Suitability of circuit accessories.

[Julie.]

I didn't design the cct Julie so none of that is down to me or part of the issue. Any number of faults could occur in an air con unit, its not just a motor.

Agree, but if you are doing an EICR then you need to go over the design in terms of checking compatibility of the protective devices to the cable size, Zs etc.

Of course there could be many faults within the air-con unit, but unless you have the full diagram etc, you can't assess it. Are you doing an EICR on the electrical system or the inner workings of all electrical and electronic equipment on-site?

Air con units are designed with various protections internally for each area, electronics, motor, etc. you would really have to have all the details of the design in order to assess this!

 

[snowhead]

Have you never seen a circuit accessory that's overheated &/or melted over a period of time? I know I have.

Since the advent of plastic, self extinguishing, isolators / accessories, Yes, many times.
Moreso on circuits with a protective device that matches the Isolator rating, or even less, than those where it didn't.

You've reported your concerns, they've been dismissed, that's it as far as you're concerned.

 

[Leezo]

Agree, but if you are doing an EICR then you need to go over the design in terms of checking compatibility of the protective devices to the cable size, Zs etc.

Of course there could be many faults within the air-con unit, but unless you have the full diagram etc, you can't assess it. Are you doing an EICR on the electrical system or the inner workings of all electrical and electronic equipment on-site?

Air con units are designed with various protections internally for each area, electronics, motor, etc. you would really have to have all the details of the design in order to assess this!

Yes of course I'm assessing the compatibility of protection & wiring, there's no issue there, there is this issue of compatibility between cct protection & the rating of accessories. I agree there is built in protection with appliances like these but I'm a sparky & I'm not really concerned with that, just the suitability of the system taking into account a multitude of eventualities.

What I guess I'm really looking for is for someone to tell me where in the regs it says that a fixed load of a certain size negates the designers responsibility to select suitably rated accessories for the design current, then I'll wind my neck in if I'm wrong. I have to say though I don't agree with this statement made in the first reply to my post that in the case of fixed equipment the design current is that of the load of the appliance as any Tom, Dick or Harry can work on the load side of an isolator & change the A/C unit for one with a higher current rating.
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Since the advent of plastic, self extinguishing, isolators / accessories, Yes, many times.
Moreso on circuits with a protective device that matches the Isolator rating, or even less, than those where it didn't.

You've reported your concerns, they've been dismissed, that's it as far as you're concerned.

JOKER... quote where in the regs it backs up your 'opinion' before you try telling me that. I didn't come on here to "report my concerns" I came on here for the advice of people who know what they're talking about so enough from you.
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Accessories are designed to take into account short duration fault conditions with no adverse effects.

Yes, over & above that of the rating of the accessory which in this case is 20A, the problem is, the protective device is 32A so how long should I expect my isolator to cope with something close to 40A before it melts.

 

[Julie.]

Yes of course I'm assessing the compatibility of protection & wiring, there's no issue there, there is this issue of compatibility between cct protection & the rating of accessories. I agree there is built in protection with appliances like these but I'm a sparky & I'm not really concerned with that, just the suitability of the system taking into account a multitude of eventualities.

What I guess I'm really looking for is for someone to tell me where in the regs it says that a fixed load of a certain size negates the designers responsibility to select suitably rated accessories for the design current, then I'll wind my neck in if I'm wrong. I have to say though I don't agree with this statement made in the first reply to my post that in the case of fixed equipment the design current is that of the load of the appliance as any Tom, Dick or Harry can work on the load side of an isolator & change the A/C unit for one with a higher current rating.
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JOKER... quote where in the regs it backs up your 'opinion' before you try telling me that. I didn't come on here to "report my concerns" I came on here for the advice of people who know what they're talking about so enough from you.

well 432.3 is the obvious one!

I think snowhead's comment is that you reported your concern to your supervisor, he has dismissed it therefore that's it.

 

[Leezo]

well 432.3 is the obvious one!

That's about protective devices, it certainly doesn't refer to selection of under rated accessories?

 

[Julie.]

That's about protective devices, it certainly doesn't refer to selection of under rated accessories?

I think you need to take a break and cool off.

Just relax and re-read what you have said and the responses, then think about it, it appears like you are reacting rather than analysing.

 

[Leezo]

Since the advent of plastic, self extinguishing, isolators / accessories, Yes, many times.
Moreso on circuits with a protective device that matches the Isolator rating, or even less, than those where it didn't.

You've reported your concerns, they've been dismissed, that's it as far as you're concerned.

Having re-read your post I understand what you're saying about reporting my concerns & I apologize unequivocally for my somewhat surly reaction.

 

[Julie.]

That's funny, I just haven't seen anyone post anything that makes sense, you were doing ok though Julie until you quoted a completely irrelevant regulation.

Ok, let's try this

You have a cable capable of 20A on a 10A load

If I fit a 40A MCB, is the cable undersized, or is the MCB over sized?

If you say it's the MCB that's too large then 432.3 would be appropiate

The standards always work from one direction only.

They don't put the point in both directions

There isn't "1.2.3.4 :equipment must be suitable for the Voltage of the system" followed by the opposite viewpoint "1.2.3.5 : A Voltage unsuitable for the equipment must not be used"

It is necessary only to confirm one point of view.

 

[Leezo]

Ok, let's try this

You have a cable capable of 20A on a 10A load

If I fit a 40A MCB, is the cable undersized, or is the MCB over sized?

If you say it's the MCB that's too large then 432.3 would be appropiate

The standards always work from one direction only.

They don't put the point in both directions

There isn't "1.2.3.4 :equipment must be suitable for the Voltage of the system" followed by the opposite viewpoint "1.2.3.5 : A Voltage unsuitable for the equipment must not be used"

It is necessary only to confirm one point of view.

You've lost me...

 

[Julie.]

You've lost me...

Your thought, that the isolator is undersized @ 20A, is based on the fact that the protection is 32A

This is EXACTLY the same as saying the protection @32A is oversized as the isolator is only 20A

The regs only need to cover one point of view as the other is automatically covered!