Use TP breaker as two pole?

[CAWORK]

Evening All

My cousin has a caravan (quite a lot of years old) with a plain plastic enclosure (no manufacturing marking) containing an RCD main switch and two DP MCBs, 10A and 6A. Inside the enclosure there is no bus bar, RCD and MCBs being linked via flexible cords (as is normally the case in caravans).

Situation:

The 6A MCB has become damaged and needs to be replaced.

Went to one wholesaler a few weeks back (with damaged MCB) said it was nothing they had on the shelf, gave my phone no. and email, heard nothing.

Went to another wholesaler today, nothing they had on shelf, but could order two pole breaker- quoted £37 without VAT!!!!!!!

I have seen TP breakers fairly cheap at Screwfix, and was wondering if it would be acceptable to use one as a DP circuit breaker, leaving the third pole unused?

If this is acceptable, there is plenty of removable blank plates on the front of the enclosure cover to allow for the extra space.

I know this may not sound ideal, and am not too keen on the idea myself, but the price quoted earlier on was quite shocking.

Kind Regards

 

[333rocky333]

Neutral current always flows the opposite way to the line current, which is not the same as a 3 pole breaker so I would say pay for the right thing and do it properly.

 

[JohnD]

You say that what you need is a 6A DP MCB.

Show us a photo of the old one, and its consumer unit.

Perhaps it is an antique, and you are being quoted for a museum piece.

 

[CAWORK]

Neutral current always flows the opposite way to the line current, which is not the same as a 3 pole breaker so I would say pay for the right thing and do it properly.

Many Thanks.

I was just a bit astonished at the quoted price, but prepared to pay the price if necessary to do it properly. Regarding the opposite Neutral current flow (which I am fully aware of) are genuine DP breakers marked for polarity? I don't think I can actually recall previously coming across any.

You say that what you need is a 6A DP MCB.

Show us a photo of the old one, and its consumer unit.

Perhaps it is an antique, and you are being quoted for a museum piece.

HI JohnD,

Yes I require a 6A DP MCB.

I would certainly be happy to post a photo, however my phone is very old (yes intend to replace it soon) with poor picture quality.

Further details:

German Caravan, originally had German sockets (replaced some years back with DP switched BS1613 sockets), wiring 1.5 PVC Flex.

"Consumer Unit" enclosure : plastic enclosure, no manufacturer marking.
MCBs Manufactured by "WEBER"

Took MCB to the first wholesaler a few weeks back (heard nothing)

Took MCB to a different wholesaler earlier today, explained it was for caravan, said he could order a Wylex one, but for the price I mentioned earlier on. (It was mentioned DP MCBs are something very rarely requested).

Kind Regards

 

[JohnD]

you do occasionally see DP RCBOs, probably cost at least as much. But the problem may be obtaining one to fit the CU, especially if it is an old-model, foreign one. If you were quoted £37 +VAT it's still cheaper than changing over to a new, modern, UK installation.

But that could be worth considering if there are signs that additional replacements may be needed.

Maybe if you start a thread with "Caravan DP Breaker" there may be people with experience in that field. I can't remember what boats use when they have a shore supply, the rules are special.

Or you could try calling on the "Electric Ex UK" section as they might be ten a penny in some other country. Until end of March, imports, taxes, orders and payments with EU countries are easy.

...

 

[Robin0577]

DP RCBOs aren't that hard to come by, or that expensive, but the question is will one fit?
https://www.rapidonline.com/Europa-...MIrbeb5pre3wIVLrHtCh2XwgD9EAQYAiABEgKQ9fD_BwE

 

[SUNRAY]

Many Thanks.

I was just a bit astonished at the quoted price, but prepared to pay the price if necessary to do it properly. Regarding the opposite Neutral current flow (which I am fully aware of) are genuine DP breakers marked for polarity? I don't think I can actually recall previously coming across any.



HI JohnD,

Yes I require a 6A DP MCB.

I would certainly be happy to post a photo, however my phone is very old (yes intend to replace it soon) with poor picture quality.

