Discuss Sub Board fed from a plug top, EICR Coding in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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I recently undertook an EICR report for a small house and the conservatory extension had a separate fuseboard which was fed from a 13A plug top.

Obviously this is not ideal but when coming to code it I couldn’t describe why it is any more than a C3.

The main distribution board feeding the socket that the sub-board plugs into is RCD protected. Surely any fault that could occur from circuits after the sub-board are then RCD protected, any overloading etc of the plug top is protected by the both the MCB at the main board and the 13A fuse in the plug.

Can anyone more experienced point me to what (of anything) I would be doing classifying it as a C3?
 
can't see any danger (except prerhaps trip hazard) so agree with C3. may be a comment that the sub has temp. plug-in feed .
 
Thank you all for your inputs so far.

Is there anyone who disagrees with a C3?

The sub-board had 4 circuits:- 2 x Radial socket (each supplying one socket) 1 x Lighting (supplying 2 wall lights) and 1 x 20A air conditioning unit.
 
overload on the 13A plug fuse? check that it's not a nail.
 
Thank you all for your inputs so far.

Is there anyone who disagrees with a C3?

The sub-board had 4 circuits:- 2 x Radial socket (each supplying one socket) 1 x Lighting (supplying 2 wall lights) and 1 x 20A air conditioning unit.
Just the 20A rated air conditioning would possibly incur the C2 potential for overload. What is the load of the air conditioning unit.
13 A plug top with its bottom feeding a higher rated isolator is fine if loading is less than the lowest so C3 but.... It’s screaming in my sub conciseness for a C2.

loved the code S for silly Wilco.
come across these Types of issues all the time.
I think, Why do that, but When you really look and examine the situation it’s not dangerous, just silly.
 
I would treat it like any other DB
List the supply characteristics, incoming fuse type and rating etc.

It is in many ways similar to a caravan or temporary building.
Fixed wiring and distribution, fed from a socket that is part of a larger installation
 
Just the 20A rated air conditioning would possibly incur the C2 potential for overload. What is the load of the air conditioning unit.
13 A plug top with its bottom feeding a higher rated isolator is fine if loading is less than the lowest so C3 but.... It’s screaming in my sub conciseness for a C2.

loved the code S for silly Wilco.
come across these Types of issues all the time.
I think, Why do that, but When you really look and examine the situation it’s not dangerous, just silly.
Something doesn’t seem right with me classing it as only a C3 either!

The loading of the air conditioning unit shouldn’t matter should it? If it pulls more than 13A the plug top would blow.

My concern is the 1.5mm flex cable that is on the plug top could overheat if too much current is drawn .. but the fuse would operate if there was any danger? Or am I wrong in assuming the 1363 fuse is adequate?
 
also depends on the 1.5mm flex. the 1363 fuse will carry a fair overcurrent for a while, causing the flex to overheat. giong by the 20A A/C load, i might lean towards a C2. what if the flex happened to be on the floor and a rug placed over it?
 
Are you going to check every plug at the site and assess its potential for danger. The fact it has a consumer unit connected from it isn't really relevant.
 
In theory the 13A fuse is adequate protection for the plug and 1.5mm cable (not thermally insulated), and so what is down-stream is not a concern load-wise (just as you would have for an 8-way distribution strip, etc).

In practice we all know that most 13A plugs don't last long if run at or above the 13A fuse rating and will end up showing signs of thermal stress, possible also damaging the socket outlet they are plugged in to.

Still it would seem to be reasonable to at least mention it in the report. Coding it as something such as C3 is not too far from the BPG#4 guidance:
  • Socket-outlet mounted in such a position as to result in potential damage to socket, plug and/or flex.
 
Quite often the small AC units for conservatories are designed to be 'plugged in' ie less than 13A.
Is it just on a 20A mcb on the cons unit but may actually draw much less current?
From info you've provided C3 for me.

BTW .... plug top fuse is 1362
 
also depends on the 1.5mm flex. the 1363 fuse will carry a fair overcurrent for a while, causing the flex to overheat. giong by the 20A A/C load, i might lean towards a C2. what if the flex happened to be on the floor and a rug placed over it?
The flex cable won’t be covered, it’s in a kitchen cupboard drilled directly through the wall and into the sub-board - roughly 60cm length of cable.

The socket it’s plugged into is on a 4mm cable radial backed up by a 16A MCB at the main board.

I want to C2 it but am finding it hard to pinpoint why according to BS7671.

Moving forward, would it be acceptable to extend the existing 4mm cable to feed the new board? Or should a sub main have a dedicated supply?
 
In theory the 13A fuse is adequate protection for the plug and 1.5mm cable (not thermally insulated), and so what is down-stream is not a concern load-wise (just as you would have for an 8-way distribution strip, etc).

In practice we all know that most 13A plugs don't last long if run at or above the 13A fuse rating and will end up showing signs of thermal stress, possible also damaging the socket outlet they are plugged in to.

Still it would seem to be reasonable to at least mention it in the report. Coding it as something such as C3 is not too far from the BPG#4 guidance:
  • Socket-outlet mounted in such a position as to result in potential damage to socket, plug and/or flex.
That Guide reference is citing a socket outlet location whereby its position is likely to result in damage to the socket, for example if it is too close to the floor. It does not apply to this situation.
 
The flex cable won’t be covered, it’s in a kitchen cupboard drilled directly through the wall and into the sub-board - roughly 60cm length of cable.

The socket it’s plugged into is on a 4mm cable radial backed up by a 16A MCB at the main board.

I want to C2 it but am finding it hard to pinpoint why according to BS7671.

Moving forward, would it be acceptable to extend the existing 4mm cable to feed the new board? Or should a sub main have a dedicated supply?
Why are you Coding it at all.
 
That Guide reference is citing a socket outlet location whereby its position is likely to result in damage to the socket, for example if it is too close to the floor. It does not apply to this situation.
I known, what it is saying is if on inspection you see the socket is likely to be physically damaged, report it.

To me if you see it might be thermally damaged by its use, it is much the same. After all, if you see an already thermally damaged socket it would be a C2 as needs replacing.
 
I known, what it is saying is if on inspection you see the socket is likely to be physically damaged, report it.

To me if you see it might be thermally damaged by its use, it is much the same. After all, if you see an already thermally damaged socket it would be a C2 as needs replacing.
If that is how the Guide quotes it then it is referring to position nothing else.
 

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