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stevesown

Swapping an MCB

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stevesown

Hi all,

I have a customer with a metal box type Wylex consumer unit, which presently has a NHXSBSB16 breaker feeding a small pump set which is just fed Direct Online.

I need to swap to a Type C breaker as the new pump set is powered by variable speed drives.

The question I need answering is:- Can I put just a normal type C breaker in the consumer unit?  as the RCBO types normally trip when you connect variable speed drives due to the characteristics within the drives.

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ProDave

Why do you think you need a type C for a VSD?  They almost always have soft start.  If anything it would be the DOL pump that would need the type C

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Rob.
4 minutes ago, ProDave said:

Why do you think you need a type C for a VSD?  They almost always have soft start.  If anything it would be the DOL pump that would need the type C

 

VSDs need to charge their DC bus capacitors and as such have a large inrush current when the VSD is first powered up. 

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stevesown

Hi Dave thanks for the reply, In my years of experience, I always tend to have problems with Type B on all installations weather VSD or DOL, so I normally change them as a matter of course.

My main question is, is it OK to remove the RCBO & change it for a normal MCB on the Wylex metal box consumer unit?

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Andy™

may... maybe not. if the circuit doesnt need RCD protection and your cables sizes / zs are OK for a type C then yes. otherwise no

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Evans Electric

Isn't there some bumph about  creating a " Risk assessment"  to  avoid the use of an RCD  ?  

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binky
1 hour ago, Evans Electric said:

Isn't there some bumph about  creating a " Risk assessment"  to  avoid the use of an RCD  ?  

 

Yes, you can omit things provided you can justify your actions, and to do that your need a Risk Assessment. For Example.,I much prefer not to RCD my solar circuits for various reasons to do with reliability - RCDs dont like the way inverters start up and shut down, not usually an issue, but with some makes a total pita! I can justify this on the grounds my cable runs are usually surface / buried more than 50mm, and I don't fit sockets under the panels :D

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Evans Electric

What does one actually  do with the Risk Assessment ?     Send copies to your MP ,  the NICeic ,  Building Control , The Queen  ?  

 

I've only ever done any twice ,  to  Project Managers .   

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ProDave
1 hour ago, Evans Electric said:

What does one actually  do with the Risk Assessment ?     Send copies to your MP ,  the NICeic ,  Building Control , The Queen  ?  

 

I've only ever done any twice ,  to  Project Managers .   

File it so you can present it in court IF the smelly stuff hits the fan.

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Murdoch
2 hours ago, Evans Electric said:

What does one actually  do with the Risk Assessment ?    

 

I've never done one ....... so I suppose the logical answer is send a copy with the certificate and file a copy so your CPS can view it.

 

 

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Evans Electric

How do they know you only just wrote it down ?    

 

NIC Man      "Oh my goodness you havn't fitted an RCD to this circuit " 

Me                  " Ah  but I wrote it on this piece of paper " 

NIC Man       " Thats OK then  " 

 

 

The last ones I did were for a Project management  team . 

Q .  Will your operatives be working at  height  .

A.   Yes from a mobile scaffold tower .

Q.  What precautions will you take to prevent a fall?

A    We will be very careful .   

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Evans Electric
2 minutes ago, Murdoch said:

 

I've never done one ....... so I suppose the logical answer is send a copy with the certificate and file a copy so your CPS can view it.

 

 

I honestly don't think they'd welcome it Murdo  . 

 

I've said this before but I keep wondering if all the local building control departments now all have a database  of all the electric jobs carried out  since  Part Pee  came in .   And would they be willing to search it for , say , a house buyer  who wants to know when it was rewired & by whom. 

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Blue Duck
13 minutes ago, Evans Electric said:

How do they know you only just wrote it down ?    

 

NIC Man      "Oh my goodness you havn't fitted an RCD to this circuit " 

Me                  " Ah  but I wrote it on this piece of paper " 

NIC Man       " Thats OK then  " 

 

 

The last ones I did were for a Project management  team . 

Q .  Will your operatives be working at  height  .

A.   Yes from a mobile scaffold tower .

Q.  What precautions will you take to prevent a fall?

A    We will be very careful .   

 

 

Working off a scissor lift in a  supermarket warehouse, site manager asks us what is our escape plan?

I told him we would jump off onto that pallet of toilet roll.

 

Not amused

....

 

 

:lol:

Edited by Blue Duck

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Evans Electric

Imagine a laughing  smiley face . 

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Murdoch
39 minutes ago, Evans Electric said:

I honestly don't think they'd welcome it Murdo  . 

 

 

I find they struggle to ask sensible questions ......... so insisting on seeing such documents is surely something they want to see.

 

Last Stroma inspection they wanted to see my "complaints procedure" - a written copy - I said I don't get complaints - I don't think the assessor thought my response was suitable!

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kerching

Risk assessment?

try doing one for a diving course with a projected depth of 75m!

 

risk......death

cause....running out of gas and/or drowning

method of risk reduction.....stay in Pub

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Bruspark
1 hour ago, Murdoch said:

 

Last Stroma inspection they wanted to see my "complaints procedure" 

Is he back at work yet ? 

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binky
45 minutes ago, kerching said:

Risk assessment?

try doing one for a diving course with a projected depth of 75m!

 

risk......death

cause....running out of gas and/or drowning

method of risk reduction.....stay in Pub

Probably goes down as well as "I'm 54 and still alive with every intention of reaching retirement"  :^O 

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Sharpend

I think we all have to do a mental risk assessment everyday in this day and age,

 

if I make it too work and back without getting mugged, stabbed or shot at then I consider myself to have passed and the risk assessment was successful. 
 

:coat 

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NozSpark
4 hours ago, Evans Electric said:

I honestly don't think they'd welcome it Murdo  . 

 

I've said this before but I keep wondering if all the local building control departments now all have a database  of all the electric jobs carried out  since  Part Pee  came in .   And would they be willing to search it for , say , a house buyer  who wants to know when it was rewired & by whom. 

 

I know that the NIC do (well, the notified ones....... )

http://www.checkmynotification.com

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Sidewinder

Just remember if you are doing RA’s as part of your design, make sure that your insurance covers that aspect of your work.

A lot of “normal” electrical contractor policies won’t.

For industrial or commercial work, this RA it down to the “Duty Holder” for the premise under EAWR.

If, you as a contractor do the RA, then you provide that as a consultant, & you need to be sure that you are covered, otherwise if things go wrong, it’s you that will be sought out.

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binky

would that be covered by Indemnity Insurance?

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Sidewinder
59 minutes ago, binky said:

would that be covered by Indemnity Insurance?

Only if you have specifically included it by telling them that you are going to be doing it, and you have provided evidence of competence, or not to allow them to evaluate the premium as to whether you are competent to give that advice or not.

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Murdoch
3 hours ago, Sidewinder said:

Just remember if you are doing RA’s as part of your design, make sure that your insurance covers that aspect of your work.

A lot of “normal” electrical contractor policies won’t.

For industrial or commercial work, this RA it down to the “Duty Holder” for the premise under EAWR.

If, you as a contractor do the RA, then you provide that as a consultant, & you need to be sure that you are covered, otherwise if things go wrong, it’s you that will be sought out.

 

"informative"

 

Yet some BS references suggest we should be doing them ................. and I doubt many people realise the impacts of doing them and getting them wrong!

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Sidewinder

If you look at BS7671, you will also see “normative” & “informative” appendices,

Normative appendices have as much relevance as the main part of the standard.

That is another thing that many miss!

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