Rank: Forum user 
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Hi everyone,
I recently attended an electrical safe working seminar and one of the speakers said about extension leads should not be daisy chained and when using a extension reel which is coiled the maximum wattage of the equipment should not exceed 700 Watts.
Can anyone point me in the right direction to where this is stated i.e. BSI. IEE etc. as I have put it in my risk assessment that this should not happen but the engineering manager wants proof that this is correct.
I have taken him through the risk assessment and why I have included it, but I am being accused as being over zealous, and is refusing to adhere to the risk assessment.
I have brought the issue up in the morning management meeting but the MD agrees with him.
Thanks in advance
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Rank: Super forum user 
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Daisy chaining ext leads can increase the earth fault loop impedance above that to ensure adequate ADS.
Coiled extension leads will generate sufficient heat to melt, due to the Joule heating of the cable as well as the lack of ventilation and other physical issues.
Most new extension leads have a coiled & uncoiled rating from the manufacturer.
BS7671 states in reg. 510.3 that manufacturers instructions shall be taken account of.
It is noted that extension leads do not come under 767,1, however, I'm would guess that ignoring makers guidance would fall foul of MHSWR PUWER98 etc. etc.
BTW, I've deliberately used technical terms, as an Engineering Manager should not be asking such things he should KNOW if he is competent to hold his position.
If you want further simplification come back to us, I'm sure Zimmy will be along shortly as well as a few others who can back this up.
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Rank: Super forum user
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Shame I can't correct my typo though, 7671!
Not, 767,1!!! ;)
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Rank: Forum user
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David
I recently carried out a safety inspection in our engineers workshop and found a badly maintained, fully coiled(30m) extension reel. The flex was badly damaged, it had a 2300w heat gun plugged in to it and it was on at the wall(not in use)
To cut a long story short, looking at the real which I condemned it stated the max wattage in the fully coiled and un coiled state. It was around 700w.
A lot of these newer reels will have information stickers stating this.
Not exactly what you were asking, but hope it helps.
MAT
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Rank: Super forum user
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No more to say on this one. Paul is quite correct.
Re daisy chains, on more than one occasion I have seen (and no doubt that Paul has seen the same) home-made extension leads without earth (cpc) cores. These were to have been used for the mower etc (two core cable to the mower) These extension leads were then coupled with 3-core extension leads. No need to go any further with this.
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Rank: Forum user
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I can't type either 'Reel'
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Rank: Super forum user
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You're ok Mat, no one awake yet mate :-)
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Rank: Forum user
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Zimmy you're quite correct.
I'm glad you are all so understanding on here : -)
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Rank: Super forum user 
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Cable reel in use with cable still around the drum - indiction coil effect. Cause of fire.
Daisy chaining extensions leads to a longer time for a RCD to trip when necessary to do so if the fault is at the end away from the connection to power.
I am not an electrician but do understand that much.
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Rank: Super forum user
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Sorry fire but a long extension lead does NOT lead to rcd's taking longer to trip. A long extension lead, as in a long cable length, means that a higher Zs is recorded (ohms) and thus smaller earth fault current, this then means that MCB'S/FUSES take longer to open circuit.
Current flow is relatively slow but the effect is almost instantaneous. A bit like putting ball bearings in a glass tube. If the tube is full, as you add one in one end one falls from the other end.
Rob
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