Further details:

German Caravan, originally had German sockets (replaced some years back with DP switched BS1613 sockets), wiring 1.5 PVC Flex.

"Consumer Unit" enclosure : plastic enclosure, no manufacturer marking.
MCBs Manufactured by "WEBER"

Took MCB to the first wholesaler a few weeks back (heard nothing)

Took MCB to a different wholesaler earlier today, explained it was for caravan, said he could order a Wylex one, but for the price I mentioned earlier on. (It was mentioned DP MCBs are something very rarely requested).

Kind Regards

As this is all wired in flexible wire rather than busbar, any make will do the job assuming the existing isn't an oddball size and shape and the replacement will fit in the space.
If the 3pole will fit, there is electrically no reason it shouldn't work as they are basically single pole breakers fixed together and any one of them is able to trip the whole stack. Don't worry about the 'neutral being in the opposite direction' red herring.

DO NOT BE TEMPTED TO CONVERT A 3POLE TO 2POLE by removing one breaker as there is a very high chance of damaging it.

 

[Risteard]

DP RCBOs aren't that hard to come by, or that expensive, but the question is will one fit?
https://www.rapidonline.com/Europa-...MIrbeb5pre3wIVLrHtCh2XwgD9EAQYAiABEgKQ9fD_BwE

I get Hager RCBOs with a switched neutral for the same price as single pole Hager RCBOs. Any work done in the south of Ireland always uses the switched neutral variety - a single pole RCBO simply isn't the done thing there. So really they're not at all difficult to get.

It must be remembered that you must not mix manufacturers' equipment unless you want to bear the responsibilities of the manufacturer of the assembly, however.

 

[333rocky333]

are genuine DP breakers marked for polarity? I don't think I can actually recall previously coming across any.

There usually marked 1 2 3 4, maybe it don't matter I don't know, but as you say its a Generic enclosure and no bus bar, maybe a cheaper makes available.
Theres also the option depending what you have now of removing both the Mcb and the Rcd and fitting a DP Rcbo.
A photo would help regardless of the quality.

 

[flameport]

Regarding the opposite Neutral current flow (which I am fully aware of) are genuine DP breakers marked for polarity? I don't think I can actually recall previously coming across any.

They are not, and couldn't be - MCBs only contain passive components (a wire coil and bimetallic strip usually), so which is the load and supply doesn't matter.
Neither is there any concept of polarity or current flow - these are AC devices and the current direction changes continually.
A 3 pole MCB will work, there is no difference to a 2 pole other than the additional pole, and the 3 poles are all electrically separate identical items anyway.

2 pole items are uncommon in the UK hence the high prices. They are more common in Europe and probably a lot cheaper there - but for a single device it's probably not worthwhile sourcing from far away as there will be significant delivery costs involved.

Note that RCBOs, RCDs and other devices such as AFDDs often do need to be connected in a certain way, as they may not operate correctly if connected in ways the manufacturer did not intend.

 

[SUNRAY]

As this is all wired in flexible wire rather than busbar, any make will do the job assuming the existing isn't an oddball size and shape and the replacement will fit in the space.
If the 3pole will fit, there is electrically no reason it shouldn't work as they are basically single pole breakers fixed together and any one of them is able to trip the whole stack. Don't worry about the 'neutral being in the opposite direction' red herring.

DO NOT BE TEMPTED TO CONVERT A 3POLE TO 2POLE by removing one breaker as there is a very high chance of damaging it.

Suggestion:

https://cpc.farnell.com/abb/s202-b6/circuit-breaker-thermal-mag-2/dp/MC02426?st=2 pole mcb

https://www.ebay.co.uk/itm/Crabtree...hash=item3d2f2ef8ab:m:mcwtnheS9_W8g5mffi8v0Sg

If it's just for a couple of lights then: https://www.ebay.co.uk/itm/MERLIN-G...=item4b53bef514:g:qOMAAOSwxG9b2e0B:rk:47:pf:0