Two SPST relays in place of a DPST relay?

Thread Starter

cherynk

Joined Feb 3, 2016
1
Are there any issues using two SPST relays instead of a DPST relay? I am running a 220 load through the relay and bought the wrong thing. A DPST is more expensive than two SPST so I figured Id just buy another SPST and run each leg through a separate SPST relay. The relay control is 12VDC. I would run these in parallel rather than in series, correct? There wouldn't be any issues with one relay connecting before the other, right?
Thanks for your help.
 

MrSoftware

Joined Oct 29, 2013
1,618
Your MTBF will be lower since you have double the mechanical parts (greater chance for failure), if that's a consideration.
 

mcgyvr

Joined Oct 15, 2009
5,394
There wouldn't be any issues with one relay connecting before the other, right?
There "could" be..
But if you are just using the relays to switch each side (Line/Neutral) then it won't matter..

Even double pole relays can have one pole that fails to switch while the other is just fine.. (VERY common on "low cost" relays... virtually non-existent on a quality relay like Omron)
 

MaxHeadRoom

Joined Jul 18, 2013
19,466
If 200v 1ph (L1&L2) as in N.Am. then you can switch both sides, if 220vac L1 & N then the N is not normally switched (or fused).
Max.
 

eetech00

Joined Jun 8, 2013
1,743
You should consider the failure modes of your circuit. What if one relay energizes but the other doesn't? Not saying it's a problem but should be considered.
 
Top