Too much surge protection?

Harry Bloomfield said:
Sounds a bit unlikely - not your story, but the reason for low IR.
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It would (sound unlikely) if the "leads" being talked about were just cables, but I suspect that he was referring to the "several extension leads which have surge protection" referred to in the OP, which, if they were connected at the time, could well result in a low IR.

Kind Regards, John
 
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Yes that's me. I have 4 leads with surge protection all connected to sensitive equipment. Now that I have an SPD fitted in the CU I intend to replace them with standard ones. It can't do any harm and anyway I have re-organised some of my stuff so I might get away with just 3. Any recommendations for good quality leads (I like each plug to have an individual switch to isolate monitors and printers when not in use whilst keeping routers and phones etc. available). I would like at least one with USB charging capabilities.
 
Harry Bloomfield said:
The simple, cheap version is a use once only - Once the surge protection has been used, they tend to blow and offer no further protection.
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The "simple, cheap version" is identical in parts that are in a CU based SPD - Simply MOVs and a gas discharge tube. The gas discharge tube is pointless in an extension lead since the inductance of the lead is too great for it to be useful.
 
bernardgreen said:
Can you have too much surge protection ? If the circuit is RCD protected ( Earth leakage ) then the amount of Earth leakage current created by the surge protectors could be enough to trip the RCD. Surge protectors ( or supply filters ) have capacitors between Live and Earth and between Neutral and Earth and these create Earth leakage current.
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Surge protectors have MOVs between all poles. Don't confuse them with EMI filters.
 
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Vicario said:
My electrician said that my leads were the cause of a low IR reading on the upstairs ring and that they could trip that RCD.
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You will get a low IR reading if testing at 500V with surge protected leads in place, but not at 250V. Why was he testing IR with everything connected?
 
Vicario said:
Yes that's me. I have 4 leads with surge protection all connected to sensitive equipment. Now that I have an SPD fitted in the CU I intend to replace them with standard ones. It can't do any harm ...
Click to expand...
Well if (unlike me!) you are convinced of the need for (or value of) 'surge protection' then to have both an SPD in the CU and surge protection in your extension leads would possibly be an advantage (since neither is going to be anything like perfect in 'suppressing surges').

However, as I've said, I am personally far from convinced that there is a particular need for either, so I'm probably not the right parson person to be 'giving advice' about it :)

Kind Regards, John
Edit: work of disobedient typing fingers corrected!
 
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aptsys said:
Surge protectors have MOVs between all poles. Don't confuse them with EMI filters.
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Very true, but I think you'll find that at least some of these fancy/expensive extension leads have filters as well as 'surge protection'. Some are probably even 'gold-plated', given that there is no limit to the gullibility of some markets :)

Kind Regards, John
 
JohnW2 said:
Well if (unlike me!) you are convinced of the need for (or value of) 'surge protection' then to have both an SPD in the CU and surge protection in your extension leads would possibly be an advantage (since neither is going to be anything like perfect in 'suppressing surges').

However, as I've said, I am personally far from convinced that there is a particular need for either, so I'm probably not the right parson to be 'giving advice' about it :)

Kind Regards, John
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When did you take holy orders John :whistle:
 
Thanks everyone for the very informative answers, especially to reverend John. What I take from all of this is that having 4 leads with surge protection could cause nuisance tripping of the RCDs in my new CU and it's probably a good idea to replace them. I forgot to mention that my electrician noted low IR on the upstairs ring, where all 4 are situated.
 
Just a thought. Is it the neon on the lead or the surge protection bit that can cause issues? Should I avoid all leads with neons when choosing my new leads?
 
MOVs are a pretty standard component in any electrical device connected to the mains nowdays...and I've seen many destroyed on boiler circuit boards. It's impossible to tell whether they have saved the board in the past by clamping the surge...I only get to see them when the surge has too much energy and the board dies.

Here's a £2500 commercial boiler fan...the MOV couldn't save it...the little fan's from a domestic boiler.

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D

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A

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Vicario said:
Just a thought. Is it the neon on the lead or the surge protection bit that can cause issues? Should I avoid all leads with neons when choosing my new leads?
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The neon - a neon warning light, just presents a tiny load across the L and N, just like any other load really - so not a problem. The extra surge protect, might cause RCD trips, so avoid those.
 
Gasguru said:
MOVs are a pretty standard component in any electrical device connected to the mains nowdays...and I've seen many destroyed on boiler circuit boards. It's impossible to tell whether they have saved the board in the past by clamping the surge...I only get to see them when the surge has too much energy and the board dies.

Here's a £2500 commercial boiler fan...the MOV couldn't save it...the little fan's from a domestic boiler.
Click to expand...

The have very limited ability to cope with surges and do tend to self destruct when faced with any serious surge, often leaving the circuit they were intended to protect, with no surge protection at all.
 
D

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