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Galvanic Isolator Cable


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Just now, rusty69 said:

Are there any uk sold in line ones that do? 

Yup, Sterling ones I believe. 

1 minute ago, rusty69 said:

Are there any uk sold in line ones that do? 

I read what you wrote and pretended it was English ;)

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10 hours ago, jonathanA said:

Yep and just as irrelevant....

Not really. It is an internationally recognised standard and there isn't an equivalent over here. The relevant bit is about tolerance of a live short to earth resulting in a very high current through the diodes. If they blow open circuit, you no longer have an earthed hull. The ABYC spec aims to make sure this doesn't happen.

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2 hours ago, nicknorman said:

Not really. It is an internationally recognised standard and there isn't an equivalent over here. The relevant bit is about tolerance of a live short to earth resulting in a very high current through the diodes. If they blow open circuit, you no longer have an earthed hull. The ABYC spec aims to make sure this doesn't happen.

I'll contend that a decent GI is far safer than a boat based IT, with the latter a steel hull has no connection to shoreline earth, therefore no protection from chafed shorelines.

I'm still waiting to see proper evidence of a decent IT with blown diodes actually happening in the wild, there's been anecdotal mumblings but from commercial parties with an interest in selling £££££ kit.

IME large diodes melt short before they blow, which probably needs quite a high multiple of their surge rating...

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57 minutes ago, smileypete said:

I'll contend that a decent GI is far safer than a boat based IT, with the latter a steel hull has no connection to shoreline earth, therefore no protection from chafed shorelines.

I'm still waiting to see proper evidence of a decent IT with blown diodes actually happening in the wild, there's been anecdotal mumblings but from commercial parties with an interest in selling £££££ kit.

IME large diodes melt short before they blow, which probably needs quite a high multiple of their surge rating...

Seconded

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1 hour ago, smileypete said:

I'll contend that a decent GI is far safer than a boat based IT, with the latter a steel hull has no connection to shoreline earth, therefore no protection from chafed shorelines.

I'm still waiting to see proper evidence of a decent IT with blown diodes actually happening in the wild, there's been anecdotal mumblings but from commercial parties with an interest in selling £££££ kit.

IME large diodes melt short before they blow, which probably needs quite a high multiple of their surge rating...

As I have said before, I spent my career in the critical power industry.

We used to monitor all equipment failures and analyse the results.  Wound components, (transformers, inductors, etc) used to fail far more frequently than the power diodes or power transistors. 

 

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22 minutes ago, cuthound said:

Wound components, (transformers, inductors, etc) used to fail far more frequently than the power diodes or power transistors. 

Presumably failing OC most of the time?

I.E. Failing safe?

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6 minutes ago, rusty69 said:

Any clues to which are the decent ones available in the uk?

The Sterling ones comply with the ABYC specs I believe, and as the best specification around I’d only consider one which does. 

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53 minutes ago, rusty69 said:

Any clues to which are the decent ones available in the uk?

The safeshore ones with LED status monitor should be pretty decent, as Tony says Sterling do an ABYC standard one but I don't know if they have an LED status monitor, if not I'd rather go with one that does.

Personally I'd only mandate an isolation transformer over a GI for a narrowboat where the boat will be left unattended on shoreline for months on end, with no one to keep an eye on the GI status LEDs.

As for the OP, maybe there's a reasonably knowledgeable friend/neighbour that could help install a galvanic isolator if not confident to do the job herself, that said the safeshore helpline seems to be pretty good by all accounts, maybe worth phoning them up and see what they say?

Something worth mentioning in passing is that a boat built from poor quality steel is going to be more vulnerable to rust, and an iso transformer or GI isn't a cure-all for that.

Edited by smileypete
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30 minutes ago, smileypete said:

Sterling do an ABYC standard one but I don't know if they have an LED status monitor, if not I'd rather go with one that does.

Because the ABYC spec requires the unit to fail safe, Sterling GIs which comply don’t require a status monitor. The cheaper ones which don’t comply with that spec do have a status monitor. 

https://sterling-power.com/collections/zinc-savers/products/zinc-savers-galvanic-isolators?variant=897122451

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