24 replies to this topic

[nvd650]

Hi there,
Please tell me pros and cons for both singe and double wiring for a UPS?
Thanks

[Pathfinder]

when i was installing homage ups (before that i used universal ups on single wiring for 3 years) and i called a very expensive and experienced electrician which AYS electronics(Homage distributors) saleman recommended me and i asked him that plz do double wiring for homage he said i wont benefit you single wiring can serve you well may be he was saving his time

[blogger]

Single line wiring is safe. Just want to share my personal experience with double line wiring. First time when I got UPS installed in my home, electrician gave double line to switch boards. Next time when I got some maintenance work at my home, new electrician connected some appliances with the neutral coming from the UPS and connected that neutral line to neutral of house. I accidentally reversed the direction of input plug of UPS and short circuit happened which burnt the UPS.

[nvd650]

Now credit goes to you or single line or double line? It can also even in normal case.....

[blogger]

No, it was electrician's fault who connected output neutral to home's neutral. When you do this you are bound never to reverse the input. He didn't tell me what he did and therefore, this happened.

Edited by blogger, 17 April 2012 - 12:03 AM.

[blogger]

All I mean to say, if it were single then nothing of this could happen. Well, its your choice what kind of wiring your prefer. I prefer single line wiring. I have tested this type of wiring and it came out to be safer.

[farhan_ds]

single line wiring is safe, but not recommended for APC or MG ups. local work great on single on double.

for imported UPS, you either need to ask the seller to make common the phase and neutral for single line connection inside the UPS.. or instead just get a one time double wiring and switch any ups at will anytime.

[signode]

Why safe??
I written following words in a thread;

"This is a very common practice in our country to lay only one wire from UPS to load and make common the neutral but this is ABSOLUTELY wrong. I saw an electrician got a powerful shock while doing work on neutral wire (of wapda lines) during WAPDA off because the the neutral of UPS operated equipment and neutral of other equipment was the same. I saw many other problems with such kind of wiring. So it is internationally recommended to completely isolate the phase and neutral of utility power supply from UPS.

So we should think the life of others not only save our money".

Edited by signode, 17 April 2012 - 10:10 AM.

[nvd650]

All I mean to say, if it were single then nothing of this could happen. Well, its your choice what kind of wiring your prefer. I prefer single line wiring. I have tested this type of wiring and it came out to be safer.

I guess other wise, if it was on double line then there is no issue for neutral at all because there is no connection of wapda neutral to ups neutral. and no chance of reverse connection or so :S
in single line it is dependent on wapda's neutral while on double wiring it is independent? what do you say? I mean in double do I need to use wapda's neutral? or care for the reverse connection and so on :S I'm confused...

[nvd650]

single line wiring is safe, but not recommended for APC or MG ups. local work great on single on double.

for imported UPS, you either need to ask the seller to make common the phase and neutral for single line connection inside the UPS.. or instead just get a one time double wiring and switch any ups at will anytime.

In single wire can you connect your ups for charging on wapda as you wish? let me explain you, though I don't have any wiring for one of my office, I simply connected ups to wapda and from output of ups an extension wire (multi plug or what ever you call it) and on that extension I've 3 of my PC's and ptcl modem + wifi router... now I don't care how my office boy connect the ups to wapda, while in single wiring you have to take care of this on both ends, at wapda and ups output as well......

Edited by nvd650, 17 April 2012 - 11:02 AM.

[nvd650]

Why safe??
I written following words in a thread;

"This is a very common practice in our country to lay only one wire from UPS to load and make common the neutral but this is ABSOLUTELY wrong. I saw an electrician got a powerful shock while doing work on neutral wire (of wapda lines) during WAPDA off because the the neutral of UPS operated equipment and neutral of other equipment was the same. I saw many other problems with such kind of wiring. So it is internationally recommended to completely isolate the phase and neutral of utility power supply from UPS.

So we should think the life of others not only save our money".

means only drawback in double wiring is extra expense on extra wire + the electrican ?

[signode]

One more loose point of single wire wiring;
If someone did the single wire wiring i.e. wapda neutral and UPS neutral is common and if any time for any reason some wapda electrician or any electrician working at your home DB, swap the incoming wires i.e. phase wire connect with neutral and neutral wire connect with phase, now imagine what happen; I saw some UPS kits burning cases while they did the single wire wiring.
SO ALWAYS ISOLATE UPS OUTPUT FROM OTHER EQUIPEMENT WIRING.

