Type D RCBOs

[johnnycash126]

Dear all,

I have to protect a 13 amp ring main which is currently protected by a type b rcbo.The circuit is going to be used by step down transformers from the US.Notorious for tripping on start up.I thought a change to a type D rcbo would cure this,however neither MEM or Crabtree make a type D RCBO.This makes me think that perhaps im not allowed to do this.

Anyone any experience of this?

 

[iamelectric]

i have only ever used 3 phase type D mcbs

 

[MDJ]

Do you have to have an RCBO, I would avoid one of those at all costs and try to design the circuit so it does not require one, they are fine in their own right but for a Transformer? hmm how about no chance unless the earthing requirement or enviroment means one has to be used.

 

[Pete999]

Will changing the type of rcbo from a b to a d inter fear with the disconnection times? I would have thought that the best bet would be to feed these transformers from a dedicated circuit specifically designed for this type of use, sounds like someone wants you to do a cheap fix which probably isn't safe

 

[johnnycash126]

Can I then replace the type B rcbos with type d MCBs?

 

[Pete999]

Whats the reason for that it?

 

[MDJ]

Dear all,

I have to protect a 13 amp ring main which is currently protected by a type b rcbo.The circuit is going to be used by step down transformers from the US.Notorious for tripping on start up.I thought a change to a type D rcbo would cure this,however neither MEM or Crabtree make a type D RCBO.This makes me think that perhaps im not allowed to do this.

Anyone any experience of this? Can I then replace the type B rcbos with type d MCBs?

you have been a member for 3 and a half years so I assume you are a competant spark yes? that said we are now going down the inexperienced route, what a silly question your last post was, think about what you said and then you will see what I mean.

 

[johnnycash126]

The americans are coming.And they bring step down transformers for their equipment.ie hairdryers,tongs etc.Historically,they will trip our type B MCBs.Now we have anew installation with type B rcbos. Again,I expect the breakers to trip under starting current.

 

[johnnycash126]

you have been a member for 4 and a half years so I assume you are a competant spark yes? that said we are now going down the inexperienced route, what a silly question your last post was, think about what you said and then you will see what I mean.

Dont assume.You know what that makes.I was an electrician im now in a different role.

 

[MDJ]

Whatever, a ridiculous question, first a D rated rcbo now an MCB, ever heard of a design? anyhow good luck to you whatever you decide.

 

[Pete999]

Even so mate an rcbo provides overload and earth leakage protection so if its just inrush thats tripping your rcbo changing it to a cb of the same type (b,c,d) wont make the slightest difference

 

[R G]

To put this on a circuit that your suggesting is not good , best on its own circuit especially if its tripping out an rcd . Design it and you won't need the RCBO,,

 

[johnnycash126]

Ok I understand that,but could i then change the rcbo to an MCB type d and then provide earth leakage protection by fitting RCD sockets?

 

[MDJ]

DIY alert team

 

[R G]

Ok I understand that,but could i then change the rcbo to an MCB type d and then provide earth leakage protection by fitting RCD sockets?

Are you serious , or a windup ,

 

[Pete999]

Still doesn't deter from circuit design changing from b to d will probably (dont have my BGB with me) make the disconnection time invalid

 

[johnnycash126]

Ah the gorilla again.Are you parents aware your a keyboard terrorist? You remind me of a poem.

What kind of creature bore you
Was it some kind of bat
No-one has a good word for you
But i have
****.

 

[Darkwood]

Ok I understand that,but could i then change the rcbo to an MCB type d and then provide earth leakage protection by fitting RCD sockets?

Your asking a question that makes you look incompetent to do the job... how can we know this?

You know the circuit layout existing, you need to know the Zs to even contemplate doing this.
Does the circuit require RCD cover as it is if so then no you can't swap it for an mcb.

This really should be on its own circuit protected with HRC fusing or similar if Zs is limited or if installation methods permit an mcb that suits the size of the Tx.

You haven't given us any info at all from Tx size to existing install methods yet ask questions that require this knowledge ... this implies you don't understand what you are doing ... i would be inclined to have your installation looked over by a competent Electrician - you can't just upgrade / swap circuit protective devices willy nilly you have to calculate everything again to ensure it complies to BS7671

 

[MDJ]

Ah the gorilla again.Are you parents aware your a keyboard terrorist? You remind me of a poem.

What kind of creature bore you
Was it some kind of bat
No-one has a good word for you
But i have
****.

Your questions has now got just plain daft, your replies even dafter, you are bringing it on yourself, whats the difference between a RCD and a MCB mr "I used to be an electrician"

- - - Updated - - -

Your asking a question that makes you look incompetent to do the job... how can we know this?

You know the circuit layout existing, you need to know the Zs to even contemplate doing this.
Does the circuit require RCD cover as it is if so then no you can't swap it for an mcb.

This really should be on its own circuit protected with HRC fusing or similar if Zs is limited or if installation methods permit an mcb that suits the size of the Tx.

Thank God the voice of competance, hopefully he will listen to you fella.

 

[mrloy99]

To put this on a circuit that your suggesting is not good , best on its own circuit especially if its tripping out an rcd . Design it and you won't need the RCBO,,

such a load of tosh, Ray.I don't know why you are so hard on the guy,he's only asking for advise.design design design.I recon the guy is refering to a 32amp circuit when he talks about 13amp ring main. Its not the rcd bit thats tripping on his rcbo...the type D is to allow for the increased inrush current.Am I missing something here??Whats wrong with using a stand alone rcd at the origin as opposed to rcbo.And type Ds are available in other makes. Yes if using an mcb the design Zs is probably(cant be arsed getting bgb out)around .30 but with the inclusion of the rcd surely that becomes the overiding device when acceptable tripping time is the concern.But having said all that you will probably find that a type c rcbo will cure your problem.I would be more concerned with the different design frequency of your american equipment