the red light is on ... if both are off then you know you have a problem or your battery is flat and there is no sun.


Good info, makes sense. Thanks Alot.  :Smile:

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