[Ijaz Ahmed]

If someone did the single wire wiring i.e. wapda neutral and UPS neutral is common and if any time for any reason some wapda electrician or any electrician working at your home DB, swap the incoming wires i.e. phase wire connect with neutral and neutral wire connect with phase, now imagine what happen;

Nothing will happen if someone reverses Live + Neutral entering into your home.

Imagine you don't have any UPS installed, now if for some reason your Live + Neutral entering your house are swapped, what will happen ?

However a short circuit may happen if you swap either the input of UPS or the output of UPS if common neutral scheme has been used. If you swap both the input + output of UPS, again nothing will happen. If one needs to use common neutral, then Input + Output of UPS are permanently connected with circuit breaker on both sides.


Do you know that neutral of all the houses/ offices on the same Wapda transformer is already common ?

[farhan_ds]

In single wire can you connect your ups for charging on wapda as you wish? let me explain you, though I don't have any wiring for one of my office, I simply connected ups to wapda and from output of ups an extension wire (multi plug or what ever you call it) and on that extension I've 3 of my PC's and ptcl modem + wifi router... now I don't care how my office boy connect the ups to wapda, while in single wiring you have to take care of this on both ends, at wapda and ups output as well......

Actually no. i have had a single wire set-up in home for 3 years and on my pc from last 5 years. and exactly in same way/. my pc ups is connected to wapda and from back, and extension to connect PC LCD Heavy Amplifier, wifi router and often a printer. all work well, on single wiring. and ups charges on wapda while outputs from battery in load shedding

same for house. UPS is connected to main DB for many full rooms. all wall sockets are working with any mobile charger or hair-drier or laptop chargers etc. also every main switch and bolt is also working fine.. again on single wire.

yesterday got whole house on double wiring, for using APC Ups, without converting them to neutral common single wire configuration. that way, now whole house is connected to them, and i can swap instantly between desi and apc ups any time due to double wiring

[nvd650]

Actually my logic was, why don't we use neutral of battery, no one telling me real reason. Can't we have extra backup this way (may be energy losses reduced in this manner).

Nothing will happen if someone reverses Live + Neutral entering into your home.
Imagine you don't have any UPS installed, now if for some reason your Live + Neutral entering your house are swapped, what will happen ?

[Ijaz Ahmed]

Actually my logic was, why don't we use neutral of battery, no one telling me real reason. Can't we have extra backup this way (may be energy losses reduced in this manner).

Neutral of the battery ??? Please don't mix up the terminology. There is no neutral wire in DC rather it is called Negative wire.

And really I didn't get your point, what you want to do with negative wire of battery to increase the back up time. Can you explain more ?

[nvd650]

LOLz yes you are right, +ve and -ve terminals. Current flow when circuit is completed. In single line wiring when you disconnect ups from main supply (unplug from charging) current stops flowing because it was using wapda's neutral to complete the circuit, right? but when we use double wiring, then no matter ups is plugged in for charging or not. Because circuit is complete now with the battery.... now what about energy losses in both cases?

[blogger]

I guess other wise, if it was on double line then there is no issue for neutral at all because there is no connection of wapda neutral to ups neutral. and no chance of reverse connection or so :S
in single line it is dependent on wapda's neutral while on double wiring it is independent? what do you say? I mean in double do I need to use wapda's neutral? or care for the reverse connection and so on :S I'm confused...

Let me clear something. When power is failed, input neutral of UPS becomes a common neutral for most UPS so appliances still work even if only output phase from UPS is provided to them. So, single line wiring is as much safe as double line can be. Problem happens only when you connect output neutral of UPS to neutral of home. This can lead to short circuit because live can come in contact with neutral if you intentionally or unintentionally reverse the input.. When power is failed, neutral of WAPDA also goes off. It is the neutral from UPS which makes the devices run because circuit is closed.

[nvd650]

@blogger, what do you think about energy losses in both cases, I don't think that it will be same. If we reduce energy losses, we'll definitely have more backup time, right?

[farhan_ds]

there are no significant energy losses in common vs separate neutral wire. the circuit switches only.