Electrical Supplier for RCD and Galvanic Isolator

TwinRudders

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Hi,

Maybe obvious - but any suggestions for mail order electrical supplies.
I need an RCD, Shorepower socket, galvanic isolator, plus cable etc.

Thanks,

Jono

PS Thanks to all for the advice about foam - just had all the cushions done by HM FOAM in Calne. Looking foirward to sleeping on the boat now! Luxury... They cut it all, even the angled sides and refitted covers etc.
 
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Anonymous

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Re: Could try here...

The price of a galvanic isolator from JG Technology looks good. I was reading up on the concept of them recently; do you know whether there is an laid down spec for the characteristics or does each manufacturer simply produce whatever he wants? I've never seen data included in the ads or catalogues for galvanic isolators - apart from maximum currrent, of course.
 

VicMallows

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For the RCD, MCB etc have a look at ScrewFix. A 'Shower' or 'Garage' unit is often a cheap/ convenient way to buy the RCD and small enclosure suitable for one or two MCBs, though you may need to change the MCB for suitable rating. You won't get the galvanic isolator from there though.

Vic
 

pvb

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I\'d imagine that......

I'd imagine that most galvanic isolators simply consist of two pairs of diodes, each pair wired in series, and the pairs then wired in parallel in opposing directions. This allows AC to flow but gives a block for DC electrolysis current below about 1.2v. Some of them include a capacitor, but this is by no means essential. The diodes need to be rated at least at the current capacity of the supply.
 

aidancoughlan

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for marine electrical supplies try ....
www.onboardpower.com
www.indexmarine.co.uk
www.merlin-equipment.com
www.ecsmith.com

RCD's do seem to be cheaper at hardware stores, and the outdoor ones should be waterproof etc., but check that it is a 'double-pole' RCD (I think that's what it is called?) - afaik, this cuts both sides of the circuit at the same time + and -, providing extra protection if you plug into a marina supply which is wired wrong - ie. it would cut the negative instead of the live wire in this case.
 

VicMallows

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Valid enough point, but have never ever come across one that only had a single-pole switch? perhaps some plug-in types, though would still be surprised. Of course by definition the detection has to be two-wire. (you are not perhaps thinking of the ancient earth trips which measured the fault current in the earth wire?).

Vic
 

aidancoughlan

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Hi Vic,
I read the 'double-pole' thing somewhere in Alastair Garrod's "Electrics Afloat"... I've gone back to check & it's actually a reference to the MCB (mini circuit breaker) that often comes bundles in the Consumer unit box with a RCD , rather than the RCD itself.

He says... "Whatever type of breaker is used, it is essential to make sure that it is a two pole variety. Household CB's are usually single pole breakers, meaning that as a result of a fault condition only the live circuit is broken. If such a breaker were adopted aboard a boat with a reverse polarity situation, then the breaker would operate on the neutral side of the circuit. Although still available to work effectively as a switch, the appliance would unfortunately remain live and potentially harardous. clearly two-pole CBs or 'phase-and-neutral' CB's cut both the live and neutral lines simultaneously, rendering the circuit safe irrespective of polarity.."

He makes a point of the above in relation to the MCB, but doesnt mention anything similar in relation to the RCD. Thinking about it, since they both trip the circuit (albeit for different reasons), should it apply to both? - maybe RCD's are normally all two pole anyway as you suggest.

ps. In case it aids identification when purchasing, he also refers to a breaker that breaks both sides of the circuit in a side-note as a "Type-C" breaker.

regards,
Aidan.
 

VicMallows

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Yes, I can see the reasoning (double pole MCBs). But my personal opinion is that it's probably going over the top -----provided you DO have an RCD------

Same applies to the popular question of whether you need a so-called 'polarity indicator'. (It tells you the line (live) wire is connected to the correct side).

The real problem is educating people in general to fit an RCD at all, especially in their houses, and getting them to understand how it works. ("It keeps tripping out, but everything works fine, so must be the new thing").

Vic
 

Coppershield

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This might be of interest to You

Hi David,
WWW. yandina.com/hints.htm may have the information You are after
click on the " capacitor for galvanic isolator"
they used to have complete , electrical diagrams for galvanic isolator's.
But this time I could not find it.
Good luck :).
Muzaffer

PS I have no connection with this site
 
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Anonymous

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Re: I\'d imagine that......

Thanks, that seems likely. I have had this back from JG Technology.....

1.4v negligable loss units in die cast box with screw terminals up to 6mm
2 cable. 140mm x 60mm x 30mm.

At his price, it isn't really worth my while ordering the parts from RS.
 
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Anonymous

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Re: This might be of interest to You

Hi Muzaffer,

Thanks, excellent site...though I can't see it there either. Plenty of other good tips (other than the DIY dive compressor which looks a trifle strange /forums/images/graemlins/shocked.gif)

David
 
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