Sizing a safety disconnect switch

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chuongngh

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My customer wants to use an existing safety disconnect switch 4-pole, rated at 1200A ( continuous rating) with 2 adjacent poles in parallel to control a load 2000A. (voltage is no problem). In addition, the disconnect switch have to control a load 4000A for 1 minute.
Is this request acceptable ?

Thanks a lot for replying
 
Question about safety disconnect

Question about safety disconnect

Question is about current carrying capability of the safety switch.
The spec. of switch :
rated current: 1200A,
pole: 4-pole.
2-poles in parallel to double current carrying capability.

My question is that:
Is the switch able to carry a current
- 2000A continuously ? ( i think: Yes)
- 4000A for 1 minute ? ( not sure)

Thank you.
Chuong
 
My question is about overload condition for 1 minute

My question is about overload condition for 1 minute

barbeer said:
I am not clear of what you are asking?!
Click to expand...

My question is about current capability of safety disconnect switch.
The Spec. of switch :
Rated current : 1200A ( continuous)
pole: 4 pole
2 adjacent poles will be connected in parallel to double the current carrying capability of the switch.

My question is that:
1/ Is the switch able to carry a current 2000A continuously ?
I think it is OK. Because 2 x 1200 = 2400A
2000 x 1.15 = 2300A
2/ Is it able to carry current 4000A for 1 minute ? ( overload condition)

The switch manufacturer could not answer my question at the moment.
For safety disconnect switch,we do not have time-current curve as it is available for circuit breaker device

Thanks for your reply
Chuong
 
Question about safety disconnect

Question about safety disconnect

Very sorry for my unclear question.
Now:
We have a switch 1200A-4poles
I connect poles in parallel as following diagram:
On each side of Load and Source, there are two pairs of poles connected together.
______________
|o| |o|--------
------|o| |o|
Source | | Load
|o| |o|
------|o|____________ |o|--------

This parallel connection diagram is to increase current carrying capability of the switch.
Is this switch in the diagram able to provide 2000A .
 
Will it work? Probably.

Is the device UL listed or this use? Probably not.

Is it code compliant? Only if it is listed for that use.

If something goes wrong, for what ever reason, will you be held accountable and will there be lawyers? Most definitely.

My experience has been some owners can be too cheap for their own good, then when things go wrong and it costs you money they suddenly want it done right and cost is no issue because you are the licensed electrician and should have known better.

Whoo hooo first post!
 
Sure it may carry the amperage.

But will it INTERUPT (Disconnect under load) ? Naaaa. One pole will open before the other.

Will it be able to carry 4000A for 1 minute ?

You say the manufacture doesn't know. They don't test it at that amperage. Think about it.

But let's get back to basics. It's rated at 1200 amps. Period. Where did that "( continuous rating) " spec you keep mentioning come from ? Why do you feel it's important to mention ?

You haven't told us the mfg/model #, what the application is, what voltage, etc. I'm guessing it has something to do with battery/UPS ?

Anyway, I'll come right out and say it: no No NO !!! It is not rated for doing that. So tell your customer: NO.
 
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